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N a .
Proceedings of the April 1990
Researchers Meeting
10 Years of Collaborative Research
on Beans and Cowpeas
E U
Bean/Cowpea Collaborative
Research Support Program
Michigan State University
PROCEEDINGS
OF THE INTERNATIONAL RESEARCH MEETING
OF THE
BEAN/COWPEA COLLABORATIVE RESEARCH SUPPORT PROGRAM
April 30 May 3, 1990
200 Center for International Programs
Michigan State University
East Lansing, Michigan
Grant No. DAN-1310-G-SS-6008-00
Agency for International Development
Washington, DC
Cover photo by Bonnie Ze11
TABLE OF CONTENTS
LETTER FROM THE DIRECTOR
INTRODUCTION AND OVERVIEW . .
ROSTER OF BEAN/COWPEA CRSP PROJECTS
BEAN/COWPEA CRSP PROJECT REPORTS
Brazil/BTI/Roberts . .
Cameroon/Purdue/Murdock . .
Dominican Republic/UNL/Coyne
Dominican Republic/UWI/Maxwell
Ecuador/UMN/Graham . .
Guatemala/Cornell/Wallace .
Honduras/UPR/Beaver . .
INCAP/WSU/Swanson . . .
Malawi/MSU/Isleib (Adams)
Mexico/MSU/Harpstead . .
Nigeria/UGA/McWatters . .
Senegal/UCR/Hall . . .
Tanzania/WSU/Silbernagel
CRSP PRESENTATIONS . . .
NON-CRSP ABSTRACTS ......
SMALL GROUP DISCUSSIONS . .
MINI-PANEL REPORTS . . .
SUMMARY . . . . .
AGENDA .
APPENDIX A William R. Furtick .
APPENDIX B CRSP Buy-Ins . .
. 1
. 5
. 7
. 11
. 16
. 21
. 25
. 28
. 33
. 36
. 39
. 43
. 46
. 50
. 56
. 61
. 91
. 103
. 113
. 125
. 127
. A-131
. B-137
APPENDIX C Roster of Participants . . .
APPENDIX D Bean/Cowpea CRSP Global Plan . .
APPENDIX E Bean/Cowpea CRSP Management Groups
C-141
. D-145
. E-155
MICHIGAN STATE UNIVERSITY
BEAN/COWPEA CRSP MANAGEMENT OFFICE EAST LANSING MICHIGAN 48824-1035
200 CENTER POR INTERNATIONAL PROGRAMS TELEX: 263359 CRSP UR
VOICE (517) 355-4693 FAX: (517) 336-1073
October 1, 1990
TO: Researchers and Friends of the h aea/Cowpea CRSP
FROM: Pat Barnes-McConnell, Direct 7
The community of scientists, administrators and producers who have worked
together over the last ten years are seeing unfolded before them the
successful results of their work. Working together season after season, year
after year, the dedication and commitment are paying off with answers to some
of the most troublesome problems facing bean and cowpea production in the
developing world.
What are the factors that have contributed to the accomplishments of this
exciting program?
1. Engagement of the leading scientists and research facilities at
established bean and cowpea research centers of excellence in U.S.
2. Collegial partnerships established among these U.S. teams and the leading
bean and cowpea scientists in identified Host Countries (HCs).
3. Equal sharing of the A.I.D. financial support between the U.S. and HC
researchers.
4. Annual contributions, in dollar or in kind, from both U.S. and HC
institutions.
5. Engagement of significant U.S. and HC administrators as Institutional
Representatives to provide critical backup support and reinforcement.
6. Integration of biological and social science perspectives in the design
and implementation of project research.
7. Program-wide integration of a Women in Development perspective.
8. Long-term financial support over a timeframe required for the research
undertaken.
9. A CRSP scientific network providing timely and consistent professional
monitoring and feedback to the research teams.
10. A management office facilitating program administration, communication and
functioning.
MSUis an Affirmative Action/Equal Opportunity Institution
The value of these factors has been apparent over the life of the program. It
is emphasized by the considerable extent to which others, not currently
participating in the CRSP, are anxious to do so. Many of these scientists,
not presently involved, could add to the significant contributions of the CRSP
if a way were found to fund the integration of their efforts. In this period
of constrained financial resources, the CRSP has had to assess its research
efforts and determine the best way to make maximum use of limited resources to
support program goals.
The May 1990 Research Meeting of the Bean/Cowpea CRSP was organized to
consider these issues and to clarify the next research steps crucial for the
coming decade. The timing of the meeting was planned to coincide with the
demands of a new extension request as the current CRSP authorization period
winds down. Called upon to assist the CRSP community with this planning task
were colleagues from the International Agriculture Research Centers and
related regional programs, interested but currently non-participating U.S. and
national program scientists, representatives from the private sector and other
persons with similar world food and hunger concerns.
The Proceedings is the product of this thoughtful coming together. It is
designed to represent most of the major accomplishments presented by the teams
as well as the subsequent thinking that grew out of the deliberations. It
cannot hope, however, to convey all of the rich professional associations and
program connections that resulted from the meeting's interactions.
Nonetheless, as we proceed into the second decade of bean and cowpea research
and training partnerships, we are well served by the ideas and reflections
offered. An increased role for both new biotechnology research at the
molecular level and socio-economic/socio-cultural research is apparent.
Contributions from small-scale farmers, especially women farmers, are
increasingly encouraged and accepted. Further, as the scientists have carried
out their individual research strategies, greater value is being placed on
collaborating with colleagues in other disciplines and other programs who are
working toward the same objectives and with the same crops and farm settings.
Thus, we see not only a more productive CRSP but a program with greater
maturity, i.e., relevance, technical sophistication and programmatic
integration.
With the growing pool of bean and cowpea scientists being generated by the
CRSP worldwide, we have every expectation that the next few years will witness
further extraordinary improvements in the ability of beans and cowpeas to
contribute to family diets and income. As you read through this document, we
invite your responses and your participation in the continuing dialogues that
will help to make it happen.
INTRODUCTION AND OVERVIEW
Convened by the Bean/Cowpea Collaborative Research Support Program (CRSP) at
Michigan State University, bean and cowpea scientists from Africa, Asia, Central
and South America and the United States met in East Lansing in May, 1990. The
objectives of the meeting were to share research progress, to report relevant
research achievements and needs and to define appropriate research directions
for the future. Project reports, guest speakers, poster sessions, mini-panels
and small group discussions helped to meet these objectives and identify bean
and cowpea research needs for the 1990s.
As background for the meeting, it was acknowledged that the average annual
growth rate of the per capital gross national product in low- and middle-income
countries was a negative 2.9 percent in sub-Saharan Africa and a negative 1.2
percent in Latin America and the Caribbean. This phenomenon has serious
implications for food production and malnutrition in these regions. Beans are
an important crop in the humid tropics of Latin America and Africa while cowpeas
are important in the semi-arid areas of both continents especially sub-Saharan
Africa. Both legumes play major nutritional roles for family diets and income
generation. The Bean/Cowpea CRSP is making significant contributions to these
areas by improving production and utilization of these crops.
The Bean/Cowpea CRSP has thirteen projects which support research on plant
pathology, entomology, food science, plant breeding, social science, soil
science and physiology. Each project gave a full report of its research, which
was then followed by a discussion. Summaries of these sessions are presented in
order by country in the next section of this publication.
Brief summaries of related research by non-CRSP participants are also included.
These proceedings also contain the invited papers given on "Exploring New Bio-
technology for CRSP Research," "Socio-Economic Impact Assessment," and "Food
Science and Technology in the Total Food Delivery System." Following the
presentations, four discussion groups met and subsequently reported the outcome
of their deliberations. These groups included: (1) ethical issues in research,
(2) biotechnology in developing countries, (3) facilitating technology transfer,
and (4) designing research for sustainable agriculture. Reports of the major
outcome of these discussions are summarized. Some of the recommendations from
the group discussions include: (1) increase farmer involvement in the develop-
ment and implementation of the projects; (2) increase involvement of the private
sector in the research program; (3) expand understanding of the farmers' complex
farming systems; (4) encourage cross-CRSP collaboration; (5) utilize multi-
disciplinary teams to address the ethical issues in research; and (6) maintain
the free exchange of germplasm. In addition, there are two papers from invited
scientists reviewing the process of bridging the science-farmer gap.
Also contained in the final sections of these proceedings are the following:
(1) the Bean/Cowpea CRSP Global Plan; (2) a roster of Bean/Cowpea CRSP
Management Groups; (3) a roster of participants attending the research meeting,
(4) "An Overview of the Future of the CRSPs" by William Furtick, Agency Director
for Food and Agriculture, provided as background reading for the meeting; and
(5) a brief description of "CRSP Buy-Ins," a procedure by which USAID Missions
in developing countries interested in new or expanded relationships with CRSPs
can become a part of the CRSP community (also provided in advance).
The reports presented by each of the CRSP projects demonstrate how they address
constraints to bean and cowpea production and use identified in the Global
Plan. In their summary, the Brazil/BTI project gives an overview of how they
use insect pathogens to control important cowpea insect pests. Over 300 strains
of cowpea pathogen have been collected, tested and stored. The Dominican
Republic/UWI report discusses how biotechnology is being used to develop ways to
control bean golden mosaic virus. The use of DNA probes to identify different
geminiviruses is outlined. The Cameroon/Purdue project gives a brief summary of
the seed storage survey conducted in northern Cameroon. It also reports how
they developed a simple but effective technology using the heat from the sun to
kill storage insects. The Dominican Republic/UNL paper discusses how resistant
germplasm is being utilized to develop improved bean cultivars to control
important diseases including common bacterial blight, rust, web blight and bean
golden mosaic virus. The Ecuador/UMN project is a new initiative on biological
nitrogen fixation which has begun with a baseline survey assessing fertility
needs, rhizobia soil counts and other related constraints in bean production.
The Guatemala/Cornell paper reviews how selecting for biomass accumulation,
partitioning rate and date of maturity are used to select for high yielding
beans. The Honduras/UPR summary presents an overview of the progress of
breeding for disease resistance in small seeded beans. Resistant material is
being developed to bean common mosaic virus, rust, anthracnose, common blight
and bean golden mosaic virus. The Malawi/MSU project reports how biological and
social scientists interact in the research process. It shows surveys on seed
type preference, preferred varieties and cultural practice information being
used by the plant breeders to develop new bean varieties for Malawi farmers.
The Mexico/MSU program reports that drought tolerant bean lines have been
identified and are being incorporated into U.S. and Host Country breeding
programs. The Senegal/UCR paper reviews their research program and considerable
accomplishment on providing drought and heat tolerance in cowpeas. Also
reviewed are important new technologies for the extension program. The
Tanzania/WSU paper reviews the bean common Mosaic work being conducted at WSU
and the contribution of the farm-level socio-economic survey and variety
development work in Tanzania. The Nigeria/UGA report discusses the newly
developed cowpea mill which is being used to produce cowpea and maize meals
suitable for traditional dishes usually made from hand pounded flour. It also
reports on the nutritional and microbiological evaluation of the processed
cowpea products. The INCAP/WSU project discusses their research to improve the
nutritional quality of beans. Breeding efforts are progressing to develop
germplasm with improved protein digestibility.
After extensive deliberations the following new or expanded research areas were
identified as important for the Bean/Cowpea CRSP to address when additional
funds become available:
1. Increased biotechnology addressing disease and insect resistance
2. Increased germplasm collection, evaluation and utilization
3. More integrated pest management systems (IPM)
4. Expanded research on insect-transmitted viruses, especially white fly
5. Concentrated food nutrition/utilization issues
6. Seed multiplication
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7. Changes in economic and social policies that impact beans and cowpeas (food
policy)
8. Soil conservation management
These research areas have relevance to the United States as well as to the
developing world. Additional support when available will enable the Bean/Cowpea
CRSP to expand research in these important constraint areas.
Other research activities were identified which could best be addressed by
working with other CRSPs. These research activities include:
1. Food processing and utilization with the Bean/Cowpea, Peanut and the
Sorghum/Millet CRSPs (e.g., composite flour)
2. Forage production with the Bean/Cowpea, Small Ruminant and Soil Management
CRSPs
3. Sustainable agriculture project for Africa with the Bean/Cowpea, Nutrition,
Soil Management, Peanut, Sorghum/Millet and Small Ruminant CRSPs
4. Integrated pest management with the Bean/Cowpea, Peanut and Sorghum/Millet
CRSPs
These inter-CRSP activities and the other initiatives proposed throughout this
document will strengthen the Bean/Cowpea CRSP contribution to the alleviation of
hunger and malnutrition in the next decade and on into the next century.
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BEAN/COWPEA CRSP ROSTER OF PROJECTS
COUNTRY OF PROJECT
Title of Project
Host Country Institution
Host Country Principal Investigator
US Lead Institution
US Principal Investigator
BRAZIL
Insect Pathogens in Cowpea Pest Management Systems for Developing Nations
Empresa Brasileira de Pesquisa
Agropecuaria (EMBRAPA)
Ms. Eliane Quintela
Boyce Thompson Institute (BTI)
Dr. Donald W. Roberts
CAMEROON
Preservation of Postharvest Cowpeas by Subsistence Farmers in Cameroon
L'Institut de Recherche Agronomique au Cameroun (IRA)
Mr. Zachee Boli Baboule
Purdue University
Dr. Larry L. Murdock
DOMINICAN REPUBLIC
Biology, Epidemiology, Genetics and Breeding for Resistance to Pathogens
of Beans with Emphasis on Those Causing Bacterial and Rust Diseases
Secretaria de Estado de Agricultura (SEA)
Ing. Agron. Freddy Saladin Garcia
University of Nebraska-Lincoln (UNL)
Dr. Dermot P. Coyne
DOMINICAN REPUBLIC
Molecular Approaches for Control of Bean Golden Mosaic Virus
Secretaria de Estado de Agricultura (SEA)
Ing. Agron. Freddy Saladin Garcia
University of Wisconsin (UWI)
Dr. Douglas Maxwell
ECUADOR
Improving the Productivity of Phaseolus Beans Under Conditions of
Low-Input Agriculture Through Genetic Selection of Host Cultivars
and Rhizobium Strains for Enhanced Symbiotic Efficiency
Institute Nacional de Investigaciones
Agropecuarias (INIAP)
Ing. Gustavo Bernal
University of Minnesota (UMN)
Dr. Peter Graham
GUATEMALA
Agronomic, Sociological and Genetic Aspects of Bean Yield and Adaptation
Institute de Ciencias y Tecnologia Agricola (ICTA)
Dr. Raphael Rodriguez
Cornell University
Dr. Donald H. Wallace
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HONDURAS
Improvement of Bean Production in Honduras Through Breeding
for Multiple Disease Resistance
Escuela Agricola Panamericana (EAP)
Dr. Juan Carlos Rosas
University of Puerto Rico (UPR)
Dr. James S. Beaver
INCAP
Improved Biological Utilization and Acceptability of Dry Beans
Institute of Nutrition of Central
America and Panama (INCAP)
Dr. Ricardo Bressani
Washington State University (WSU)
Dr. Barry G. Swanson
MALAWI
Genetic, Agronomic and Socio-Cultural Analysis of Diversity
among Bean Landraces in Malawi
Bunda College of Agriculture
Dr. A. B. C. Mkandawire
Michigan State University (MSU)
Dr. Wayne Adams (Acting)
MEXICO
Improving Resistance to Environmental Stress in Beans Through Genetic
Selection for Carbohydrate Partitioning and Water Use Efficiency
Institute Nacional de Investigaciones
Forestales y Agropecuarias (INIFAP)
Dr. Jorge Acosta
Michigan State University (MSU)
Dr. Dale Harpstead
NIGERIA
Appropriate Technology for Cowpea Preservation and Processing and
a Study of Its Socio-Economic Impact on Rural Populations in Nigeria
University of Nigeria, Nsukka
Mr. Dickson 0. Nnanyelugo
University of Georgia (UGA)
Ms. Kay H. McWatters
SENEGAL
A Program to Develop Improved Cowpea Cultivars, Management Methods and
Storage Practices for Semiarid Zones
Institute Senigalais de
Recherches Agricoles (ISRA)
Mr. Limamoulaye Cisse
University of California-Riverside (UCR)
Dr. Anthony E. Hall
TANZANIA
Breeding Beans (Phaseolus vulgaris L.) for Disease, Insect and Stress
Resistance and Determination of Socio-Economic Impact
on Smallholder Farm Families
Sokoine University of Agriculture (SUA)
Dr. James M. Teri
Washington State University (WSU)
Dr. Matt J. Silbernagel
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BRAZIL/BOYCE THOMPSON INSTITUTE/EMBRAPA
Donald W. Roberts and Eliane Quintela
Insect Pathogens in Cowpea Pest Management Systems for Developing Nations
Presenters: Donald W. Roberts and Eliane Quintela
Insect pests are major constraints to production and storage of cowpeas and beans
in Brazil and several other Latin American and African countries with large popu-
lations of subsistence farmers. A project emphasizing pest control by biological
methods, particularly by insect pathogens, was initiated with Bean/Cowpea CRSP
support in 1981 by Boyce Thompson Institute (BTI) scientists in collaboration
with the Brazilian Federal Agricultural Research Organization (EMBRAPA). In
addition to U.S. and Brazilian project-supported staff at BTI, a series of Ph.D.-
level U.S. scientists were stationed at the Brazilian National Rice and Bean
Research Center (CNPAF) in Goiania, Goias. Other staff in Brazil included a
Cornell University Ph.D. candidate conducting dissertation research, a project-
trained M.S.-level Brazilian scientist, and several Brazilian technicians and
students. The Brazilian government contributed facilities, administrative
support, senior scientist collaborators and technical help.
Important insect pests of beans and cowpeas in Brazil include the weevil
Chalcodermus bimaculatus, the leafhopper Empoasca kraemeri, the lesser cornstalk
borer Elasmopalpus lignosellus and chrysomelid beetles of the genera Cerotoma and
Diabrotica. Scarabaeid larvae (white grubs) cause crop and turf losses in many
developing nations. These, or closely related insects, are serious agricul-
tural pests in the U.S. as well. Germplasm conservation of entomopathogenic
fungi has been an important element of the project. Almost 300 strains have been
collected, cultured and stored in liquid nitrogen. These isolates are readily
available to scientists worldwide.
Leafhopper Control:
Zoophthora radicans is the principal pathogen of E. kraemeri in central and
southern Brazil. The fungus is mass producible by submerged fermentation and can
be formulated as dry mycelium. Field trials in northeast Brazil with one isolate
failed to initiate epizootics. Laboratory tests have been conducted to define
the effects of temperature on Z. radicans conidial germination, appressorium
formation, host penetration, in vivo development, rhizoid formation, sporulation
and interaction with the host immune system. Direct observation (fluorescent
microscopy) of conidia inoculated onto the leafhopper cuticle indicated that the
maximum rate of appressorium formation occurs at 25C while at 30C appressorium
formation is significantly inhibited. In bioassays, little difference was noted
in percent mortality, in vivo incubation time, sporulation and rhizoid formation
at 20 and 25C. At 30C, however, treatment mortality did not exceed that in the
controls and no rhizoids or spores were produced. Future field trials with this
fungus strain will focus on temperate regions; and a strain from a warm, dry area
will be tested in northeast Brazil. Releases of a Central Brazil strain in New
York induced epizootics.
Hirsutella guyana is the principal pathogen of E. kraemeri in northeast Brazil.
During July 1988, several isolates of this fungus were collected from an
epizootic outbreak discovered in Caucaia, Ceara. The fungus was mass produced
and formulated as dry mycelium and then applied to the undersides of cowpea
leaves in subsistence-level farmers' fields in June 1989. The fungus rehydrated
and underwent sporulation in a manner and at a rate comparable to that observed
on natural fungus-killed leafhopper cadavers, producing a dense mat of conidio-
phores and conidia within two to three days. An unusually low density of
leafhoppers resulted in an insignificant level of pathogen transmission. This
test will be repeated in fields with pest-level populations of leafhoppers.
Soil-Insect Control:
Many of the principal pests of beans and cowpeas pass all or part of their larval
stages within the soil environment. Chalcodermus weevil larvae, after completing
development in cowpea seeds, exit the pods and enter the soil to pupate. Larvae
of E. lignosellus, C. arcuata and scarabaeid beetles are largely subterranean,
feeding on the underground portion of the stem and roots of host plants.
Metarhizium anisopliae and Beauveria bassiana are important natural fungal pathogens
of these insects, and tests have been conducted to asses the microbial control
potential of soil applications.
Weevils: Aqueous suspensions of conidia of M. anisopliae applied at a rate of
1.5 kg conidia/ha to the soil surface under cowpea plants in a field in northeast
Brazil in 1989 resulted in 46 percent infection of sentinel C. bimaculatus larvae
introduced onto the treated soil. These results were similar to those obtained
in 1988 field trials with both M. anisopliae and B. bassiana and indicate that
soil applications of these fungi have the potential to control approximately 30
to 50 percent of weevil larvae entering the soil over a one to two week period.
Use of the fungus, in combination with readily utilizable cultural practices, is
expected to significantly increase yields.
Rootworms. In northern Brazil, larvae of Diabrotica and Cerotoma beetles are
major pests, with well over 100 million dollars spent annually for pesticide
applications. In Brazil, B. bassiana conidia were applied dry to cowpea seeds
which were then planted in small pots. The treatment resulted in 73 percent
mortality of first-instar C. arcuata larvae introduced into the pots after
seedling emergence.
Field plot trials have been conducted in the U.S. to assess the potential of
applying granulated dry mycelium of M. anisopliae and B. bassiana for control of
southern corn rootworm, Diabrotica undecimpunctata, larvae in soil. Two dosage
rates of each fungus (11.2 and 112 kg mycelium per ha) were applied to the soil
surface in 45-cm wide bands in each of eight replicated treatment plots in June.
The inoculum was incorporated into the soil to a depth of 15 cm and corn was then
planted in the treated soil. One month later, viable eggs of D. undecimpunctata
were injected into the soil at the base of each plant. Two sets of untreated
control plots were used: one infested with rootworm eggs and another left
uninfested. In August, corn plants were randomly selected from each plot, and
their root systems were washed and rated (on a scale from 1 to 6) as to damage
from larval feeding. Damage was significantly less in the fungus-treated plots
(damage rated 2.4-3.1) compared to the untreated, rootworm-infested control plots
(rated 3.4) but was substantially greater than the damage sustained by plants in
the uninfested control plots (rated 1.3). The root systems of plants in the
high-treatment-rate plots of M. anisopliae were significantly less damaged (rated
2.4) than plants in the other fungus-treated plots (rated 2.9-3.1).
Determinations were also made of the percentage of abnormally growing (goose-
necked) corn plants, as this deformity is symptomatic of root damage. The high
dose of M. anisopliae was the only treatment which reduced goosenecking to a
level significantly lower than that observed in the infested control plots (viz.,
21 vs. 46 percent). The emergence of adult rootworm beetles on a per plant basis
was monitored during August and September. The high dose of M. anisopliae was
most effective in reducing adult emergence (30 percent fewer beetles emerged from
this treatment than from the infested control).
Changes in fungal inoculum levels were monitored by plating soil samples onto a
selective medium. During the first four weeks following treatment, fungus soil
titers rose due to sporulation of the applied mycelium. Titers reached highest
levels in the upper few centimeters of the soil profile, probably due to aeration,
and titers of B. bassiana were commonly higher than those of M. anisopliae. The
amount of fungal inoculum began to decrease during the latter half of July (when
the introduced larvae were active); however, even at the end of the season (21
September), titers were still above their initial levels.
White grubs. The Japanese beetle, Popillia japonica, is a pest of turf and
ornamental plants throughout the northeastern United States. This species is a
useful model for many scarab pests of the Third World because its life cycle is
typical of the group. Assays conducted during 1989 tested the effectiveness of
M. anisopliae dry mycelium and conidia preparations against P. japonica larvae in
soil at two different levels of moisture (40 and 65 percent saturation) and
temperature (15.5 and 20C). Mortality occurred more rapidly and reached higher
proportions among larvae incubated in soil inoculated with dry mycelium than in
soil treated with conidia. These results were unexpected since conidia are the
infectious units and two to three days are required for sporulation of the
rehydrated dry mycelium. Conditions of 40 percent saturation and 20C were
generally most favorable for infection.
Lesser stalk borer. In recent screenhouse tests, application of conidia of
M. anisopliae and B. bassiana to the stems and soil surrounding the stems of
cowpea seedlings at rate of 2.9 x 106 conidia/cm2 caused greater than 85 percent
mortality of neonate E. lignosellus larvae which hatched from eggs placed on the
soil near the plants.
Training and Institutionalization:
A functioning, well-equipped microbial control laboratory has been established at
CNPAF. In 1989, CNPAF instituted an integrated pest management (IPM) program.
The Bean/Cowpea CRSP microbial control/insect pathology project, at CNPAF's
invitation, has become an integral part of this program. Two of the HC PIs have
received graduate training with CRSP staff. (Bonifacio Magalhies is completing a
Ph.D. degree at Cornell University/BTI and Eliane Quintela obtained an M.S. degree
by completing course work at the University of Sio Paulo (Piracicaba) and thesis
research at CNPAF with CRSP scientists.) A total of five Brazilian students have
participated in M.S. degree programs, and one U.S. and one Brazilian student are
completing Ph.D. degrees. Three of the seven are women. Several post-
baccalaureate students have served in research internships at CNPAF for periods
of up to one year. In addition, six short courses (one to two weeks) have been
used to train approximately one hundred students (47 percent female) from Brazil
and five other Latin American nations on microbial control and entomology.
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Question and Answer period: BRAZIL
Q: How did you spray Beauveria in the field and how did you verify that no
natural epizootic of this organism would have occurred in the field?
A: We used a pressurized sprayer similar to those used for insecticides and
chose a field site where it was highly unlikely that an epizootic of
Beauveria would occur.
Q: Do you have plans to extend your research and technology to Africa?
A: We are interested in working in Africa on the control of insect pests. This
could include cowpea aphids, flower thrips and soil insects.
Q: Are there any hazards to the farmers from the fungi considered for use in
insect pest control, either in handling the materials or eating plants on
which the materials have been applied?
A: The only potential problems the presenter could think of are allergies--but
they are not aware of any specific cases where problems occurred.
Q: Have toxicology tests been conducted in fungal agents for controlling insect
pests?
A: Toxicology tests have been conducted which indicate no problems to people,
but there may be problems to specific cold-blooded animals such as tortoises
under cold-stress conditions such as in zoological gardens.
Q: Do these fungal agents have any negative effects on beneficial insects?
A: There are some cases of negative effects but honey-bee hives are not harmed.
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CAMEROON/PURDUE UNIVERSITY/IRA
Larry Murdock and Zachee Boli Baboule
Preservation of Postharvest Cowpeas by Subsistence Farmers in Cameroon
Presenters: Larry Murdock and Zachee Boli Baboule
Storage pests are a major constraint to the availability of cowpeas as food in
developing nations. One major pest, the cowpea weevil, Callosobruchus maculatus,
enters storage granaries at harvest in low numbers but reproduces rapidly--each
generation is completed in a few weeks, each female reproduces herself twenty-
fold each generation--after a few months, unprotected cowpeas in stores can
become riddled, inedible and worthless. The IRA/Purdue CRSP project is devising
implementable technologies to reduce losses caused by the cowpea weevil and other
storage pests. We developed our research with three strategic assumptions,
namely: (1) that we should listen to the people in the countryside who grow,
store and utilize cowpeas, indeed, that we must learn from the people if our
research is to produce relevant results and implementable technologies; (2) that
we should develop several alternative storage technologies to meet the needs of
the diverse ethnic groups in the region who follow various cowpea production and
storage patterns, this variety of technologies being combinable in different ways
to meet the range of needs; and (3) that we should engage in short-term, mid-term
and long-term research.
Survey:
Northern Cameroon, where our project is based, has a variety of ethnic groups and
multiple systems of cowpea production, storage and utilization. To improve
cowpea storage it is essential that we have first-hand knowledge of the people
concerned, their relationship to cowpea and their perception of the problem. In
particular, we need to have objective information about (1) cowpea storage
practices of farmers of different ethnic groups and socio-economic strata,
including how long cowpeas are stored, in what form and what measures are taken
to reduce losses; (2) what the different storage pest species are at different
times during the storage season. To obtain this information, Dr. Jane Wolfson
has carried out three month-long surveys in northern Cameroon over the last three
years. The results have provided us with baseline data and a framework for our
research.
The surveys involved (1) interviews with farmers, stores and users of cowpeas in
the area within an 80 km radius of Maroua; (2) observations of cowpea storage
techniques in use; and (3) sampling of stored cowpeas to determine degrees of
damage and the nature of the insect problem. Findings include evidence that:
1. Women play important roles in all aspects of cowpea production, storage and
processing;
2. The cowpea weevil is the principal insect pest for long-term storage but that
another bruchid, Bruchidius atrolineatus, is a pest of cowpeas at and shortly
after harvest;
3. Cowpeas are generally stored in pod form for an extended period on pole
platforms called dankis, then threshed and stored as seed in various ways;
-11-
4. Low-resource farmers are well aware of storage weevils and utilize a variety
of "traditional" storage techniques designed to stop their losses. A common
technique is to store the threshed cowpeas with ash, with herbs or a
combination of the two;
5. Cowpea hay is an important forage;
6. Many farmers utilize green and dried cowpea foliage as a vegetable.
Knowledge that farmers commonly store cowpeas in pod form for long periods
encourages us to pursue our long-term goal of combining seed and pod resistance
through breeding/selection. Combined pod/seed resistant cowpea types will
probably be acceptable because they are compatible with storage techniques people
are already using. Knowledge that farmers often store their cowpeas in ash has
prompted us to verify the value of the technique and develop a recommended
procedure. Knowledge that cowpeas are eventually threshed and stored in seed
form has encouraged us to see threshing time as a window of opportunity for using
solar radiation to eradicate existing bruchid infestations. Confirmation that
there are two bruchid pests, not one, will help us direct our research in ways
that will enable us to deal appropriately with both pests.
Storage Technology Development or Testing
Solar technology: Experiments conducted at Purdue University revealed that
exposing cowpeas to temperatures of >57*C in an oven for 1 hour killed cowpea
weevil eggs, larvae and pupae living within the seeds and adults living among the
seeds. Using only the sun's rays and a simple heater constructed from cheap,
widely available materials, we demonstrated the feasibility of using solar energy
to eliminate cowpea weevil infestations from cowpea stores. The temperatures and
exposure times necessary to disinfest cowpeas had no significant effect on the
cooking time and percentage germination of cowpea seeds.
In Cameroon, simple solar heaters were constructed using locally available and
affordable materials that produced and maintained temperatures of >57C within
seeds during the initial, coolest part of the cowpea storage season (November to
January). Additionally, the effectiveness of these heaters in eliminating
C. maculatus infestations in stored seeds was demonstrated. Solar disinfestation
of cowpea stores using this simple technology represents a new approach to
preserving cowpea stores which may be useful at the level of subsistence farmers
in developing nations, not only for cowpea, but for other stored grains as well.
Currently we are developing a simple solar heater package and protocol and will be
testing it in our network of farmer-cooperators in Cameroon during the coming
year.
Ash storage: Results from experiments conducted at IRA facilities in Maroua,
Cameroon and Purdue University confirm that wood ash, when mixed in equal volumes
with cowpea seeds, effectively stops cowpea weevil population growth. Larvae
living within the seeds when the seeds are put into ash continue to grow and
develop, but the adults have difficulty emerging from the seed, crawling through
the ash, finding mates and oviposition sites. When the volume ratio of ash to
cowpea seed is reduced below 0.75, however, ash begins to lose its effectiveness
to retard cowpea weevil population growth. Results also show that an uninfested
store of cowpeas can be protected from cowpea weevil infestation by a 3 cm layer
of wood ash layered on its surface. Currently we are developing a simple ash
storage protocol that can be used by low-resource farmers to preserve cowpeas
-12-
from bruchids. We hope to test this protocol in the coming months. We plan
further research into the effectiveness of wood ash from various species, as well
as ash from animal dung.
We anticipate that it may be possible in the future to combine solar heating to
eradicate weevil infestations together with ash storage to prevent reinfestation.
This combination of methods should effectively reduce losses and allow long-term
storage of cowpeas free from further damage.
Botanicals: The effect of various botanicals on C. maculatus adult emergence and
oviposition were studied in Maroua, Cameroon. Neem oil and shea nut oil
(Butyrospermum parkii [G. Don] Kotschy) were effective even at quite low concen-
trations. The powders and flowers of nine other botanicals tested did not appear
to be markedly effective, although all did have a statistically demonstrable
effect on adult emergence and oviposition. With the exception of the two oil
treatments, the practical value of other botanicals is unclear. Some of the
effect of most botanicals tested appeared to result from mechanical effects on
behavior, similar to wood ash.
Development of Seed and Pod Resistant Cowpea Cultivars:
One of our longer-term goals is to develop, through plant breeding, varieties
which combine seed and pod resistance and which are adapted to conditions in
northern Cameroon. To achieve this goal, two major research thrusts are required:
1. Pod and seed resistance screening to identify or develop varieties possessing
seed or pod resistance to C. maculatus;
2. Yield trials to identify varieties which are adapted to growing conditions,
preferences and practices in northern Cameroon. Yield trials, begun during
the Georgia phase of the project and continuing under Purdue, have assessed
the performance of large numbers of locals and exotic lines and laid a good
foundation for the development of the planned breeding work for combined seed
and pod resistance.
Screening for resistance to cowpea weevil in cowpea pods:
A major effort toward screening for seed and pod resistance has been carried out
during the past year. Several cowpea varieties developed by the International
Institute of Tropical Agriculture (IITA) possess seed resistance to C. maculatus
(derived from local cultivar TVu 2027). We screened intact pods of several of
these lines in the laboratory (1) to determine if any possess pod resistance in
addition to seed resistance and (2) to ascertain whether this resistance was due
to seed factors, pod-wall factors or an interaction between the pod and seed
factors. Physical measurements were made of several pod and seed characteristics.
Numerous seed resistant lines gave evidence of also having pod resistance. The
primary manifestation of pod resistance was pre-establishment larval mortality
(PLM)--those larvae dying after egg hatch but before penetrating into the seeds.
PLM ranged from 57.9 percent to 99.4 percent among the 30 varieties examined.
Several varieties combined seed and pod resistance and exhibited overall pod and
seed mortality of between 95.3 percent and 99.9 percent. This combination of
seed resistance and pod resistance should represent a very durable form of weevil
resistance.
-13-
We developed a practical method for measuring pod resistance to breakage
(breakage from handling plus pod dehiscence). Although resistance to breakage is
a necessary characteristic for overall pod protection, this factor alone is not
sufficient to confer a maximum level of whole pod resistance. Other factors
contribute importantly to whole pod resistance. By combining pod resistance with
seed resistance, a higher level of overall resistance is attainable and the
resistance may be more durable.
Measurements were made of (1) the space surrounding individual seeds in the pod;
(2) pod wall thickness; (3) pod wall strength; (4) pod:seed ratio; (5) seed coat
thickness; and (6) seed coat texture. Seed coat thickness and texture were the
factors most highly correlated with pre-establishment larval mortality. Our
results suggest that interactions between pod wall and seed coat characteristics
may play an important role in pod resistance to C. maculatus.
We anticipate that the use of seed and pod-resistant varieties, combined with
solar disinfestation and ash storage, could be implemented by low-resource
farmers and provide, at low cost in materials, money, time and effort, a sub-
stantial degree of protection to cowpeas in storage over the long term. Other
techniques, such as drum storage with insecticides, double-bagging, use of co-
storage with botanicals or oil treatments, may be integrated into this system of
storage as well.
-14-
Question and Answer period: CAMEROON
Q: Does the ratio of ash/cowpea in storage influence the taste of the cowpea
when cooked?
A: The ratio that we are recommending is one ash/one cowpea by volume and is
presently used by some farmers in Cameroon and considered to be acceptable.
Q: Why isn't ash storage used more widely by farmers?
A: This may be because ash storage is sometimes not effective.
Q: Do farmers differentiate between storing cowpeas for use as seed vs. for use
as food?
A: Farmers using ash storage may not differentiate, but farmers using less
effective methods for storing cowpeas as food may use ash storage for storing
cowpeas for use as seed.
Q: What about using oil to protect cowpea seed in storage?
A: One ml of vegetable oil per 100 g of seed will protect cowpea to some extent
by suffocating the weevils, and Jane Wolfson found one person out of 300
persons interviewed to be using oil to store cowpeas in Cameroon.
Q: Could the arcelin compound that occurs in common bean seed protect cowpea
seed against the cowpea weevil?
A: We are investigating ways for testing this possibility.
Comment: Researchers should develop a menu of different control methods for
cowpea weevil to cover the many different economic and social circumstances under
which cowpea grain is stored at the village level and in stores and markets in
Africa.
-15-
DOMINICAN REPUBLIC/UNIVERSITY OF NEBRASKA-LINCOLN/SEA
Dermot P. Coyne and Freddy Saladin Garcia
Biology, Epidemiology, Genetics and Breeding for Resistance to Pathogens
of Beans with Emphasis on Those Causing Bacterial and Rust Diseases
Presenters: Dermot P. Coyne, James R. Steadman,
James S. Beaver and Freddy Saladin Garcia
Collaborative research cannot be conducted without Host Country scientists and
facilities. In 1982 these were insufficient in the Dominican Republic (DR) legume
program. Through training (ten advanced degrees), improvements at the Arroyo Loro
Station and increased government support, there is an enthusiastic research team
capable of collaborating on reducing constraints to bean production as well as
attracting other sources of support (i.e., funding to initiate Caribbean Coopera-
tive Agricultural Research Network). Continued training will be needed along
with collaborative research efforts to improve the quality of research in the DR.
Basic information to guide pest management strategies and breeding approaches as
well as improved bean cultivars for small-scale farmers will be the pay off.
Linkages with other CRSP projects and CIAT bean networks will be expanded.
Diseases of beans, particularly common bacterial blight (CBB), rust (RU), web
blight (WB), and bean golden mosaic virus (BGMV), are major constraints to bean
yields and seed quality in the DR. The overall objectives were to identify
resistant germplasm and determine pathogenic variation, to conduct epidemio-
logical and genetic studies, to develop resistant cultivars, to improve research
facilities and capabilities, to train personnel and to educate graduate students.
The expected impact is (1) improvement of breeding programs and disease manage-
ment strategies in the DR, U.S. and other CRSPs and (2) improvement of yields and
income to small-scale farmers in the DR.
Major Results by Constraint:
Common bacterial blight (CBB): (1) A semi-selective medium (MXP) was developed
(a "breakthrough") for isolation of Xanthomonas campestris (Xcp) from common
blight infected bean tissue and infested soil. (2) The MXP medium was used to
study epiphytic populations of Xcp on leaves of different bean genotypes (Univer-
sity of Nebraska-Lincoln [UNL], DR) and weeds in and around bean fields (DR).
Resistant bean genotypes supported lower populations of Xcp than susceptible
genotypes. A relationship between disease incidence and epiphytic populations
(105 cfu/ml) was established. A common bean breeding line BAC-6 (Brazil) was
found to have highly resistant pods and no seed infection when inoculated with
Xcp. Many pathogenic Xcp strains were found on the weed Echinoclon colonum in
different locations in the DR. (3) The MXP medium was also used to study survival
of Xcp in infested bean debris incorporated in the soil or on the soil surface
(DR). Survival was limited to one month in the soil but Xcp was isolated after
five months from surface debris. (4) Heterogeneity and randomness of Xcp strains
was observed using bacteriophage typing (DR). (5) Strains of Xcp were differen-
tiated into pathogenic races based on their reactions (hypersensitive/compati-
bility) on cotyledons of tepary genotypes, but differential reactions of this
type were not observed on leaves and pods of both tepary and resistant common
bean germplasm; a bean genotypes Xcp strain statistical interaction was observed
on leaves and pods (differential compatibility reactions). (6) A rapid and
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reproducible detached leaflet bioassay was developed to isolate pathogenic and
virulent mutants of Xcp, Co-inoculation experiments of Xcp and bean common
mosaic virus (BCMV) on bean showed that screening for reaction to those pathogens
can be done simultaneously but, because of interactions of Xcp and the rust
pathogen, it is recommended to inoculate separate leaves., (7) The determinate
plant habit of the Pompadour germplasm was associated with increased and severe
necrotic reaction to Xcp but with reduced leaf chlorosis compared to indetermi-
nate Pompadour germplasm. Some bean genotypes developed a rapid leaf chlorosis
(high levels of C2H4) when inoculated with Xcp. (8) Photoperiod affected the
adaptation and also the reaction of some germplasm to Xcp. (9) Tepary and common
bean germplasm was identified with high resistance to Xcp. (10) Leaf and pod
disease reactions to Xcp were inherited quantitatively with low narrow sense
heritabilities and were not associated. Earliness and determinate plant habit
were associated with susceptibility to Xcp. (11) Red mottled Pompadour, Great
Northern (GN) and Pinto lines have been developed with resistance to Xcp.
Rust: (1) A new common set of rust differentials was used to monitor and study
rust variability in the DR, UNL and elsewhere. The DR rust races differed from
those in the state of Nebraska. Greater virulence, as measured by the number of
differential cultivars with large pustules, occurred in the DR rust populations.
The "cluster" patterns indicated similarity of DR and Florida isolates and also
similarity of midwest U.S. isolates. (2) Positive correlations were observed
between rust race nonspecific resistance (reduced rust intensity) in trifoliolate
pubescent leaves (long straight abaxial hairs) of PC-50 (DR), Jamaica Red and
Alubia selections (Argentina). The glabrous primary leaves of these varieties
were highly susceptible to many rust races while the hairy leaves were observed
to be resistant in field studies. (3) The pubescent trait does not appear to be
influenced a great deal by environment; however, genetic background can reduce
rust resistance effects. A rating scale to measure pubescence was devised.
Plastochron index is a superior indicator of leaf development. Rust pustule size
showed a negative correlation with leaf age and was also influenced by nutrition
and pH of the media. Bean genotypes growing in a calcareous soil (high pH) had
smaller pustule sizes than when grown in potting media. (4) Single plant selec-
tions within the Pompadour landrace were made for specific and nonspecific (leaf
pubescence) rust resistance. Some components of this landrace were highly
susceptible. (5) Specific resistance in Pompadour Checa was controlled by one
or two major genes depending upon the cross and rust isolates used. Different
major genes controlled the leaf pubescence in rust resistant Jamaica Red than in
PC-50. (6) Rust resistant Pompadour, black (H-270) and white bean-VO31 (DR,
University of Puerto Rico [UPR]) and GN (UNL, USDA) and Pinto dry beans (UNL) have
been developed. GN BelNeb rust resistant -1 and -2 (USDA, UNL) were released for
resistance to 33 rust and to Xcp and BCMV.
Bean golden mosaic virus (BGMV): (1) Bean lines DOR303 and A429 (CIAT), which
were reported to have field resistance to BGMV, were found to have much lower
feeding and oviposition preference to white flies than BGMV susceptible lines.
(2) A leguminous weed species was found to serve as an alternate host for BGMV.
(3) Two Pompadour selections (DR) were found to have high leaf resistance
(tolerance to BGMV but pod set and seed development was limited in severe BGMV
nurseries. Early maturing lines appear to have less BGMV than later lines. The
CIAT lines DDR301, DOR302, DOR303, A471, A420 and A429 had high field tolerance
to BGMV.
Web blight: (1) The fungus causing web blight was found to be transmitted
through the seed. (2) Web blight was more severe on determinate beans
-17-
intercropped with corn than in monoculture. (3) Red mottled lines have been
selected with low incidence (5-11 percent) of web blight infection.
Ashy stem blight: (1) Variations in virulence of isolates of Macrophomina
phaseolina (Mp) was observed and an effective inoculation method was developed.
(2) Three lines from the Pompadour germplasm collection showed moderate levels of
resistance to all Mp isolates.
Adaptation and yield improvement of different grain types: (1) Small seeded
indeterminate dry bean lines had higher and more stable yield than large seeded
determinate lines (DR). Narrow sense heritabilities were generally low for
yield, yield components and several morphological traits in progenies derived
from crosses of the above plant types. (2) A breeding strategy to select and
develop GN and Pinto dry bean lines for multiple disease resistance based on
pathogen interactions, seed quality, adaptation and yield was developed (UNL).
Promising lines were developed and will be released in 1990. (3) Lines with
tolerance to high temperature and high BNF were identified (DR, UPR). Indeter-
minate, early, high-yielding Pompadour types are being developed. (4) High
outcrossing (16-39 percent) was observed in a do dwarf bean mutant line which has
potential for population improvement. (5) Enough seed has been increased in the
DR of the new PC-50 (Pompadour Checa) to supply the country's needs in 1990. It
is proposed to release new rust resistant white seeded and black seeded beans in
1990 (DR). Small white seeded varieties Arroyo Loro (DR) and Monument (UNL) were
released in 1985.
Implications for the Small-Scale Farmer:
(1) The new improved PC-50 variety will provide higher yields to the growers and
better quality grain to the consumer. The introduction of new black seeded and
white seeded varieties in 1990 will also improve the yields and disease resis-
tance of these grain types for growers. The future introduction of DR grain
types with multiple disease resistance, indeterminate plant habits, earliness and
higher yields should be a major contribution to dry bean growers (DR). (2) The
adoption of sanitation (removal of debris), rotation, removal of weeds (host of
Xcp) and burying Xcp infested bean debris will reduce common blight without much
added expense. (3) Removal of specific weed hosts of BGMV, early planting and
use of earlier maturing bean varieties can reduce losses due to BGMV. (4) Use of
disease-free seed (common blight, web blight) can reduce yield losses and prevent
spread of the diseases. (5) The introduction of bean varieties with multiple
disease resistance should benefit the farmer by reducing costs of production,
stabilizing yields and reducing pesticide usage.
Future Research:
(1) Determine the inheritance of the different types of leaf reaction to Xcp and
also of resistance to seed infection in common and tepary beans. (2) Transfer
major genes determining the reaction to Xcp in tepary to common beans through
interspecific hybridization and congruity backcrosses. (3) Develop a protocol
for regeneration of common bean and tepary. Develop transgenic common beans with
resistance to Xcp. (4) Genes controlling leaf pubescence should be incorporated
into glabrous bean types with specific resistance. Additional information is
needed on the inheritance of pubescence and the mechanism of nonspecific
resistance. The possible effects of pubescence versus glabrousness on bean
performance needs to be evaluated in isogenic lines in diverse environments.
(5) Additional screening should be done in Pompadour to identify higher levels
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of resistance to BGMV (DR). The inheritance of the reactions to web blight
and BGMV and also their association with other traits needs to be investigated.
(6) Possible biocontrol for the web blight organism needs to be studied.
(7) Heat tolerant lines with resistance to CBB need to be developed in the DR.
(8) Multiple disease resistant, higher-yielding indeterminate red mottled lines
will be developed for small-scale DR farmers and development of cultivars for
UPR and UNL will be continued. (9) Impacts of PC-50, other newly developed
cultivars and disease control strategies need to be documented.
Linkages:
Present linkages are with personnel in the Regional Research Project W-150,
CIAT, North Dakota State University (K. Grafton), Michigan State University
(J. Kelly) and Bean/Cowpea CRSP projects in Dominican Republic/University of
Wisconsin, Honduras/UPR and Tanzania/Washington State University-Prosser. New
linkages will be established with personnel in Oregon State University (tissue
culture and Restriction Fragment Length Polymorphism [RFLPs]), University of
California-Davis (RFLPs), Michigan State/Malawi Bean/Cowpea CRSP project,
CIAT/African Bean Network, CIAT/Central America and Caribbean (COSUDE) and
Caribbean Co-operative Agricultural Research Network.
-19-
Question and Answer period: DOMINICAN REPUBLIC (Coyne)
Q: Have you used the bean golden mosaic resistant lines from Los Mochis, Mexico?
A: Not yet, but Rafael Solinas is preparing a nursery containing these lines for
testing throughout the Caribbean.
Q: How did you identify low seed transmission of common blight in BAC6?
A: Graduate student Ammad Aggour used several different inoculation methods
(blossom, pod) and BAC6 was the only genotype with this low level of seed
transmission.
Q: What is the inheritance of dense pubescence and are there any undesirable
traits associated with dense pubescence?
A: Results from the University of Nebraska and the University of Puerto Rico
have found a fairly simple inheritance involving one to two genes. We have
not observed association with undesirable traits although there is a need to
better understand the relationship between pubescence density and white flies.
Q: Why was PC-50 selected as a pure line rather as a heterogeneous mixture?
A: PC-50 was selected for superior performance and disease resistance in a wide
range of environments in the Dominican Republic. There are some bureaucratic
problems in releasing a mixture of genetypes in the Dominican Republic. This
observation is a very valid issue.
-20-
DOMINICAN REPUBLIC/UNIVERSITY OF WISCONSIN/SEA
Douglas P. Maxwell and Freddy Saladin Garcia
Molecular Approaches for Control of Bean Golden Mosaic Virus
Presenters: Douglas P. Maxwell and Freddy Saladin Garcia
Bean golden mosaic geminivirus (BGMV) and other bean-infecting geminiviruses
(e.g. bean dwarf mosaic geminivirus [BDMV]) are major constraints on bean
production in subtropical and tropical Americas. Some fields experience 100
percent losses. In the Host Country of the Dominican Republic, the severity of
BGMV is increasing because of changing agricultural practices, which favor
increases in the population of the whitefly insect vector, Bemisia tabaci, of
BGMV. Evidence indicates that considerable genetic variation exists among BGMV
strains causing the disease in the field and that this variation will be a major
complicating factor in attempts to control this disease by classical breeding
methods. Our project has the following major objectives:
1. Molecular characterization of bean geminiviruses;
2. Development of general and strain-specific DNA probes for rapid
identification of geminiviruses-infecting weeds, crops and beans;
3. Evaluation of virus-derived resistance schemes for the eventual production
of beans resistant to geminiviruses.
Progress to Date:
Molecular characterization of bean qeminiviruses: Isolates of BGMV thought to
represent the greatest genetic diversity were obtained from Brazil (BGMV-BZ), the
Dominican Republic (BGMV-DR) and Guatemala (BGMV-GA). Additionally, an isolate
of bean dwarf mosaic virus from Colombia was characterized since this geminivirus
causes dwarfing but no golden mosaic symptoms and is very important in Argentina.
Each of these virus isolates was cloned and sequenced. The genome for each was
shown to be composed of two distinct DNA components, designed A and B. Component
A had four open reading frames (ORFs) and component B had two ORFs. This genome
organization is similar to that described for other bipartite geminiviruses such
as tomato golden mosaic geminivirus. Sequence similarity between BGMV-BZ, which
is not mechanically transmitted, and the two mechanically transmitted isolates,
BGMV-DR and BGMV-GA, was about 75 percent, which is the percent sequence similar-
ity between BGMV-BZ and tomato golden mosaic geminivirus. Therefore, we concluded
that two distinct strains of BGMV exist. BDMV is not closely related to either
of these two distinct strains of BGMV and should be considered a separate virus.
Our results indicate that breeding for disease resistance will require evaluation
of germplasm using these two strains. We have also obtained full-length clones
of another geminivirus, bean calico mosaic, from beans grown in Mexico and this
virus is being characterized.
Development of general and strain-specific DNA probes: Nucleic acid spot
or squash hybridization methods were developed to detect geminiviruses or a
particular strain of bean-infecting geminiviruses. This technique involves
squashing a 1 cm diameter leaf disc onto a special nylon membrane, which
binds DNA. This membrane can be mailed or stored for later processing. The
membrane with the squashed leaf tissue is treated to denature the DNA (create
-21-
single-stranded DNA) and then placed in a hybridization solution of probe DNA,
which is also radioactive and single stranded. Complementary DNA sequences anneal
(hybridize) and the radioactivity is detected by exposure of the membranes to
X-ray film. This technique has been effectively used to detect BGMV in samples
that had typical golden mosaic symptoms from Puerto Rico, Dominican Republic,
Brazil, Guatemala, Colombia and Honduras.
General probes have been developed which will detect a broad range of gemini-
viruses from beans, other commercial crops and weeds. Also, strain-specific
probes are being developed and initially the B component has served as a useful
probe to distinguish between the different bean-infecting geminiviruses. These
probes will be used to determine the extent of genetic variability of BGMV
isolates from a given region as well as to determine which weeds or crops are an
important reservoir of bean-infecting geminiviruses. To date, several weeds have
been found to contain geminiviruses, but only one weed, Rhynchosia minima, from
the Dominican Republic has hybridized to the strain-specific BGMV-DR probe. It
also hybridized to the other strain-specific probes which indicates that it might
be a mixed infection or a unique geminivirus infecting this weed. Major efforts
are planned for the future to use these probes to study variability and weed
reservoirs in Dominican Republic, Mexico, Honduras, Brazil and Argentina.
Virus-derived resistance scheme for transgenic plants: Recent experiments with
RNA plant viruses indicate that viral sequences can be used to create transgenic
plants which are resistant to the virus. This approach is facilitated by an
understanding of the functions of the viral genome, and this requires the use of
infectious clones of the viruses. Many attempts at infecting beans with cloned
viral DNAs by mechanical inoculation failed. However, cloned DNAs of the four
geminiviruses, BGMV-BZ, BGMV-DR, BGMV-GA and BDMV, were infectious when inoculated
into beans by electric discharge particle acceleration. Viral DNA of BGMV-GA has
been mutated in two genes of component A, and these mutated DNAs and wild-type
component B have been introduced into beans by particle acceleration. Mutational
analysis will be continued to determine the functions of various domains in the
replication, symptom development and movement of the virus in plants. Also, the
possible involvement of certain genes in insect vector transmission can be studied.
Future Research Directions:
Molecular characterization of geminiviruses: Our efforts will continue on the
molecular characterization of bean-infecting geminiviruses. Bean calico mosaic
geminivirus from Mexico will be partially cloned and sequenced. Also, the gemini-
virus in the weed, Rhynchosia minima, will be studied to determine if it is the
same virus that infects beans in the Dominican Republic.
Application of geminiviral DNA probes to epidemiological studies: The general
and strain-specific probes will be used to determine the importance of weeds as
reservoirs of bean-infecting geminiviruses and to determine the variability of
bean-infecting geminiviruses in a specific region. These efforts will concen-
trate on the Dominican Republic, Honduras, Mexico, Brazil and Argentina.
Virus-derived resistance schemes for transgenic beans: Much of our effort will
be devoted to understanding the functions of the various DNA regions of the virus
genome and developing approaches to utilize this information to create resistant
transgenic beans. Also Agracetus Inc. will modify the methods, which were
developed for soybeans, to transform beans. Initial experiments have indicated
that this will be possible.
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Breeding and inheritance of resistance to bean infecting geminiviruses:
Germplasm will be evaluated in the field in the Dominican Republic and in growth
chambers at the University of Wisconsin. Since immune cultivars exist for BDMV,
an inheritance study has been initiated.
We will continue to provide training in molecular biology for visiting scientists
in our laboratory at the University of Wisconsin and attempt to maintain the
linkages which have been established during the past three years. New cooper-
ative efforts will be initiated with scientists in Jamaica, Honduras, Nicaragua,
Mexico and Argentina.
-23-
Question and Answer period: DOMINICAN REPUBLIC/Maxwell
Q: Why has the importance of BGMV been increasing in the Caribbean Basin?
A: The population of the white fly vector has increased because more hosts of
this insect have been planted as part of an effort to increase production of
such crops as tomatoes, peppers and melons.
Q: Are the infectious clones you have sequenced representative of the BGMV in a
particular region?
A: Recently, Maria Rojas and Robert Gilbertson have used polymerase chain
reaction techniques to show that the BGMV DNA clones from the Dominican
Republic are typical of isolates from five diverse geographical regions. Now
this needs to be done for isolates from Central America and Brazil.
Q: When do you think transgenic bean plants will be produced?
A: David Russell from Agracetus, Inc., Middleton, Wisconsin, is using the
particle gun to transform beans with the coat protein gene from BGMV-GA. It
is expected that the seed-lines with the coat protein gene should be produced
by July 1991.
-24-
ECUADOR/UNIVERSITY OF MINNESOTA/INIAP
Peter Graham and Gustavo Bernal
Improving the Productivity of Phaseolus Beans Under Conditions
of Low-Input Agriculture Through Genetic Selection of Host Cultivars and
Rhizobium Strains for Enhanced Symbiotic Efficiency
Presenters: Peter Graham and Gustavo Bernal
While this project has been underway for only a year, it builds upon an earlier
Bean/Cowpea CRSP program in Ecuador, on a limiting factors grant between the
PI and INIAP, on collaborative studies between INIAP and NifTAL, and on basic
studies that were already underway in the U.S. laboratory. Where appropriate,
aspects of these ongoing studies will be mentioned alongside new initiatives in
this report.
Beans are a major commodity in Ecuador with some 50,000 ha sown annually for an
average yield of 560 kg/ha. Crop production is centered on holdings of less than
3 ha and at altitudes from 1300 to 2300 m above sea level. Technical inputs are
limited, with the crop commonly sown without fertilization. Despite this there
has been little done to improve rates of nitrogen (N2) fixation. Major problems
limiting N2 fixation in beans are likely to include:
1. Cultivars limited in capacity for N2 fixation and susceptible to insect and
disease pests;
2. Soil nutrient deficiencies;
3. Competition for nodulation sites between indigenous organisms and inoculant
strains;
4. Problems in the use of chemical seed treatments.
Given these constraints, we believe this program should have a dual focus:
(1) to enhance N2 fixation in Phaseolus vulgaris; and (2) to improve bean yields
and profitability in Ecuador. As the only project within the CRSP which is to
emphasize nitrogen fixation, we foresee considerable interaction in our nitrogen
fixation work with other projects and programs, and in particular with CIAT.
Activities to date have emphasized four main areas:
1. A baseline study to better define problem areas: The five main bean producing
areas of Ecuador will eventually be sampled. To date attention has been
focused on Imbabura province. Soils from 49 farms have been analyzed, with
soil zinc and manganese levels below deficiency levels in 65-70 percent of
them. Iron is also likely to be limiting in some 35 percent of soils. In an
earlier study undertaken by the Cornell group, 83 percent of the farmers in
this region reported the use of foliar- rather than soil-applied fertilizers.
Most, but not all, foliar preparations contained micronutrients. We may have
to give this problem more attention than anticipated.
As part of the same study, most probable number counts of rhizobia in soil
have been made. Most soils had more than 104 rhizobia per g of soil, a level
at which indigenous organisms are sure to interfere with nodulation by
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inoculant rhizobia. A dot-blot serological method was developed to type the
indigenous organisms and to select from among them a common serogroup to be
used in the evaluation of cultivars for host restriction of nodulation.
2. Cultivar evaluation for traits affecting N2 fixation: Studies on cultivar
variation in traits affecting nodulation and nitrogen fixation have been
initiated. Traits being considered include speed in nodulation, nodulation
efficiency, nodule duration and activity, phosphorus use efficiency and
tolerance to low pH. Ninety cultivars, including a number previously
identified as active in N2 fixation, have been evaluated for earliness in
nodulation. Superior lines have included N80014 (MSU), 21-58 (UWI), Preto
143 (Brazil) and Negro Argel. Preto 143 is of particular interest because of
its known tolerance to acid soil conditions. A similar number of cultivars
have been evaluated for growth at low soil phosphorus using the aluminum
phosphate/sand system of Gabelman and co-workers. A breeding program to
combine traits contributing to enhanced N2 fixation with sources of disease
resistance will initiated in 1991.
3. "Competition" for nodulation sites in Phaseolus beans: In soils with abundant
indigenous rhizobia, inoculant strains rarely produce more than 5-10 percent
of the nodules, and yield response to inoculation is uncommon. This has been
perceived as a problem of "competition for nodulation sites" between the
inoculant strains) and less effective soil organisms. However, in studies
with soybean we have shown that the inoculant strains are quite competitive
for nodulation sites at the crown of the plant but are immobile in soil and
so produce very few nodules on lateral roots. These studies are being
repeated for Phaseolus in Ecuador. From preliminary data it appears that
N2 fixation supplies from 37-41 percent of overall plant nitrogen needs, but
that indigenous strains do limit inoculant strain response. A number of bean
rhizobia have been selected for enhanced competitive performance, speed in
nodulation and efficiency in N2 fixation. We must also enhance the duration
of crown nodules and develop methodologies for greater lateral root
nodulation.
4. Acid-pH tolerance in Rhizobium: In studies initiated in 1983, the PI had
sought bean cultivars and rhizobia capable of persistence and nodulation in
acid soils. As part of this study, six uniquely acid-tolerant bean rhizobia
were identified. All were markedly different to previously studied bean
strains. Studies to clone the pH tolerance genes from these organisms are
underway; we have also induced pH "shock" proteins and are studying
host-strain interaction at acid pH.
As with the other CRSP programs, collaboration and training are integral parts of
the project. Students from Colombia, Ecuador, Uganda and the U.S. have initiated
studies in the PI's laboratory; a post doctoral fellow has been stationed at
INIAP where he will help in the selection and in-country training of recent
graduates. Contacts have been established with CIAT personnel and with the
Tanzania project.
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Question and Answer period: ECUADOR
Q: Do acid-tolerant bean rhizobia give better responses to inoculation under
acid conditions in the field?
A: In two studies where low pH was the major factor limiting nodulation and N2
fixation, use of acid-tolerant strains permitted good yield response to
inoculation. We would recommend use of such strains under acid conditions in
the field.
Q: Is nitrogen fixation quantitatively inherited?
A: We assume that this trait is quantitatively inherited, however, Bliss has
shown that significant gains in nitrogen fixation can be obtained without
recourse to recurrent selection programs.
Q: Is competition from native soil strains likely to be important in Ecuador?
A: We have only preliminary results but they suggest that most soils have
indigenous bean rhizobia, and that these can limit response to inoculation.
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GUATEMALA/CORNELL UNIVERSITY/ICTA
Donald H. Wallace and Raphael Rodriguez
Physiological, Genetic and Agronomic Aspects of Bean Adaptation and Yield
Presenters: D. H. Wallace and Raphael Rodriguez
For each different geographical site, yield system analysis of ongoing yield
trials can raise efficiency of improving genetic adaptation and yield potential.
This can maximize regional and worldwide yields. Within each ongoing yield trial,
yield system analysis identifies the genotypes having superiority for each of the
major physiological components of yield. These superior genotypes will represent
the alternative pathways to yield discussed in the next three paragraphs. Inter-
crossing these superior genotypes selectively places the large, site-adapted
genetic variability needed for yield improvement into the also needed common gene
pool.
The proposed increased breeding efficiency is based on evidence that the three
major components (total biomass accumulation, harvest index, and the time a
cultivar requires to develop to harvest maturity) are simultaneously controlled
by partitioning of the available photosynthate. In turn, the partitioning is
controlled by maturity genes.
One pathway to yield is partitioning the larger proportion of the photosynthate
to existing organs of yield (flower buds, pods and seeds). This reduces the time
to harvest maturity, because these organs grow rapidly and therefore develop
(flower and mature) in a short time. The early maturity is reinforced through
the correlated restriction of continued vegetative growth, which will be supported
only by the small proportion of the photosynthate not partitioned to the
re-productive organs. The high daily rate of yield accumulation combined with
the also correlated high harvest index will give high yield for short growing
seasons. Earlier maturity and its correlated higher yield per day will maximize
yield per growing season for sites with long growing seasons, if there can be
change from one to two successive plantings. Bean farmers of highland Guatemala
are beginning to do this.
Alternatively, high yield can come from the increased biomass accumulation that
results from partitioning predominantly to continued vegetative growth. This
will increase the node number (potential sites for yield) and leaf area (photo-
synthetic capacity), in correlation with the longer growth duration. The lower
rate of yield accumulation will be compensated by the longer growth duration, if
the growing season is long enough.
For both short and long growing seasons, yields will be yet higher if the genotype
provides a high daily rate of biomass accumulation.
High yield is selected for at all geographical sites. Development to harvest
maturity varies between 80 and 270 days for bean cultivars at different geograph-
ical sites. We have shown that partitioning and the consequent rate of
development and correlated time to maturity can be strongly controlled by a
single photoperiod gene. A cultivar may have a (control 1) genotype which is
insensitive or moderately or highly responsive to (control 2) daylength. Progres-
sively more sensitive genotypes will cause progressively larger delays of
flowering and maturity as will progressively longer daylengths. With synergism
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that is positively correlated with the combined effected by the genotype plus the
daylength, a (control 3) higher mean temperature at the site will additionally
enhance the level of activity of the photoperiod gene(s). This will further
reduce the partitioning to the yield organs and further delay flowering and
maturity. Supporting this, yield system analysis across 52 geographically
dispersed yield trials indicated, with 0.0001 statistical probability of error,
that harvest index (partitioning) is negatively correlated with days to maturity.
The higher temperature also (and simultaneously) accelerated (control 4) the rate
of node development, i.e. decreased the days needed to develop a node and thereby
tended to cause earlier flowering. This effect by temperature is acceleration of
the rate of vegetative growth and development. The accelerated rate of node
production due to higher temperature will tend to reduce the days to flowering
and maturity. Therefore, the extent to which a higher mean temperature will
lengthen or, alternatively, will shorten the time required to develop to
flowering depends on the larger of temperature's simultaneous but opposite
effects: a) through delayed reproductive development vs. b) through more rapid
vegetative development. For each combination of genotype and daylength, there is
an optimum temperature, at which the opposite effects exactly cancel. This
optimum temperature results in the most rapid reproductive development, i.e. the
fewest days to flowering. At temperatures below this optimum, changes of days to
flowering by temperature are largest through vegetative development. The changes
are largest through reproductive development at temperatures above the optimum
for flowering. Other classes of maturity genes also interact. These genes alter
partitioning and days to flowering and maturity by determining (control 5) the
number of nodes on the plant shoots, (control 6) the minimal node to flowering,
and (control 7), specific gene(s) may exist which give major control over the
rate of node development.
As predicted by the above, biological causes of correlations among biomass,
partitioning and maturity, selection in the past for only yield has raised yield
primarily by causing a larger proportion of the biomass to be partitioned to the
yield. This occurs because as few as 10 to 12 maturity genes, some with multiple
alleles, control the time to maturity (cultivar adaptation). These few maturity
genes join with the thousands of other genes in controlling total biomass
accumulation. Control by few genes gives maturity much higher heritability than
is given to biomass accumulation through its control by many genes. Selection
for only harvest index (partitioning) will lead to early maturity accompanied by
correlated tendency toward lower yield. This can be corrected by simultaneous
selection for later maturity and/or higher aerial biomass. Selection for only
larger biomass will lead to late maturity plus correlated reduction of harvest
index and yield but can be compensated by simultaneous selection for earliness
and/or rate of biomass accumulation. The conclusion is that efficient improvement
of genetic potential for yield requires simultaneous selection pressure on all
three of yield's major components: the rate of biomass accumulation, the
partitioning rate and the time required to develop to harvest maturity.
For each geographical site, the complex, multiple-trait, maturity genotype
interacts with the daylength and the temperature to establish the "adapted" range
of the continuum of partitioning predominantly to continued vegetative growth vs.
partitioning predominantly to continued reproductive growth. This partitioning
controls the rate of yield accumulation vs. the rate of total biomass accumulation
and their combined effects on adaptation, maturity and yield. These effects on
yield interact with a final influence by the actualized duration of the growing
season. For plantings at a repeated time of year, daylength is fixed and
therefore tends to always cause the same effect on both yield and the length of
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the growing season. Nevertheless, every site has a range of maturity that will
give acceptable yield. The narrow to wide range depends on the variability of
the mean temperature and/or of moisture availability within the growing season
and upon the irregularity of the cessation(s) of plant growth which these
environmental variabilities cause.
Temperate sites have wide variations of temperature, moisture and growing season
duration. This causes the earlier cultivars of the "adapted" range to give the
highest yields for some years, while the latest "adapted" cultivars yield most
for other years. Tropical sites have more repeatable mean temperature. With
irrigation, therefore, they have higher potential for effective selection for
yield during the early segregating generations after a cross.
A major constraint to breeding for higher yield has been inability to quantify
genotype x environment interaction effects on yield. The largest physiological
genetic causes of this interaction are described above. Quantification of this
genotype x environment interaction, determining the yield potential of cultivars,
and establishing true relationships of yield with its physiological-genetic
components all require yield trials of multiple genotypes grown across multiple
site-seasons. A new statistical procedure called AMMI analysis quantifies the
genotype x environment interaction effect caused by each genotype and by each
environment. The procedure uses the measurement of the genotype- and
environment-caused positive or negative deviation around the grand mean of all
the data. The analyzed trait may be yield or a physiological component of
yield. The larger the number of genotypes tested, and especially the number of
environments, the more accurately the mean of the genotype and the deviations
from the grand mean will be measured.
Yield system analysis of each yield trial identifies the physiological genetic
components of yield and demonstrates that the genotypes are adapted to the
site-season's environment. Yield system analysis across multiple site-seasons
combined with AMMI analysis will provide advancement, by each yield trial, of
understanding of the complex yield system. It will quantify the genotype x
environment interaction. It will also support mathematical modeling of plant
development and yield and its application to breeding and crop production
practices. Collaborative research on yield will be facilitated among agronomists,
horticulturalists, breeders, geneticists, physiologists and biotechnologists.
The theoretical basis is described above. Its application via yield system
analysis has been described. The theoretical basis, yield system analysis and
AMMI analysis can stimulate interdisciplinary and regional collaboration on yield
research of beans and most other crops.
The delay in days to flowering is caused by the sensitive allele of a single
photoperiod gene. This gene largely controls the difference in days to flowering
and adaptation between two Guatemalan cultivars. Photoperiod gene activity was
indicated by late flowering under 16 hour daylength in a greenhouse in New York,
compared against earlier flowering for this genotype in 12 hour daylength. Also
shown, the 290C temperature of a Guatemalan lowland site delayed flowering by
this photoperiod sensitive genotype. AMMI analysis showed that the photoperiod
gene activity caused the mean days to flowering to increase in correlation with
increasingly positive deviation from the grand mean days to flowering. The 290C
of the Guatemalan lowland site caused positive deviation like the long daylength.
The 19C of the Guatemalan highland site caused negative deviation like the short
daylength.
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Control of early vs. late flowering by other classes of maturity genes does not
cause correlation between the progeny mean and the deviation from the grand
mean. Both the early and the late genotype expressed the full range of deviation
around the grand mean. Another difference was that the 16 hour daylength did not
cause positive deviation above the grand mean days to flowering, but caused
negative deviation like that for the 19 temperature.
During the 1990 and 1991 growing seasons, the F8 progenies that are homozygous
for the different classes of maturity genes will be grown at low, intermediate
and high temperature Guatemalan sites. The data will be subjected to yield
analysis followed by AMMI analysis. This will reveal the effect of mean
temperature on the rates and durations of aerial biomass accumulation and its
partitioning and the correlated developmental times to flowering and maturity.
Research is underway to find molecular markers on the same chromosomes as the
different maturity genes. This will facilitate selection for maturity genotype
using seedlings, rather than having to grow the plants to flowering and maturity.
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Question and Answer period: GUATEMALA
Q: Sampling aerial biomass may be too expensive for our breeding program. How
much do we sacrifice by not measuring this trait?
A: You cannot estimate total biomass, biomass/day or harvest index without
measuring aerial biomass. There may be a line which produces a large amount
of biomass but has poor yield. We need to work with physiologists to better
understand how high biological yield can be converted to economic yield.
Q: Did you state that "growth habit" was controlled by maturity genes?
A: Yes, in a sense. The 10-15 genes that control harvest index have a great
influence on the economic yield and adaptation of a genotype. Selection only
for harvest index, however, may result in earlier maturity and lower yield
potential. High harvest index lines are often more sensitive to stress
environments.
Q: How much can be achieved by selecting for enhanced biomass/day?
A: The yield system analysis (YSA) is new. Therefore, the value of this
approach has not been determined.
Q: Can YSA method be used for cowpeas?
A: Yes, the approach should be useful for all grain legumes.
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HONDURAS/UNIVERSITY OF PUERTO RICO/EAP
James S. Beaver and Juan Carlos Rosas
Improvement of Bean Production in Honduras Through
Breeding for Multiple Disease Resistance
Presenters: James S. Beaver and Juan Carlos Rosas
Several diseases limit the productivity of beans in Honduras. Results from field
trials conducted at the Escuela Agricola Panamericana (EAP) found both rust and
anthracnose to significantly reduce the yield of susceptible genotypes. Many of
the small red varieties currently planted in Honduras are also susceptible to bean
common mosaic virus (BCMV). During the "primera" growing season common blight
can reduce both the yield and quality of beans. Since seed from the "primera"
season is usually used to plant the "segunda" crop, seed transmission of common
blight often occurs. During the 1989 growing season bean golden mosaic virus
(BGMV) infected several thousand hectares of beans in Honduras. Consequently,
farmers need bean varieties with enhanced levels of disease resistance in order
to insure a greater, more predictable level of production in the wide range of
environmental conditions in which beans are grown in Honduras. The principal
objective of the project is to identify and incorporate genes for disease resis-
tance into bean genotypes having seed types that are acceptable to the Honduran
consumer. Due to the great amount of variability in virulence among indigenous
bean rust isolates, Honduras provides an ideal environment for studying the life
cycle and epidemiology of this important disease. The project also strives to
strengthen the bean research programs of the EAP and the Ministry of Natural
Resources (MNR).
Small red breeding lines with resistance to one or more of the most important
diseases have been developed or identified. Thus, the first step toward the
development of small red bean varieties with multiple disease resistance has been
accomplished. Small red lines having both the "I" and "bc3" genes for resistance
to BCMV have been developed by the project. These breeding lines are resistant
to all known strains of BCMV. All available sources specific of resistance to
bean rust have proven to be susceptible to the races present in Honduras.
However, results from field trials have found bean genotypes having dense
pubescence on the abaxial surface of the leaves to have less rust infection than
glabrous genotypes. Small red bean lines having dense leaf pubescence have been
developed by the project using Dominican red mottled genotypes as the source of
the dense pubescence. Anthracnose resistance has been identified in the recently
released small red variety "Cathrachita" and in breeding lines HND30-40 and
EAP12-88.
Moderate levels of resistance to common blight are found in breeding lines
EAP10-88 and UPR64-1. Small red lines have also been selected from populations
derived from crosses with BAC6. These lines will be screened for reduced seed
transmission of Xanthomonas campestris pv. phaseoli. Small red lines DOR364 and
DOR391 have proven to be moderately resistant to BGMV in Honduras. These lines
have been used as parents in the breeding program. In addition, seed of DOR364
has been increased at the EAP in the event that the incidence of BGMV continues
to increase. The performance of promising small red breeding lines produced by
the project are tested on farms in Honduras by the MNR. Elite small red lines
developed by the project are also included as entries in the CIAT coordinated
VIDAC nursery which is conducted in several Central American countries.
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Bean germplasm continues to be screened for additional sources of resistance and
for other useful agronomic traits. Honduran landrace varieties have proven to be
a very useful source of early maturity for indeterminate beans. In Honduras,
early maturity helps to avoid disease, drought and low market prices. Results
from inheritance studies indicate that selection for earlier maturity would be
most effective in replicated, advanced generation nurseries. These studies also
produced breeding lines with longer reproductive periods by combining earlier
flowering with later harvest maturity. Field experiments are currently being
conducted to determine the relationship between the length of the reproductive
period and yield. Screening for common blight resistance during the summer months
has also resulted in the identification of small red breeding lines that yield
well under the hot and humid conditions that prevail during that growing season.
Greater levels of heat tolerance would permit more bean production in the lower
altitude valleys in Honduras and other Central American countries where agricul-
ture would be more sustainable. Studies are presently underway to estimate the
heritability of this trait.
A method for extraction of high molecular weight genomic DNA from rust spores has
been developed. The extracted DNA was used for Restriction Fragment Length
Polymorphism (RFLP) comparisons among seven single pustule isolates selected on
the basis of virulence. These isolates represent rust populations from the U.S.,
Honduras and the Dominican Republic. Differences in hybridization bands among
the different isolates have been observed. These preliminary results indicate
that this technique may offer a unique method for studying the relationship among
rust races and for facilitating the identification of virulence patterns.
Training is provided by both the U.S. and HC institutions. At present, the
project provides support for an agronomist from the MNR to pursue an M.S. degree
in plant breeding and genetics at the University of Puerto Rico. The University
of Nebraska provides training in research techniques for working with bean rust.
At the EAP, "Ing. Agr6nomo" thesis research projects related to bean breeding and
pathology are supported by the project. Informal training in bean research
techniques is also provided to the MNR agronomist stationed at the EAP.
During the next extension period the project will concentrate on combining the
different disease resistances that now exist in small red breeding lines. Partic-
ular emphasis will be placed on seed-borne diseases such as BCMV, common blight
and anthracnose since most farmers in Honduras continue to grow their own seed.
Screening for BCMV resistance will be conducted in the screenhouse in Puerto Rico
using the appropriate strains of BCMV. Breeding lines will be screened for field
reaction to common blight, rust, anthracnose and BGMV in nurseries planted during
seasons when particular diseases are prevalent. Since many of the crosses will
be between adapted small red genotypes, the likelihood of releasing small red
varieties with multiple disease resistance should be good. However, it will be
necessary to remain vigilant of interactions which may result when different
sources of resistance are combined. Germplasm will be screened for resistance to
BGMV and common blight since only moderate levels of resistance for these diseases
are present in small red beans. The project will continue to collaborate with
CIAT in conducting nurseries for rust, common blight and BGMV. Evaluation of the
EAP bean germplasm collection will be supported by the Bean /Cowpea CRSP project
and the International Board of Plant Genetic Resources (IBPGR). Researchers at
the EAP have gained experience using the congruity backcross method to transfer
drought tolerance from tepary beans to common beans. A similar approach will be
used to transfer high levels of resistance to common blight and heat tolerance
from tepary beans that were selected from field trials that were conducted during
the summer in Puerto Rico.
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Question and Answer period: HONDURAS
Q: Why not use determinate growth habit if you wish to develop early maturity
beans?
A: (1) Farmers in Honduras often grow beans in association with corn.
Indeterminate habit is more appropriate for this cropping system. (2) Very
good sources of earliness are available in indeterminate "Criollo" lines.
(3) Research has found determinate growth habit more sensitive to stress and
less stable in yield than indeterminate growth habit.
Q: Are the common blight strains in Honduras and Puerto Rico the same?
A: Probably not. Initial screening was conducted in Puerto Rico to select lines
with moderate levels of resistance. However, the lines are sent to Honduras
as soon as possible in order to expose them to the indigenous strains of
Xanthomonas campestris.
Q: Could you provide more details concerning the RFLPs of the single spore
isolates of rust?
A: The research is in the initial stages. High molecular weight DNA has been
isolated from single pustule isolates of rust. We will attempt to relate
variability in RFLPs with virulence patterns.
Q: Could the project use more help with white fly research?
A: Yes, there are entomologists at UPR with experience with white fly who have
provided assistance to us. A better understanding of the white fly and
natural enemies is needed to develop more effective management techniques.
Incidence of bean golden mosaic was reduced in the DR by a two-month fallow
period of host crops. The reduction was attributed to a decrease in the
white fly populations.
Q: In your heterogeneous mixtures, how can you insure that the mixtures are
genetically diverse? Any evidence of transgressive segregation?
A: We plan to maintain records of pedigrees to insure that different parents are
used. The only transgressive segregation observed has been with reproductive
period (RP) where the RP of the progeny have exceeded the RP of the parents.
Q: What do farmers do to control diseases?
A: The farmers plant early varieties to avoid disease. There is some evidence
from Africa that intercropping with corn helps to reduce the incidence of
foliar fungal pathogens such as rust and angular leaf spot. Many of the
pathogens in Honduras are seed-borne. If we could improve the resistance to
the seed-borne pathogens, the incidence of disease could be reduced.
Q: What is the status of your work in Jamaica?
A: Research is supported by Jamaican Agricultural Research Foundation. The goal
of the project is to improve disease resistance and biological nitrogen
fixation of Jamaican red beans. The first year of research has been
initiated. We look forward to a more formal relationship with the
Bean/Cowpea CRSP.
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INCAP/WASHINGTON STATE UNIVERSITY/INCAP
Barry G. Swanson and Ricardo Bressani
Improved Biological Utilization and Acceptability of Dry Beans
Presenters: George Hosfield, Ricardo Bressani and Barry Swanson
Genetic Improvement:
The genetic control of tannin and protein content, cookability and tactile and
visual culinary quality traits of dry beans is quantitative in nature, implying
that small effects of several genes are involved in inheritance and that the
environment strongly influences the food quality of dry bean cultivars and
breeding lines. The predominant genetic cause of variability for the nutritional
and quality traits in breeding populations was the existence of genes with partial
to completely dominant expression acting in an additive fashion, i.e., responding
linearly to an increase in the number of active genes affecting trait expression.
Some genetic strains of beans lost up to 3 percent reserve protein during prepara-
tion for consumption while others showed no protein loss during soaking and
cooking. Variation among genotypes for protein retention is of particular
interest because it indicates that consideration other than the original protein
content is important when beans are used in human diets. Recurrent selection
which seeks to concentrate favorable alleles in a population may effectively
improve the food quality of beans through breeding.
"Calima" beans, when cooked as a pure line, reduced firewood needs of Rwandan
small farmholders by 16 percent compared to the fuelwood required to cook
traditional mixtures. Extrapolation of the bean cooking results indicated that
the adoption of fast-cooking bean cultivars in diets of 50 percent of Rwandans
will save 76,000 tons of wood annually. Although significant firewood and labor
savings accrued with the use of fast-cooking beans, Rwandan women preferred
mixing the fast-cooking genotypes with traditional types that are slower cooking
thus negating some of the benefit. The use of the haybasket cooker reduced
firewood needed for cooking beans by 40 percent compared to the traditional open
fire cooking method. Projected fuelwood savings using the haybasket at a 50
percent adoption rate was 173.3 thousand tons. A 2 percent increase in family
income may also occur due to labor savings with the haybasket. Current annual
household income in Rwanda is 55,000 Rwandan francs or $550.
Nutritional Quality:
For many people in developing countries, beans constitute the most important
complementary source of protein to maize and other cereal grains. The nutritional
quality of beans is of significant importance. The main constraints limiting
consumption and nutritional quality of beans are acceptability characteristics,
cooking time being perhaps the most important; protein quality, since protein
digestibility is relatively low compared to protein from animal products; and
antiphysiological factors including tannins, lectins and enzyme inhibitors that
may not be eliminated by cooking. These factors limit bean consumption by
people, consumption which could be increased if common beans were used in more
acceptable and convenient food products. The reasons for the low protein
digestibility are being investigated; seed coat, dietary fiber and tannins
decrease protein digestibility. Reduced protein digestibility is extended to
complementary bean cereal diets as well. Bean seed coats contribute great
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concentrations of dietary fiber and tannins. During cooking or processing,
dietary fiber binds irreversibly 9-12 percent protein unavailable to the
consumer. Tannins may bind dry bean proteins or inhibit gastric proteolytic
enzymes. A number of acceptable food products have been developed using beans
including high protein dried powder soups, chili beans with texturized soy
protein and cereal-bean-vegetable mixtures with improved nutritional value.
Protein Digestibility:
The resistance of native legume proteins to proteolysis by mammalian digestive
enzymes contributes to the poor nutritive value of dry bean proteins. Attention
is focused on phaseolin, the major storage protein of dry beans (Phaseolus
vulgaris). While heated phaseolin is susceptible to proteolysis, native phaseolin
has been shown to be largely resistant to hydrolysis of trypsin, chymotrypsin and
pepsin. Theories proposed for resistance to proteolysis include compact
structure, stability and steric hindrance imparted by protein glycosylation.
There are a number of factors which suggest that in vitro enzymatic hydrolysis of
legume proteins may not be expected to correspond to in vivo hydrolysis. The
binding of starch with protein is an important consideration for in vitro assays
but is unlikely to be important for in vivo assays. Although supplementation
with sulfur-amino acids improves legume protein quality, limiting methionine and
cysteine concentrations will not normally be a problem since legumes are often
utilized in conjunction with animal or cereal proteins.
The deficiency of sulfur amino acids alone is not the only factor which limits
the nutritive value of cooked legumes. The interaction of proteins and
procyanidins increases polymerization of procyanidins occurring during soaking
and heating of dry beans. As procyanidin polymerization increases, the
interaction of proteins and procyanidins becomes irreversible and results in
reduced protein quality. Recent evidence suggests procyanidin interaction with
proteins may be hindered considerably by polysaccharides present in storage
tissues.
-37-
Question and Answer period: INCAP
Q: Do white beans exhibit greater digestibility than colored beans?
A: White beans contain few or no procyanidins, yet the digestibility is not
always better than the digestibility of colored beans. The digestibility of
proteins in white beans is poor.
Q: How was gas volume related to bean digestibility?
A: Bean flour was used as the substrate. Pig feces isolates were used as the
inoculum, and volumes were assessed by water replacement.
Q: Do lectins in beans play a role in nutritional quality?
A: Comprehensive studies have isolated and characterized lectins in beans.
Currently, none of the isolated lectins are heat stable, so lectins are
destroyed by cooking. Lectins are peptides containing quality amino acids,
so denatured lectins add protein quality to beans.
Q: How does the INCAP project interface genetics and food technology?
A: George Hosfield is proposing research with single genes in model systems to
characterize the contribution to food quality. It is essential to conduct
food quality assays with "standard" and "known" cultivars as lines of beans.
Beans with known histories are necessary to conduct storage, processing, and
food preparation studies of consequence and reproducibility.
The INCAP project has led the way for collaboration utilizing "standard"
cultivars in breeding studies and related food quality studies. The project
has published numerous methods of value for the assessment of bean quality
and acceptability. The project is completing a manual that will describe
analytical methods to assess bean constituents, quality and acceptability.
The INCAP team believes that the food science component of the Bean/Cowpea
CRSP has set an example for the integration of breeding and biochemistry as
well as using other interdisciplinary and collaborative studies.
-38-
MALAWI/MICHIGAN STATE UNIVERSITY/BUNDA COLLEGE
M. Wayne Adams (Acting PI) and A. B. C. Mkandawire
Biological and Socio-Cultural Parameters of Bean Improvement and Host/Pathogen
Co-Adaptation in Malawi, a Secondary Center of Diversity
Presenters: Anne Ferguson and A. B. C. Mkandawire
Project Objectives--The primary objective of this second phase of the genetic
diversity project is to assist the Malawian National Bean Program in developing
improved bean varieties (and/or mixtures) and production technology. The
secondary objective is to study host-pathogen specialization with respect to two
important diseases: anthracnose (ANTH) caused by Colletotrichum lindemuthianum
and angular leaf spot (ALS) caused by Phaeoisariopsis griseola. Both objectives
involve biological and socio-cultural research.
Ongoing Research:
Socio-cultural surveys of bean production practices and preferences were carried
out in the Northern, Central and Southern Regions of Malawi. These surveys
gathered information on regional preferences in seed types and data on preferred
varieties and cultural practices among different groups of smallholders. The
survey results are used in the National Bean Improvement Program. They provide a
basis on which to make decisions regarding seed types and traits selected for
improvement efforts and allow crop improvement efforts to be directed toward the
needs of specific vulnerable groups.
One outgrowth of the collaboration between biological and social scientists has
been the development of a breeding strategy suitable for use in areas of the
world such as Malawi where farmers grow beans as intravarietal mixtures. Termed
component breeding, this strategy is being employed in the Malawian National Bean
Improvement Program and considered for use in other bean programs in eastern and
southern Africa.
In conjunction with the Adaptive Research Unit in the Ministry of Agriculture,
efforts are currently underway in Malawi to develop a system of bean varietal
testing and release that involves farmers in all stages of the research process.
Efforts are also being made to develop a system of seed multiplication for use in
Malawi.
Germplasm screening: Disease resistance--entries from the Malawian national
germplasm collection comprising preferred seed types and lines resistant to halo
blight (Pseudomonas syringae pv. phaseolicola) are evaluated for resistance to
ALS and ANTH under natural infection in field nurseries. Twenty-two indigenous
accessions were challenged by two virulent isolates of ALS in controlled
inoculation tests.
Drought resistance--entries in irrigated, rain-fed and imposed drought tests, the
latter timed at flowering or at seed-fill, included released varieties and
breeding lines from South America, North America, South Africa and Malawi. Tests
are conducted during the dry and rainy seasons and at the end of the rainy season
to exploit diminishing residual moisture. Root and shoot biomass and seed yield
and its components are measured.
-39-
Insect resistance--cultivars, local accessions and breeding lines are evaluated
at Bunda College under natural infestations in the field. The most prevalent
pests are the bean fly (Ophiomyia spp.), a chrysomelid and the bean beetle
(Ootheca spp.). A total of 23 lines were screened for reaction to the bean fly,
17 of which were CIAT accessions reported to be resistant or tolerant, and six
local agronomically superior selections. Early planted beans had lower adult
populations. CIAT entries were most attractive to adult insects, but larval and
pupal counts were relatively low. Malawi lines were generally intermediate in
terms of numbers of adult flies.
Variety performance tests--the tests for grain yield were conducted at five sites
throughout Malawi during the rainy period, and included eleven entries comprised
of introductions, landrace selections, hybrid materials and one check variety,
Nasaka.
Evaluation of intercropping systems--planting pattern tests have been carried out
with both bush and climbing types. Tests were conducted at four sites with bean
varieties and maize types grown singly and in association. Yield and yield
components data were recorded and main and interaction effects determined.
Host/pathogen co-evolution studies--plant pathogens were sampled to determine
patterns of variability and racial identity. Samples of ALS were collected from
plant tissue of beans growing in the Southern Region during the rainy season. A
total of 130 strains were isolated in the plant pathology laboratory at Bunda
College as single spores and subsequently multiplied in culture. These 130
cultures have now been received at MSU for isozyme analysis. The cultures
retained at Bunda have been race-typed using a set of ten differentials that were
multiplied under irrigation at Bunda in 1989. Seeds of plants sampled for ALS
were collected to establish gene-pool identity.
Isozyme and dwarf-lethal studies--isozyme analysis of 130 ALS isolates are being
carried out on hyphal extracts of colonies maintained on artificial media in the
laboratory at Michigan State. The isozymes are electrophoresed on horizontal
starch gels. The resulting zymo-patterns will be correlated with the gene pool
identity of the host plant from which each ALS isolate was taken to test the
hypothesis of co-evolution. At Bunda, the virulence tests on bean gene-pool
differentials will have provided data with which to support or refute the
hypothesis.
In addition, a total of 675 bean accessions from the areas of Lilongwe and Dedza
(Malawi) are being crossed with two cultivars of known dwarf-lethal genotype,
Sierra pinto (DL1) and Montcalm kidney (DL2) to determine the distribution of
dwarf-lethal genes in the Malawian bean gene pools.
Mitochondrial DNA RFLP analysis--mt DNA was isolated from 10 to 21 day old
seedlings of 23 bean genotypes (20 from Malawi landraces, differing in "genetic
distance," seed characteristics, isozyme patterns and in phaseolin patterns and
three representing standard Andean and Meso-American gene-pools). The mt DNAs
were digested with eight restriction endonucleoses and the fragments separated by
horizontal electrophoresis in agarase gels of varying percentages. After photo-
graphing, the restriction fragments were transferred to nylon hybridization
membranes where, after baking or UV crosslinking, the membranes were consecutively
hybridized to three or four different probes comprising random DNA sequences of
the bean mt genome.
-40-
Significant Results:
Training--Five Malawians have received graduate degrees under CRSP auspices and
have returned to Bunda College, thus placing Malawi in a strong position to carry
out research on beans--the major source of protein for the population. U.S.
students have also received training in international agricultural research,
strengthening the U.S.'s ability to conduct research in this area.
Understanding of the complex array of socio-cultural and biological factors which
underpin genetic diversity in Malawian bean landraces--Studies of the social and
biological social factors accounting for genetic diversity in Malawian beans were
a major thrust of the first eight years of project research. Numerous presenta-
tions and publications have resulted from these studies and this information is
being used in the current bean improvement program as a basis for selection of
varieties for improvement purposes.
Isozyme studies in Malawian bean landraces--Studies involving 375 landrace
components revealed two principal patterns of variability and several mixed
patterns. The two main patterns were perfectly correlated with seed size and
phaseolin type indicating these alternative allelic state patterns were gene-pool
specific. This in itself was a surprising outcome for several reasons. The
mixed patterns are the result of gene pool recombination, another surprise in
view of the known hybrid sub- or in- viability of inter-gene pool crosses.
Diversity in Malawian beans using mitochondrial DNA cut with restriction
endonucleases--This work has shown that the mt genomes of Andean and Central
American gene pools are distinct from each other. Two large-seeded U.S.
cultivars, however, do not follow this pattern, being comprised of mt genomes
that show predominantly Central American RFLP characteristics.
Germplasm collection--Bean landraces have been collected from all major bean
growing regions in Malawi. These landrace accessions are maintained at Bunda
College (with duplicates at CIAT and Pullman, Washington) and are being grown out
and characterized. Representing a wide range of preferred seed types, these
landraces serve as a basis for the Bean Program's crop improvement efforts.
Varietal releases--The Malawian National Bean Program is in the final stages of
testing four new bean varieties (three dry bean cultivars and one snap bean
cultivar) for release purposes. These varieties are being tested at research
sites throughout the country.
-41-
Question and Answer period: MALAWI
The seed multiplication and distribution issue, as in Tanzania, was raised.
Companies will not make money on beans since farmers (small landholders) keep
seed for a number of years. The artisan system is being advocated by CIAT and
may be useful for CRSP projects.
A discussion of component breeding problems indicated the difficulty for the
government in seed multiplication, testing and release of numerous lines. Thus,
if components with genetic diversity are created as a strategy that by bulking
earlier heterozygous lines (say at F5) some diversity can be created.
Outcrossing rates of 1 percent are common in Malawi--but if lines with higher
outcrossing rates can be found, it was suggested that this could diversify the
breeding lines. Thus, landrace cultivars with improved characteristics could be
released. Further discussion on component selection raised the issue of whether
landrace evolution was actually occurring. Since socio-cultural studies have
highlighted the selection process made by the farmer, evolution (or co-evolution
of host [pathogen] is not the only processing going on).
A question was raised on whether bush or climbing types were targeted in the
project. It was stated that both types will be considered in the CRSP as it will
be for the CIAT breeding program.
Farmer priorities did not have diseases/pests ranked high and this did not seem
to match project priorities. The explanation to this is that farmer perceptions
of yield (highest rank) have pest and disease impact mixed with total yield. A
study should be done on evaluating farmer perception of disease/pest problems.
-42-
MEXICO/MICHIGAN STATE UNIVERSITY/INIFAP
Dale Harpstead and Jorge Acosta Gallegos
Improving Resistance to Environmental Stress in Beans Through Genetic
Selection for Carbohydrate Partitioning
Presenters: Dale Harpstead, Eunice Foster and Jorge Acosta Gallegos
This project can be characterized as a coordinated, multifaceted effort which
includes both basic and applied research. It has been designed to identify new
genetic resources for drought resistance, evaluate physiological plant responses
to moisture stress and to incorporate favorable plant responses into commercially
acceptable varieties for the central highlands of Mexico. This is being accom-
plished through close coordination between field and laboratory activities in
Mexico and Michigan.
Drought resistance in edible dry beans, as in other fast growing annual crops, is
the product of favorable plant growth patterns, compensatory plant physiological
responses, and morphological features which maximize water use efficiency. In
most cases, these are directly or indirectly under genetic control. Progress has
been made in the identification of superior drought resistant genotypes through
extensive regional testing, utilization of induced moisture stress and the evalu-
ation of relative growth rates. Rigorous elimination of drought susceptible
genotypes coupled with aggressive genetic recombinations among selected genotypes
has resulted in progress toward more acceptable varieties for commercial
production albeit at a very slow rate.
Recurrent selection strategies result in continuing evaluation, plant selection,
recombination and retesting procedures. In 1988 more than 2300 individual plants
were selected for further testing. Seed of these was increased in a winter
nursery in 1989 to be used in field plot tests in 1990. Special field nursery
environments are maintained for selection against stresses caused by root rots
and various foliar disease organisms.
To efficiently direct plant breeding approaches toward higher levels of drought
resistance, it is necessary to have the capacity to recognize essential plant
response characteristics independent of associated confounding of plant growth
factors and/or environmental interactions. To achieve these goals, additional
research has been directed toward basic plant physiology, storage and remobili-
zation of photosynthate, and molecular marker patterns which could be used to
describe the genetic complement of the desired plant types. Three broad
categories of drought response in plants are recognized: escape, avoidance and
tolerance. In an escape strategy, the life cycle of the plant is regulated to
produce seed before the water supply is exhausted. Rapid growing, early maturing
genotypes are the most common example of this strategy.
For bean production in the semiarid highlands of central Mexico, a drought-
avoidance strategy is the principal plant breeding goal. An attempt is being
made to identify a series of physiologic plant responses which operate indepen-
dently or in concert to prevent or reduce the damaging effects of moisture
stress. These include the maximizing of water uptake by deep and extensive root
systems; minimizing water losses through stomatal control, leaf movements and
leaf shedding; and cell sap osmotic adjustments which enhance short-term survival
under conditions of water stress.
-43-
To identify more favorable drought avoidance responses additional emphasis is
being placed on the utilization of selection indices developed in moisture-
stressed and irrigated field plot environments which incorporate data from total
biomass, root biomass, seed yield, maturity, N2 fixation and growth habit
measurements.
Drought tolerance in classical terms is associated with xerophytic vegetation.
Nitrogen is essential to plant growth and regrowth processes and has a high
probability of involvement in plant adaptation to stress. Thus, extensive
studies of nitrogen storage and remobilization have been made. In these studies,
nitrogen becomes an invaluable tool inasmuch as it is vital and can be supplied
to the plant as the stable isotope 15N-urea which can be identified after it has
been translocated and incorporated into various growth and storage organs of
plants grown in controlled moisture environments.
Work is in progress to identify biochemical marker loci that can be associated
with quantitative trait loci (QTLs) in drought resistant and drought susceptible
bean genotypes. Isozyme marker characteristics of more than 25 INIAP drought-
resistant bean genotypes and 15 drought-susceptible genotypes previously
classified in the field in Mexico have been cataloged by starch gel electro-
phoresis. Distinct polymorphisms have been recorded for 10 of the 23 isozymes
investigated. These are being further analyzed for environmental stability and
heritability.
This project must consider more than grain yield per se. The market demands
distinct classes of beans based on color, grain size, culinary characteristics,
cooking time, etc. to name only a few. In addition, the farmers in Mexico are
dependent upon bean forage for animal feed and require high levels of disease and
insect resistance to protect the crop from other environmental hazards.
Future research plans call for: (1) the increased testing of genotypes identi-
fied in the recurrent selection programs, (2) increased use of selection indices,
(3) evaluation of market and use acceptance of selected genotypes, (4) identi-
fication of plant chemical/physiological responses associated with drought
resistance, (5) utilization of labeled nitrogen and carbon to monitor plant
growth/regrowth characteristics and (6) the use of DNA analyses to complement
isozyme markers to monitor drought response in selected genotypes.
-44-
Question and Answer period: MEXICO
Q: How will seed of improved varieties be produced and distributed in Mexico?
A: There are several mechanisms for seed production of improved varieties in
Mexico. The national seed program maintains the basic varietal stocks and
also markets seeds. Regional programs are becoming more active in bean seed
production since significant regional preferences exist for bean varieties
with specific color, seed size, maturity, culinary properties, etc. Regional
research stations are increasing specific bean types for test marketing in
their areas. The private sector also is an important factor in the bean seed
market.
Q: Will seed be available outside of Mexico?
A: Mexico is an active participant in regional testing programs involving other
countries and bean networks. Some discussions have actually taken place with
the World Bank about producing seed in Mexico for distribution in other
countries.
Q: Why is it so important to identify the specific physiological responses of
genotypes in selection for drought resistance.
A: Rainfall patterns in the highland regions of cultural Mexico are highly
variable. Even when early season rainfall is adequate, prolonged periods of
drought (up to thirty days) are not uncommon during the growing season.
Successful varieties must be able to survive these periods of moisture stress
and resume growth when adequate moisture becomes available. Well-adapted
varieties probably will have to employ more than one drought avoidance
mechanism.
-45-
NIGERIA/UNIVERSITY OF GEORGIA/UNIVERSITY OF NIGERIA
Kay McWatters and Dickson Nnanyelugo
Appropriate Technology for Cowpea Preservation and Processing and a Study
of Its Socio-Economic Impact on Rural Populations in Nigeria
Presenters: Kay McWatters, Dixon Phillips and Dickson Nnanyelugo
Milling Technology and Village Mill Installation:
Traditional wet decortication of cowpeas is time and labor intensive and produces
wet seeds which must be converted to food within a few hours to avoid spoilage.
The rationale of this project was to develop methodology for producing a ready-to-
use flour for akara and moin-moin production. Abrasive dry milling gave low
flour yields. Wetting cowpea seed to a moisture of -25 percent followed by
drying at temperatures of < 70C loosened the seed coat making it easy to remove
by abrasive or gentle impact milling. Grinding through a 1.0 mm screen resulted
in meal with excellent functional properties.
A small processing facility utilizing project milling technology has been
assembled and installed at Ogbodu-Aba (near Nsukka). This village was chosen for
its strong motivation and leadership. The mill building was erected largely by
community effort. A heated forced-air batch dryer, seed cleaner, plastic
steeping tanks, Engelberg rice dehuller, hammer mill, 3.5 kw generator, package
sealer and weighing scales were provided by the project. Mill products include
cowpea meal, cereal-cowpea flour blends and cowpea-based weaning food. A second
village mill is located in Isiala Ngwa, Imo State, as part of a State Ministry
of Health-AFRICARE Child Survival Project. This project features plots for
demonstrating improved crop production, the mill which produces cowpea and maize
meals as well as weaning foods, and a clinic which treats seriously malnourished
children and trains mothers in nutrition and child health. Plans are being
developed to "clone" this project at other locations in Imo State.
Processing/Storage Treatments Which Modify Cowpea Functionality and Nutrition:
Flatulence associated with cowpea consumption is attributed to the oligosaccha-
rides. Germination at 25, 30 and 350C for 12, 24, 48, and 72 hours reduced the
oligosaccharide content, improved the nutritional quality and altered the
functional properties of cowpea.
Cowpeas, like other legumes, develop the hard-to-cook (HTC) defect when stored at
high temperature and relative humidity (RH), rendering the whole seeds uncookable,
wasting fuel and compromising nutritional quality. Cowpea seeds were stored at
30, 37 and 44C and 76, 85 and 97 percent RH for up to six weeks to investigate
the reaction rate in development of the HTC defect. Accelerated storage at 37C
and 85 percent RH was also employed to produce HTC seeds for nutritional evalua-
tion. Studies have confirmed the development of HTC at high temperature/high
humidity conditions. The higher the temperature/humidity, the faster the rate of
hardening. Seeds stored at -180C or 30C/33 percent RH did not change with time
which indicates that low temperature/high humidity and high temperature/low
humidity combinations can prevent development of HTC.
-46-
Cowpea Meal Products: Their Formulation and Functional/Sensory Evaluation:
Akara (fried cowpea paste) is a sensitive food system for evaluating effects of
storage and process conditions on cowpea paste properties and end product
quality. Under ideal conditions, cowpea paste should have good water absorption
capacity, foam when whipped and have flow properties appropriate for dispensing
and frying. These properties have been shown to be mainly protein-related.
Storage, process and preparation conditions which produce cowpea meal and akara
that compare favorably with traditionally-made products in functional, sensory
and nutritional properties have been established. These conditions include
storage of peas at cool (2C) or mild (21C) temperatures, use of moderate
temperatures (50-90C) for drying peas that have been pretreated for mechanical
decortication, milling to a particle size distribution that concentrates 80-82
percent of meal particles in the 50-200 mesh range, and hydrating meal to a final
paste moisture of 58-60 percent. Objective methods to characterize the texture
and structure of cowpea products have also been developed and correlate well with
sensory measures. Functional behavior of meal made from germinated seeds was
satisfactory in preparation of akara. The flavor and texture of akara were
slightly different from the ungerminated control but were not objectionable.
Nutritional and Microbiological Evaluation of Cowpea Products:
Akara made from experimental meal was evaluated for protein nutritional quality
along with cowpea meal cooked by extrusion and kettle cooking/drum drying. Akara
and extruded products had a significantly improved protein efficiency ratio
compared to raw meal, but drum dried paste had reduced protein quality. Germina-
tion alone for 24 hour at 30C or shorter germination at 25 or 30C followed by
incubation effectively reduced oligosaccharide content and flatulence potential
of cowpeas. Germination increased thiamin, riboflavin and niacin content and
improved protein digestibility of cowpeas. The mean in vitro protein digesti-
bility of control cowpeas was significantly higher than that of HTC cowpeas. HTC
cowpeas which were ground to flour prior to cooking as paste or by extrusion
exhibited the greatest damage to protein quality. No effect on starch digesti-
bility was detected. The nutritional quality of various blends of cowpea with
cereals, animal protein and other legumes have been evaluated and shown to be
acceptable.
The moisture content of cowpea seeds and meal is normally too low to support
bacterial spoilage but may support growth of mycotoxigenic molds. Therefore,
the potential exists for growth and production of aflatoxin by A. flavus and
represents a health hazard. Higher quantities of aflatoxin were produced at
21 and 30C than at 37C on cowpea seeds, meal and onion-supplemented meal.
Aflatoxin was formed at aw, as low as 0.89. Death rate of bacteria, yeasts
and molds on cowpeas was more rapid at 350C than at 2 or 21C. Total microbial
populations in cowpea paste collected from three Nigerian markets were high
initially and increased after incubation. Coliform populations remained constant.
Predominant bacteria consisted of Enterobacter, Klebsiella and Lactobacillus
species; Candida species and Aspergillus niger were the predominant fungi.
Sorption isotherms of various cowpea products were determined and will be useful
in determining their storage stability.
Socio-Economic-Cultural Impact:
Consumption patterns, processing and storage problems and nutritional status of
low-income families have been determined through surveys conducted in Nigeria.
-47-
Cowpea is consumed once a week or more by >98 percent of the respondents in rural
and urban areas. Consumption is not influenced by family size, educational
background, marital status or occupation. Usual forms of preparation include
boiled seeds; moin-moin; akara; and mixes with yam or other tubers, rice and
maize. Although as many as 96 percent of families use cowpea for infant feeding,
anthropometric measurements of pre-school children showed that 13 percent were
mildly malnourished. Cowpeas are inadequately stored in jute bags, tins, drums,
plastic wares and earthen-ware pots. In one survey 49 percent of respondents in
one survey use techniques such as camphor, pepper, ganmaline and ashes as preser-
vatives. Processing of hydrated seeds is more often by manual than mechanical
means. The major constraints on cowpea consumption are the hard-to-cook defect
(42 percent of respondents), diarrhea (10 percent), indigestion (24 percent),
constipation (16 percent), and dislike (8 percent). Although 99 percent of the
respondents in one survey were unaware that new methods of preservation and
processing of cowpeas are now available, they expressed a desire to learn and
adopt these technologies.
Implications for Target Groups and Future Research Needs:
Increased cowpea consumption will improve nutritional status of Nigeria's rural
and urban poor. New technologies will promote employment opportunities and
increase and redistribute income. Village mills will serve as a catalyst to
promote development. Cowpea-based foods, especially akara, represent potential
channels for marketing cowpeas in the U.S. through institutional, fast food and
supermarket sectors. Increased demand for cowpea would reverse the diminishing
consumption of pulses and be an incentive for their increased production by
American farmers.
The ongoing nutritional, sociological and economic impact of the CRSP village
mills on villagers, especially women and children, should be evaluated over the
next five years. Further research into the mechanism and importance of storage
defects such as the HTC condition on reduced nutritional quality, increased fuel
use and wasted cowpeas is needed. Effects of cultivar on milling technology and
the functional and nutritional quality of resulting products need attention.
Fermentation and germination for making new/improved cowpea products should be
further investigated.
Planned Next Steps and Potential Linkages:
As this project is terminating on September 30, 1991, it will be necessary for
the University of Nigeria team to seek a new source of support for pursuing the
research needs mentioned above. The U.S. team has begun to seek an appropriate
site for continuation of utilization research. Research needs in the new
location will be identified during site visits in collaboration with scientists
in those locations.
-48-
Question and Answer period: NIGERIA
Q: Would the microorganisms found in cowpea paste survive the frying process in
preparation of akara?
A: This was not determined, but since the frying process is basically short-term
steaming, it is assumed that spores and some vegetative cells would survive
and present a potential health risk.
Q: Is aflatoxin produced on whole cowpea seeds and meal?
A: Cowpeas are not as good a substrate for aflatoxin production as corn, peanuts
or rice. However, aflatoxin can be produced under certain conditions of
temperature and relative humidity.
Q: Was there a problem of insect infestation during storage of cowpea meal?
A: No insect infestation of cowpea meal was observed under controlled storage
conditions in the U.S. Long-term storage of cowpea meal is not anticipated
and has not been studied under conditions in Nigeria.
Q: Has the problem of flatulence potential in cowpea weaning foods been
addressed?
A: Data showing reduction of flatulence by decorticating, steaming and frying
were collected from survey information and not from clinical studies. We
believe that processes such as germination, decortication and cooking would
eliminate problems associated with feeding cowpeas to infants.
Q: Has the project evaluated the milling effects of different cultivars?
A: Cultivar evaluation has not been the focus of this project up to this point.
The object was to develop a successful technology using a type of cultivar
already widely used and well accepted in Nigeria. We recognize the
importance of examining the effects of various cultivars in the future.
Comment: There was a comment that this project should be working with the
breeders.
Response: The project team believes in the importance of multidisciplinary
research. However, we contend that the responsibility for initiating such
cooperation lies as much with breeders as with food scientists. Further, we
believe that research cooperation must begin with joint planning at the project's
inception rather than as a request for analytical service later on.
-49-
SENEGAL/UNIVERSITY OF CALIFORNIA-RIVERSIDE/ISRA
A. E. Hall and Limamoulaye Cisse
A Program To Develop Improved Cowpea Cultivars, Management Methods,
And Storage Practices For Semiarid Zones
Presenters: A. E. Hall and Limamoulaye Cisse
Cowpea is a subsistence food crop for families on small farms in semiarid zones
of Africa, Asia and Latin America. In these semiarid zones, drought, heat,
diseases and pests seriously limit cowpea production and storage. ISRA and UCR
are collaborating in research to develop improved cowpea cultivars, management
methods and storage practices for the semiarid zone in Senegal and other
countries.
Developing Improved Cowpea Cultivars:
The overall strategy of collaboration and division of labor is that UCR has
emphasized the physiology and genetics of breeding for tolerance to heat,
adaptation to drought and yield potential, whereas ISRA has emphasized breeding
cowpeas with resistance to bacterial blight, mosaic viruses, cowpea weevil,
cowpea aphid and Striga. Effective cultivars for semiarid Africa would need most
of these characteristics, and this requires an integration of breeding activities
in the U.S. and Africa.
Heat tolerance: UCR has developed a model for heat tolerance based upon the
observation that high temperatures can damage different stages of development
during the reproductive period (Dh). The critical stages where cowpea is
sensitive to heat are the production of peduncles (Ped.) and flowers, and the
Grain Yield Dh Ped. Pods Seeds Weight
Gr= Yil =_ x x x ___
area area x day Ped. Pod Seed
number of pods set per peduncle. It should be noted that high temperatures
damage early floral bud development in bean as well. Physiological and genetic
studies at UCR established that heat sensitivity during early floral development
and pod set is partly due to genes involved in the phytochrome system that are
"hidden" and not expressed under optimal temperatures. Diverse cowpea accessions
from different countries and climatic zones, and including many important geno-
types bred by IITA, were screened under field and growth chamber conditions and
classified into eight groups based upon their tolerance to heat during repro-
ductive development under long days. Cowpeas in the Sahelian and Sudanian zones
of Africa are subjected to days that, initially, are longer than the critical
photoperiod and subsequently become shorter. Consequently, we have now begun
evaluating cowpea accessions for heat tolerance under short days using a
specially designed hot glasshouse. Results from the first experiment during the
fall and winter of 1990 indicated that certain cowpeas bred at UCR are heat
tolerant under short as well as long days, and differences in sensitivity to heat
were present under short days among photoperiod-sensitive cowpea genotypes from
Senegal and other countries in the Sahelian and Sudanian zones of Africa. We
have now bred cowpeas with substantial heat tolerance that are adapted to
commercial production conditions in California and provided heat-tolerant
germplasm to ISRA and a cowpea breeding program in Ghana.
-50-
Drought adaptation: UCR has developed a model for drought adaptation based upon
the observation that drought during the reproductive stages has quantitative
effects on grain yield of cowpea.
Grain Yield Dw Transpiration
= x WUE x HI
area E area x day
Where Dw is the duration of flowering and pod filling. In water-limited environ-
ments, the supply of water in the root zone influences both transpiration/day and
Dw and is influenced by depth of rooting. A method for screening genotypes for
depth of rooting under field conditions was developed, based upon observing plant
symptom response to an herbicide placed deep in the soil. This method was used
by UCR to evaluate cowpea accessions and is now being used in the peanut breeding
program of ISRA. Selecting and breeding for water-use-efficiency (WUE is the
ratio of plant biomass production to water use) has been constrained for all crops
by the difficulty in measuring WUE for large numbers of genotypes under field
conditions. Research at UCR has established that measurements of the heavy carbon
isotope composition of leaves, but not seeds, can be used to detect genotypic
differences in WUE. One unresolved physiological problem is that genotypic
differences in WUE were not associated with differences in the ratio of photo-
synthesis to transpiration measured on recently expanded leaves during the
afternoon, whereas drought-induced changes in WUE were associated with differences
in gas exchange. Genotypic differences in WUE were positively correlated with
biomass production under water-limited conditions, with only small differences in
water use. A crossing program has been initiated to breed cowpeas with higher
WUE. Research by other scientists has established that this methodology could be
effective with bean as well. Research in Australia with peanuts has indicated
the necessity of parallel selection for both WUE and harvest index (HI is the
ratio of grain yield to total biomass produced). We are not sure whether this is
necessary with cowpea, but we have established that genotypic ranking for HI
(based upon the ratio of grain yield to shoot rather than total plant biomass) is
not influenced by plant density. This indicates that selection for HI in cowpea
could be effective in early generations, such as the F2, with individual plants
grown at wide spacing. The duration of flowering and pod filling (Dw) has a
major impact on drought adaptation and yield potential under subsistence farming
conditions where multiple hand harvests of pods are practiced. We have discovered
genotypes with the combination of delayed leaf senescence and abundant pod
production. In field trials at UCR, one of these genotypes exhibited greater
adaptation to mid-season drought than a variety with typical leaf senescence.
The drought adaptation of the genotype with delayed leaf senescence was due to
greater ability to recover after the drought and produce a greater second flush
of pods than the variety with typical leaf senescence. Delayed leaf senescence
due to genotypic differences or pod-picking was associated with the accumulation
of large quantities of starch in the main stem. A rapid visual staining test for
starch in the main stem late in the season may provide breeders with a screening
technique for selecting genotypes with greater ability to resist mid-season
drought.
Yield potential: Cowpea varieties used for irrigated production in California
and for rainfed production in the Sudanian Zone of Africa could benefit from
increased yield potential. Research at UCR has shown that genotypes with pods
within the canopy have much greater efficiency in using light than genotypes with
pods held above the canopy. Presumably this loss in efficiency is due to pods
absorbing solar radiation and not using it as effectively in photosynthesis as do
leaves.
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Breeding for resistance to diseases: Bacterial blight and certain mosaic viruses
represent major constraints to cowpea production in Africa because these diseases
substantially reduce yield and are seed-borne. ISRA has established that the
cultivars presently used by farmers in Senegal are susceptible to these diseases.
ISRA has bred a cowpea genotype with resistance to these diseases and greater
yield stability than present cultivars. This genotype is being considered for
release as a new cultivar. Use of this cultivar by farmers would also reduce the
extent to which seed stocks are contaminated by these diseases. The research of
ISRA may be of benefit to California because UCR has recently discovered that
these diseases are present at low levels in California.
Breeding for resistance to insects: Cowpea weevil can severely damage cowpea
grain in storage and is one of the major constraints for the food and seed
supplies of subsistence farmers in Africa. The potential new cowpea cultivar
developed by ISRA was selected for resistance to cowpea weevil (in addition to
the resistance to diseases described earlier). In recent years, cowpea aphid has
caused substantial damage to cowpea production in Senegal and some damage to
cowpea production in California. Using a seedling screening technique, ISRA has
bred cowpea genotypes with resistance to cowpea aphid, but further research is
needed to select the genotypes that have both strong resistance to cowpea aphid
under field conditions and other desirable agronomic characters. Research at UCR
has demonstrated that the California biotype of the cowpea aphid is aggressive
and can overcome known sources of resistance, but we have recently discovered two
genotypes with partial resistance to this cowpea aphid.
Breeding for resistance to Striga: The parasitic weed, Striga, is a major
constraint for cowpea production in many parts of Africa. Until recently, it was
thought that cowpea striga was not present in Senegal. Research by ISRA has
shown, however, that cowpea striga is widely distributed in Senegal. ISRA has
begun screening cowpea genotypes from the CRSP Botswana project and the IITA
project in Burkina Faso to determine whether any of these genotypes have resis-
tance to the cowpea striga present in Senegal and would be useful as parents in a
breeding program.
Developing Improved Management Methods:
More than 90 percent of cowpea production in Senegal is from sole-cropped cowpeas
grown in rotation with pearl millet, peanut and occasional fallows. Earlier
research by ISRA has not shown any advantages to the intercropping of cowpea with
pearl millet in the Sahelian Zone where most cowpeas are grown. There may be
some advantage to the relay intercropping of cowpea with millet in the Sudanian
Zone which is wetter than the Sahelian Zone. The project has been evaluating the
hypothesis that varietal intercrops consisting of alternating rows of early-erect
and medium-cycle-spreading cowpea cultivars can improve the stability of cowpea
production under the harsh conditions of the Sahelian Zone. This research is
being conducted by a Senegalese student who has executed field experiments in
Senegal during the summer and fall, and laboratory studies and course work as
part of an M.S. program at UCR during the winter and spring. The research has
demonstrated significant advantages of the varietal intercrop over sole crops of
the same cultivars under either infertile or slightly improved soil conditions
with respect to the production of both grain and hay. This research has also
shown that low soil fertility is limiting cowpea production in the Sahelian Zone
of Senegal. Pods of early cowpeas are often harvested at the color-break stage
in Senegal as a source of food during the period of hunger and for sale. Field
studies at UCR demonstrated that longevity of the crop can be enhanced by
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removing color-break pods from cultivars which otherwise tend to senesce as pods
mature. In addition, these studies demonstrated that pod-picking can confer
greater resistance to mid-season drought by enhancing plant survival and the
ability of plants to produce more pods when the drought is ended.
Developing improved Storage Methods: ISRA has been conducting an extensive
series of on-farm tests of two methods for minimizing damage to cowpea grain due
to cowpea weevil during storage. These tests indicate that both methods, sealed-
drum storage and treating grain in sacks with K-Othrine PP2 at 50 g/100 kg, can
be effective. Socio-economic evaluations are being conducted to determine the
merits, advantages and problems of these two storage methods, and the cultivars
and management methods that are being evaluated in the on-farm tests.
Relevance of Technology Being Developed to Subsistence Farm Families:
The improved cowpea cultivars being developed by this project represent an
improved technology of extremely low cost that is equally available to farmers
with small or larger farms. The cost of producing seed of the improved cultivars
is less than present cultivars because the improved cultivars are more productive
per unit of input. The cultivars are self-pollinated lines and farmers can
obtain seed from their own food production fields. Disease-resistant cultivars
have more stable production and produce healthier seed than cultivars that are
susceptible to seed-borne diseases. Cultivars with resistance to insects can be
more productive and require less input of insecticides than cultivars that can be
damaged by insects. Varietal intercropping can be readily adopted on small or
larger farms because virtually all of the farmers producing cowpea in Senegal use
animal-draft equipment for sowing and cultivation. Adequate methods for improving
soil fertility are not yet available for most cowpea farmers in Senegal irrespec-
tive of farm size, but cowpea can be reasonably productive in infertile soils.
The sealed-drum method for storing cowpeas favors farm families that have the
capital to buy the drums, but the low cost of the K-Othrine PP2 (25 U.S. cents
to store 100 kg of grain) should not constrain the use of this technology on
small farms. The extensive on-farm testing and socio-economic evaluations being
conducted by ISRA will help to insure that the technology being developed to
improve cowpea production and storage is suitable for adoption by the vast major-
ity of cowpea farmers in Senegal who have small farms and limited resources.
For the future, progress in varietal improvement could be accelerated by
increasing collaboration among ISRA, UCR and IITA, and the project is progres-
sively increasing the level of interaction among the breeding programs.
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Question and Answer period: SENEGAL
Q: What type of evidence do you have for the genetic model of heat tolerance
that was presented, and would mixtures be as effective as varietal intercrops?
A: Mixtures may be less effective than varietal intercrops in Senegal for the
following reasons:
a. Mixtures of erect and spreading varieties could not be as efficiently
cultivated to control weeds as intercrops.
b. Separation of seeds during harvest would be more difficult with mixtures
than varietal intercrops--this would make it difficult to sell the grain
(mixtures are worth less in Senegal than uniform grain) or, if they had
the same seed characteristics, it would make it difficult to select the
proper proportions of seed for planting the following year.
Evidence for the genetic model was obtained as follows: Evidence for
the ph gene is described in the literature, PtI was described based upon
the segregation of F2, and backcross progeny, and individuals within F3
families and F3 families from several crosses. The Pt2, Pt3, and Pt4
genes and their epistasis have not yet been fully elucidated but data
from many crosses have been accumulated. The Hta and hbs genes were
described based upon the segregation of F2 and backcross progeny from
several crosses.
Q: Is it possible that the epistasis you proposed is really due to interactions
at the physiological level?
A: Yes, this is possible because the ph and pt genes appear to act through a
complex phytochrome control system.
Q: How expensive are the drums used in the method for storing cowpeas, and did
you use K-Othrine in the drums?
A: K-Othrine was not used in the drum treatments; they did not contain any
insecticide.
The drums are completely sealed, and it is the reduction in oxygen
concentration due to respiration of insects and seeds that kills the cowpea
weevils.
The cost of drums does limit the number of farmers who can afford this
technology, but drums are now being used by some farmers in Senegal. In
contrast, the K-Othrine is very cheap at approximately 250 for enough to
protect 100 kg of cowpea grain and widely available to farmers in Senegal.
Q: What is the evidence that carbon isotope discrimination may be useful for
detecting genetopic differences in water-use efficiency in common bean?
A: Data concerning genotypic differences in carbon isotope discrimination in
common bean have been obtained by Jeff White of CIAT and Mark Brick of
Colorado State University in cooperation with Jim Ehleringer of the
University of Utah at Salt Lake City.
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Q: What were the yields of the varietal intercrops and sole crops?
A: Average grain yields of the two intercrop combinations were 897 and 918 kg/ha
compared with 596, 640 and 758 kg/ha for the sole crops. The differences are
reasonably reliable because they represent means over two years, two locations
and two treatments with different low levels of soil fertility. The overall
yield levels may appear to be low but they were obtained in extremely harsh
environments in northern Senegal with low rainfall, sandy, infertile soil,
many biotic pests and high temperatures. Levels of yields on farmers' fields
in this region were approximately 400 kg/ha.
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TANZANIA/WASHINGTON STATE UNIVERSITY/SOKOINE UNIVERSITY
Matt J. Silbernagel and James Teri
Breeding Beans (Phaseolus vulgaris L.) for Disease, Insect and Stress Resistance
and Determination of Socio-Economic Impact on Smallholder Farm Families
Presenters: Matt J. Silbernagel and James Teri
Common beans (Phaseolus vulgaris L.) are a relatively minor crop in the state of
Washington. The 1988 production of snap beans for processing, dry beans for
consumption, and both dry beans and snap beans for seed had an approximate farm
gate value of only $21 million. Beans rank 23rd in a list of 40 commercial crops
grown state-wide which have an estimated total value of $3.67 billion. While the
State of Washington has never had a state-funded bean improvement program, the
USDA since 1957 has had a strong bean program at Prosser because of the regional
and national importance of seed production in the arid western desert states,
which maintain breeders and foundation seed stocks of the cvs needed in the mid-
western and eastern bean-producing states (as well as export needs). By producing
seed under rill irrigation in this hot, dry environment of Central Washington,
the seed-borne diseases of anthracnose, bacterial wilt, common bacterial blight,
halo blight and bacterial brown spot are held to zero tolerances. This practice
of seed production in the western states (to produce disease-free seed) has been
the primary means of control of the above diseases for the past fifty years.
However, under these conditions, viruses (bean common mosaic virus [BCMV] and
common tobacco virus [CTV]) and root rots (Fusarium, Pythium, Rhizoctonia) are
major production constraints.
The Collaborative Research Support Program between Washington State University
and Tanzania is deemed beneficial to the U.S. bean program (by U.S. research
administrators) because this collaborative effort allowed us to focus much needed
additional emphasis on bean common mosaic virus, which is important not only in
the U.S. and Tanzania but worldwide. Additionally, the CRSP support has also
allowed much more to be done in breeding for root rot and halo blight resistance.
Methodology and Results:
Research in the U.S. (Prosser) includes:
1. BCMV is genetically quite variable, readily aphid-transmitted and is seed-
borne. Because of international movement of bean seed lots, new strains can
appear almost overnight anywhere beans are grown. When these exotic new
strains are able to infect previously resistant local cultivars, the results
can be devastating.
Circumstantial evidence suggests that seed lots of BCMV-susceptible bean
cultivars that are produced in eastern or southern Africa by Dutch seed
companies often become infected with serogroup A isolates of BCMV and
eventually find their way to the commercial bean production areas of the U.S.
or Europe. Because there are currently no U.S. laws restricting bean seeds,
exotic BCMV isolates are not detected in commercial seed lots until economic
problems develop.
Under the Bean/Cowpea CRSP (1980-84), we produced nearly 600 hybridoma cell
lines which elicit antibodies specific for one or more BCMV strains. Cell
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culture supernatant were tested at that time against a panel of BCMV strains
collected from around the world; this panel included only four serogroup A
isolates. We selected one cell line from which we produced a monoclonal
antibody (which is now available commercially) that detected all known
strains of BCMV. Two additional MoAB lines were selected that are specific
for the serogroup A strains. There was considerable diversity in strain
specificity among the remaining 500-plus cell lines which are currently being
held in liquid nitrogen storage awaiting further evaluation. It is likely
that additional MoABs can be developed from this collection that will be
useful in discriminating both among serogroups and possibly among the
pathogroups defined on the basis of differential bean host cultivars.
2. Hundreds of hybrids have been made between U.S. and African cvs to combine
desirable plant and seed characteristics with sources of resistance to the
major disease problems in Africa (BCMV, rust, angular leaf spot, anthracnose,
halo blight, common blight) and the U.S. (BCMV, halo blight and root rots).
Further selection at Prosser and Morogoro have identified promising lines
that should lead to improved cvs for both locations.
Planned Next Steps and Potential Linkages:
In addition to what is outlined above, we are well into developing an improved
set of differential bean cultivars for the biological identification of strains
of BCMV. These differentials will all be based on the recurrent bush bean
parent, Stringless Green Refugee. A separate pair of near isogenic lines will be
selected which differ for each of the seven single genes for BCMV bean host
resistance (I, bcl, bcl2, bc2, bc22, bc3 and the non-specific gene bc U).
Dr. John Kneseck, Department of Microbiology, Texas Woman's University, Denton,
Texas and his graduate students will attempt to develop cDNA probes for each of
the seven host resistance genes using our near isogenic lines. In the future, it
may be possible with these probes to quickly determine which gene(s) for BCMV
resistance a parental or segregating hybrid line may have, without the laborious
time and space consuming efforts now required.
Being able to easily construct presently unavailable combinations of genes for
BCMV resistance will also allow us to identify strains of BCMV which are
presently undetectable with the now available bean host differentials.
Summary Report for Sokoine University of Agriculture:
Introduction: The common bean (Phaseolus vulgaris) is the most important
leguminous pulse food crop in Tanzania. Annual production (FAO 1988 estimate)
now stands at 240,000 metric tons from 400,000 ha. Average yields in farmers'
fields stand at 600 kg/ha although potential yields of 2,000 kg/ha in farmers'
fields have been demonstrated.
The major constraining factors to achieving the potential yields are lack of high
yielding varieties (HYV) that are resistant or tolerant to stresses like
diseases, pests and drought.
The major objective of the Bean/Cowpea CRSP in Tanzania has been to develop high
yielding, widely adapted, disease and insect resistant bean cultivars for the
smallholder family and to estimate the economic viability of the new cvs and their
impact on women's role in the production, consumption and marketing of beans.
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Methodology and results: Research in Tanzania has included the following:
1. Smallholder farm family surveys to establish baseline data on farm sizes,
family farm enterprises, production statistics, selection criteria of cvs,
gender issues in bean production and extension as far as reaching female-
headed households is concerned--Importance of beans in the farming systems of
the major bean growing regions of Tanzania has been documented including the
role of women in these farming systems. Problems of female-headed households
and selection criteria of bean cvs have been documented.
2. Germplasm collection, screening and improvement--The germplasm collected has
been screened for superior types. Crosses made among these and other lines
have been screened and superior types identified.
3. Screening segregating populations to identify lines resistant to rust, angular
leaf spot (ALS), BCMV, heat and drought.
4. Agronomic and physiologic studies of beans under monoculture, intercropping
and cultivar mixtures to identify superior cultural practices for beans.
5. The annual workshop reports documenting CRSP activities in Tanzania.
Implications for the small-scale farmer and for future research: The
technologies being generated (i.e., HYV resistant to insect pests, diseases and
other stresses, use of rock phosphate, BNF and cvs suitable for intercropping and
mixtures) are ideal cheap technologies for the resource-poor, small-scale bean
producers.
Earlier socio-economic research has shown the importance of women in bean
production, consumption and marketing and hence the need to develop technologies
which will enhance these roles. Of great concern are the female-headed
households which are poorer in resources and less reached by the extension
service.
Planned next steps and potential linkages: Joint studies are planned with the
CIAT/SADCC bean project in screening hybrid segregants against beanfly and
nematodes and in farmer participatory research. There is a joint (SUA/CIAT)
supervision of a Ph.D. student from Uganda.
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Question and Answer period: TANZANIA
There was a discussion on the philosophy of utilizing a single cultivar (pure
line) verses mixtures of genotypes (landrace situation). About 25 percent of
acreage is planted with pure lines and the remaining 75 percent is small farm
acreage with mixtures predominating. Thus both strategies should be used in the
project.
Seed multiplication and distribution were cited as problem areas to be
addressed. Growers should be identified, seed distributed and impact should be
studied. CIAT/SUA/Tanzanian government are cooperating in three ecological zones
(low, middle and high altitude) for breeding line evaluation and this could be
utilized for seed distribution.
A question was raised about how to handle the post harvest nutrition/cookability
aspects. Although some work is being done in this area, strengthening was
suggested. Similarly, post harvest storage (75 percent of the beans are used on
farm) work needs to be done to deter bruchids which are the main problem.
Clarification was made on the issue of what criteria are used to discard breeding
materials (i.e., pest susceptibility and lack of adaptation are top priorities).
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THE ROLE OF FOOD SCIENCE AND TECHNOLOGY IN THE DELIVERY SYSTEM:
UNDERSTANDING THE GAME PLAN
T. 0. M. Nakayama
Department of Food Science and Technology
University of Georgia
Food science and technology has been defined as the application of the natural
sciences to the processing and distribution of foods. This descriptive
definition, however, does not allow for interpretations on how the various facets
interact with each other and the food delivery system as a whole.
I will attempt here to give you some idea, albeit a personal view, on what the
requirements of the delivery system demand and how the various CRSPs can play a
part in organizing the delivery systems in developing countries.
A basic premise is that social organizations exist for the purpose of creating
wealth by lessening labor required for the essentials. The organization of a
family traditionally has brought specialized roles for males and females. The
organization of family units into communities has further benefits of mutual
protection and division of labor, which has the increased ability to simplify
tasks. Even the most rudimentary tasks consist of multiple operations. If these
could be separated and each family perform one task, this would result in an
increase in efficiency. For instance if an apparatus were to be made of three
different parts, each family could make one part and the fourth could be
responsible for assembling this apparatus. Because of specialization, a greater
degree of efficiency, and probably quality, would result. However, this type of
communal behavior requires coordination and mutual trust depending upon whether
one lives in an autocratic unit or a democratic one.
An organized society may utilize increased efficiency by engaging in the creation
of further wealth. Wealth is a matter of creation by societies and is a distinct
human endeavor.
In animals, one might note that herd behavior is often controlled by a single
dominant individual. Similarly, many of the large projects such as pyramids,
great walls and palaces were essentially created by individuals or elite groups
governing the masses. On the other hand, wealth can be created in a more
participatory society through what is commonly known as a democratic process.
Our country is evolving toward this end.
Food is a necessary and continuing need for all peoples and, thus, it behooves
any society to coordinate the food delivery system so that this need can be met
with least input in order to conserve resources for other activities. The food
delivery system has as its-primary function the provision of food for the
populace. Food is the instrument of delivery of nutrients for people. Thus, the
human can be considered as an isothermal machine which requires about 2500 K
calories/day and sufficient nutrients to repair itself. The energy to be
utilized must be in the form of chemical bonds which can be broken and the
resultant energy utilized at constant temperature. These bonds are found in
biologically derived materials, both plant and animal. Thus, one can use an
analogy from the Second Law of Thermodynamics and say that consumed food equals
total food produced minus that lost, wasted, or used elsewhere. However, because
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the process is at constant temperature, thermal considerations are not as
important. During production phases of a foodstuff, also known as growing, the
total amount of energy reserve increases to a maximum until the time of harvest
or slaughter, as the case may be, and thereafter decreases eventually returning
to standard conditions. Thus, the act of harvest is an identifiable point.
The other point to be noted is that part of the system which is analogous to
entropy is constantly decreased during production. That is, random molecules of
carbon dioxide, nitrogen and water are being organized into starch, protein, fat
and other cellular components by the use of radiant/chemical energy. After
harvest, while the total amount of food is reduced, the amount of waste is also
decreased or increased depending on the circumstances. Under natural conditions,
the food material spoils and returns to the original random state of molecules.
On the other hand, through human intervention the amount that would be lost is
decreased. The very essence of preservation is to keep food in a state which is
utilizable until eaten. Thus at the point of consumption, the total amount of
available food is decreased by perhaps less than half but the amount wasted is
decreased also, resulting in a net increase in value. After consumption, the
randomness of the molecules increases to eventually yield carbon dioxide, water
and energy. Thus, harvesting and consumption are easily identifiable points in
this delivery system. It is between these points that the role of food science
and technology can be discerned.
Foods, while an instrument of delivery, have several facets which appeal to
different senses; thus, foods are difficult to compare in simple systems such as
the often heard "You can't compare apples and oranges." However, a common
experience for most people is to walk into a supermarket and decide whether to
buy apples or oranges. Thus, that which cannot be compared is obviously done
everyday. However, what exactly are we comparing? The integrating instrument
here is value. Value of anything is equal to the amount or quantity times a
factor (an objective quality) times a probability of acceptance/consumption.
Value quantity x quality x probability
costs = costs
Cost, of course, is labor and energy, but also societal cost, environmental cost,
etc. This very general equation can be used to understand the role of food
science and technology in the CRSPs.
"Value added" is that increase in value of a foodstuff beyond the point of
harvest. This includes such things as perceived values, which impact on the
probability of acceptance. Typically, value added is about twice that of the
value at harvest in the U.S. In developing countries it can be as much as ten
times. The purpose of an organized effort as previously stated is to create
wealth. In order to create wealth, you must increase value. This consists of
optimizing the ratio of the above equation by maximizing the numerators and
decreasing the denominator. The probability of consumption, as you can guess, is
a multiple of many probabilities such as the probability of the price being
correct, the probability that the color is right, the shape is right, the taste
is good, etc. As you can note, these probability and quality factors are largely
socio-economic or sociological in origin while the quantity and costs are heavily
technological. However, it should be noted that these factors are to be
multiplied. They are not additive. Thus, one may have large values for quantity
and quality and low values for cost; however, if the probability of acceptance is
low, the value is low. If one were to perhaps limit quantity, then in order to
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maximize value, one must raise quality and probability of acceptance. This
equation, which should intimidate no one, helps us understand why, with produce
such as beans and cowpeas, the quality appears to be the best when the price is
the lowest--when it is the height of the season. Value is a human connotation
and thus, heavily dependent on sociological factors. Today, some of the
prominent factors affecting probability of acceptance include such considerations
as nutritious, healthful and light which are bolstered by such terms as natural,
organic and low calorie in developed countries. The probability of acceptance in
developing countries is more likely to be affected by ease of cooking, low inputs
for production, digestibility, familiarity, etc.
Let us trace some foodstuffs through the system. When a seed is planted, there
is virtually no potential food here. However, as the crop (for instance, beans
or cowpeas) matures, it is quite apparent that there is a great deal of value
here. The fact that the net effect is positive with respect to value can be seen
in small huts that the growers erect in fields to guard against thievery near
harvest time. Once harvested, there is, of course, storage and distribution,
both of which increase the value of beans and cowpeas by making them more
acceptable and less prone to deterioration by insects, molds and rodents. Beans
and cowpeas subjected to all of these operations have maximum value. After the
beans or cowpeas are eaten, of course, the energy is expended and eventually the
molecules are returned as carbon dioxide and water.
A similar scenario might be enacted for animal products which reach a maximum at
slaughter and then are processed, transported, etc. and finally consumed. The
animal system, of course, requires an input from plant sources to furnish the
energy necessary to grow and develop. Efficiency here is about 10 to 1 in terms
of energy. Sociological considerations also impact heavily. Dietary taboos, of
course, render certain products with very low probabilities of acceptance, thus
negating their value. Likewise, products suspected of containing undesirable
chemicals lose a tremendous amount of value. Because this task of keeping the
food delivery system going is a continuing one, the more efficient the system,
the less resources must be spent by the society. The measure of this, of course,
is the amount of disposable income used for food, which in our country is quite
low. Further sociological efforts need to be expended on utilizing excess
resources for constructive value increases rather than destructive ones--drugs,
crime, etc.
The combination of organized effort and technological possibilities make it
possible for more developed countries to transfer some of this know-how to less
developed countries who are still largely in the subsistence mode. An attitude
of self-sufficiency and going-it-alone is a sure road to poverty for any society.
An example of technology transfer is the use of wheat and the location of flour
mills. Of the fifteen largest flour mills in the world, seven are located in
countries growing virtually no wheat. In Nigeria one can see bread sold in every.
rural village. The acceptance of bread has formed the basis of a large industry,
and efforts are underway to grow wheat. It has also rendered the country captive
to the wheat producers.
But there is no doubt that without mills, the enjoyment of bread would be only
for the rich in these countries. The milling of grains is a fundamental method
of preparation which ranges from a mortar and pestle to ready-made flours. This
operation is a part of a woman's chores at the subsistence level and man's at the
industrial level. An analogous case to wheat can be made for the milling of
other grains.
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An index of development in any society is the worth of a woman's time. The
lessening of her burdens would enable her to devote more of her time to pursuits
which would enrich her life and that of her family. Societies which relegate
their women to a permanent underclass are marked by stagnation.
Food science is concerned with the properties of foods and their transformations,
while technology entails the application of this information for specific ends
and includes food processing, etc. The closer to the consumer the delivery
system comes, the higher the value and, thus, the higher the intellectual
properties associated with the product. Brand names, processes, etc. are
generally protected under the aegis of intellectual property by such things as
patents, copyrights, show-how, know-how. Most research in land grant colleges in
food science deals with properties of foods and their transformations and in a
limited way with process conditions and technology--that is, process design and
implementation. These latter elements are in the province of the industry which
has a great stake in them. For developing countries, however, the show-how and
know-how must be developed with great care. If one were to transfer the
technology of the system directly to another country, that would best be done by
industry since industry has the know-how to do this. I raise my contention that
the place of the land grant institution is what it has traditionally been in our
own country. That is, to lay the foundation information for all to use which
would then be applied by the practitioners. Thus, in the training phase of the
CRSPs, the principles of food science can be learned and the aspects of
technological requirements known. The actual implementation of these, however,
would be best left to those practitioners in the Host Countries. In this way,
what is created would be sustainable technology. Many examples of inappropriate
technology transfer have occurred which tend to make them instructive via the
experience route. Thus, food science has a definite and indispensable role in
the development of food delivery systems in developing countries. It fulfills
this role by interacting in a purposeful fashion with the natural and the social
sciences necessarily impacting on women in development, technological resources,
natural resources and political organizations.
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Question and Answer Period: Food Science and Technology in the Total Food
Delivery System
Comment: Producers feel that value added to commodities by the processing,
distribution and marketing of foods is overrated.
Response: This is a common feeling expressed by producers. However, in the
equation for value (see page 3 of Dr. Nakayama's written summary), more effort is
put in countries or situations where quantity is plentiful. Anything a consumer
is willing to pay for is real value.
Q: What can the CRSP do to link more closely the concerns of consumers and
producers?
A: This is a problem of communication and the need for understanding what each
group needs. Food Science and Technology works between the consumer and the
producer and can translate those needs.
Q: What should Food Science and Technology be doing in the CRSP?
A: The role of Food Science and Technology should be to save foodstuffs
produced by decreasing waste and making food more appealing to the consumer
by building in or adding value. Also, an extremely important component is
the training of people and the development of human capital.
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IDENTIFICATION, MAPPING AND USES OF
RESTRICTION FRAGMENT LENGTH POLYMORPHISMS
Michael J. Havey
Vegetable Crops Research Unit, USDA/ARS
Department of Horticulture
University of Wisconsin
In diploid plants, two alleles reside at a given genetic locus in each
individual. For morphological traits or disease resistances, the alleles are
distinguished by different phenotypes such as blue versus white flower petals,
resistant versus susceptible, tall versus dwarf plants, etc. If allelic
variability is present at numerous genes, the physical ordering of the genes on
individual chromosomes can be estimated. The relative positioning (mapping) of
genetic loci is elucidated by crossing between plants possessing different alleles
and studying the numbers of parental versus recombinant progeny. Alleles at loci
that are closely located on the chromosomes have a greater probability to be
inherited as a unit. This physical linkage of genetic loci is expressed as a
greater proportion of progeny possessing the phenotype of the parents. Using
classical genetic markers such as morphological traits and disease resistances,
plant geneticists have developed detailed genetic maps for a few species, e.g.,
pea, maize and tomato. However the number of classical genetic markers are
limited and, as a result, most plant species have very rudimentary genetic maps.
Biochemical markers, such as isozymes, have increased the number of loci that are
mappable, but the numbers of variants are still inadequate to generate detailed
genetic maps of most species.
Recent advances in molecular biology have led to the discovery of a new class of
genetic marker. Restriction enzymes are proteins that cut the DNA at specific
sequences of either 4-, 6-, or 8-base pairs. Because the restriction enzyme
recognizes a specific sequence, a mutation changing one base pair in the
recognized sequence would result in the loss of the site at which the DNA is cut.
Insertion or deletion of DNA between two restriction enzyme sites can also change
their relative location. DNA fragment size differences between plants, breeding
lines or populations due to changes in the positions of restriction enzyme sites
are called restriction fragment length polymorphisms (RFLPs). RFLPs have a
genetic basis and are inherited as simple Mendelian factors. Because RFLPs
represent changes in the DNA of the plant, they can be detected in all tissues and
at all stages of plant development. Adequate numbers of RFLPs have been
identified in numerous plant species allowing for the development of genetic maps
at a level of detail not possible using classical markers and isozymes, e.g.,
maize, tomato, rice, potato, lentil, lettuce (Bernatzky and Tanksley 1986,
Helentjaris et al. 1986, Landry 1987, Bonierbale et al. 1988, McCouch 1988, Havey
and Muehlbauer 1989).
Detection of RFLPs is presently expensive and technically difficult (Beckmann and
Soller 1983). After digestion with a specific restriction enzyme, plant DNA is
size-fractionated through an agarose gel, denatured and transferred to a
supporting membrane. Unique cloned fragments (probes) of DNA from the plant are
radioactively labeled, heat denatured and added to a solution surrounding the
digested DNA on the supporting membrane. These probes will hybridize only to
complementary sequences of DNA on the supporting membrane. Because the probe DNA
is radioactive, the location of the complementary sequences can be detected by
autoradiography. RFLPs are therefore identified as differences in the sizes of
bands on X-ray film. The cost of identifying RFLPs will soon become less costly
with the advent of new approaches, such as the polymerase chain reaction.
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The genetic characteristics of RFLPs include a Mendelian mode of inheritance,
co-dominance, multiple allelic forms and lack of pleiotropic effects on
economically important traits (Beckmann and Soller 1983). RFLPs are useful for
line identification, plant variety protection and measurement of genetic diversity
(Bailey 1983, Soller and Beckmann 1983). They can provide a means of monitoring
the level of heterozygosity or homozygosity in a population, analyzing
quantitatively inherited traits and assisting in the introgression of useful
traits in segregating populations (Beckmann and Soller 1983, Burr et al. 1983,
Tanksley 1983, Helentjaris et al. 1985). Markers have been used effectively to
assess genetic diversity within and between plant populations (Helentjaris et al.
1985) and to identify and select for monogenic or polygenic traits in crop
improvement programs (Edwards et al. 1987, Stuber et al. 1987). RFLPs have been
used to identify genes conditioning quantitatively inherited traits of economic
importance in tomato, e.g., high soluble solids, water use efficiency and insect
resistance (Osborn et al. 1987, Paterson et al. 1988, Nienhuis et al. 1988,
Tanksley and Hewitt 1988, Martin et al. 1989). RFLP linkage maps can potentially
facilitate the more efficient use of resources in a practical plant breeding
program. Traits with relatively high heritabilities and which are expensive or
time-consuming to evaluate may be improved by selecting for tightly linked marker
loci (Beckmann and Soller 1988). Therefore, the use of RFLPs as tools in plant
improvement programs is likely to expand in the future.
References
Bailey, D. C. 1983. Isozymic Variation and Plant Breeder's Rights. In S. D.
Tanksley and T. J. Orton (eds.) Isozymes in Plant and Genetics and Breeding.
Amsterdam: Elsevier Co.
Beckmann, J. and M. Soller. 1983. Restriction Fragment Length Polymorphisms
in Genetic Improvement: Methodologies, Mapping and Costs. Theory of Applied
Genetics 67:35-43.
Beckmann, J. and M. Soller. 1988. Detection of Linkage Between Marker Loci
and Loci Affecting Quantitative Traits in Crosses Between Segregating
Populations. Theory of Applied Genetics 76:228-236.
Bernatzky, R. and S. D. Tanksley. 1986. Toward a Saturated Linkage Map in
Tomato Based on Isozymes and Random cDNA Sequences. Genetics 112:887-898.
Bonierbale, M., R. Plaisted, and S. Tanksley. 1988. RFLP Maps Based on a
Common Set of Clones Reveal Modes of Chromosomal Evolution in Potato and
Tomato. Genetics 120:1095-1103.
Burr, B., S. V. Evola and F. A. Burr. 1983. The Application of Restriction
Fragment Length Polymorphisms to Plant Breeding. Genetic Engineering 5:45-59.
Edwards, M., C. Stuber, and J. Wendel. 1987. Molecular-Marker-Facilitated
Investigations of Quantitative-Trait Loci in Maize. I. Genomic
Distribution, and Types of Gene Action. Genetics 116:113-125.
Havey, M. and F. Muehlbauer. 1989. Linkages Between Restriction Fragment
Length, Isozyme, and Morphological Markers in Lentil. Theory of Applied
Genetics 77:395-401.
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Helentjaris, T., King, G., Slocum M., Siedenstrang, C. and S. Wegman. 1985.
Restriction Fragment Polymorphisms as Probes for Plant Diversity and Their
Development as Tools for Applied Plant Breeding. Plant Molecular Biology
5:109-118.
Helentjaris, T., M. Slocum, S. Wright, A. Schaefer, and J. Nienhuis. 1986.
Construction of Genetic Linkage Maps in Maize and Tomato Using Restriction
Fragment Length Polymorphisms. Theory of Applied Genetics 72:761-769.
Landry, B., R. Kesseli, B. Farrara and R. Michelmore. 1987. A Genetic Map of
Lettuce (Lactuca sativa L.) with Restriction Fragment Length Polymorphisms,
Isozymes, Disease Resistance Genes, and Morphological Markers Genetics.
116:331-337.
Martin, B., J. Nienhuis, G. King and A. Schaefer. 1989. RFLPs Associated with
Water Use Efficiency in Tomato. Science 243:1725-1728.
McCouch, S., G. Kochert, Z. Yu, Z. Wang, G. Khush, W. Coffman and S.
Tanksley. 1988. Molecular Mapping of Rice Chromosomes. Theory of Applied
Genetics 76:815-829.
Neinhuis, J., T. Helentjaris, M. Slocum, B. Ruggero and A. Schaefer. 1987.
Restriction Fragment Length Polymorphism Analysis of Loci Associated with
Insect Resistance in Tomato. Crop Science 27:797-803.
Osborn, T., D. Alexander and J. Forbes. 1987. Identification of RFLPs Linked
to Genes Controlling Soluble Solids Content in Tomato Fruit. Theory of
Applied Genetics 73:350-356.
Paterson, A., E. Lander, J. Hewitt, S. Peterson, S. Lincoln and S. Tanksley.
1988. Resolution of Quantitative Traits into Mendelian Factors by Using a
Complete Linkage Map of Restriction Fragment Length Polymorphisms. Nature
335:721-726.
Soller, M. and J. Beckmann. 1983. Genetic Polymorphism in Varietal Identi-
fication and Genetic Improvement. Theory of Applied Genetics 67:25-33.
Stuber, C., M. Edwards and J. Wendel. 1987. Molecular-Marker-Facilitated
Investigations of Quantitative Trait Loci in Maize. II. Factors Influencing
Yield and its Component Traits. Crop Science 27:639-648.
Tanksley, S. 1983. Molecular Markers in Plant Breeding. Plant Molecular
Biology 1:3-8.
Tanksley, S. and J. Hewitt. 1988. Use of Molecular Markers in Breeding for
Soluble Solids in Tomato--A Re-examination. Theory of Applied Genetics
75:811-823.
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STATUS OF BEAN RESEARCH AT CIAT:
STRATEGIC OBJECTIVES FOR THE 1990s
Douglas Pachico and Julia Kornegay
Bean Program, CIAT
Cali, Colombia
During the decade of the eighties, the principal research objective of Centro
International de Agricultura Tropical's (CIAT) bean program was to improve bean
varieties for resistance to diseases and insects. Disease resistance breeding
was given the highest priority. The justification behind these decisions was
based on the widespread importance of diseases throughout Latin America and
Africa, the fact that most diseases are seed-borne and persist because bean
farmers in the tropics usually save their own seed and due to the difficulty to
control disease by non-genetic means. The bean program believed that multiple
disease resistant varieties would reduce production costs and risks and thereby
make bean production more profitable to both farmers and less expensive for
consumers.
During the 1980s plant breeders, plant protectionists and agronomists were
trained both at CIAT and within their regions. Emphasis was placed on on-farm
research training with the objective to help increase national program capacity
to set priorities and evaluate the new technologies. Also during this time,
regional research networks were set up in both Latin America and Africa to
provide the means by which scientists or different countries could collaborate on
specific research problems and share their results. These research networks were
guided by steering committees composed of national program leaders, who advised
CIAT and the networks on the priorities for future research and training
activities. Within CIAT's Bean Program, fifteen scientists are out-posted in
regional network projects in Latin America and Africa, and eleven program staff
are based at Headquarters in Cali, Colombia.
At the end of the 1980s, the Bean Program had consolidated its efforts in Latin
America and Africa building stronger ties with national research and development
systems and decentralized an increasing share of its applied research objectives
to national programs within regional networks. Measurable impact was already
seen in farmer's fields, with more than 50 improved varieties grown by farmers on
more than 350,000 hectares. Based on these achievements, the Bean Program began
the decade of the nineties with a strategic review of its changes needed to
increase bean production and productivity for small-scale farmers and poor
consumers of the tropics. To design the new research strategies for the 1990s,
an extensive, interactive process involving CIAT scientists, external advisors
and consultations with many national program leaders was initiated. Five
strategic objectives were prioritized for the bean program.
Strategies for the 1990s
National programs are highly heterogeneous with different capacities and needs.
Many countries have limited resources and the interaction between research,
extension and farmers is weak. In general, little attention is paid to the
long-term effects of current cultural practices. To deal with these problems,
the first strategic objective will be the continued high priority of strength-
ening national program capacity to improve bean productivity in diverse cropping
systems. The strategies to accomplish this objective are: (1) to deliver
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to national programs genetic materials as parents, segregating populations or
finished lines according to their needs; (2) link national programs more
strongly into research networks to solve common problems and exchange results;
(3) strengthen national program capacity to involve farmers in setting research
priorities and technology evaluation; and (4) stimulate national programs to
develop sustainable and productive crop management systems.
Specialized training, coordination with network activities and collaborative
research projects are essential components in the implementation of these
strategies. Technology development must be based on the realistic needs and
abilities of national programs to implement and diffuse new solutions to bean
production problems.
Reduce losses from pests and diseases. Although much progress has already been
achieved in this area, further effort is needed to: (1) broaden the genetic base
of resistance sources; (2) identify sources of resistance where lacking and
incorporate the genes conditioning resistance into acceptable cultivars; and
(3) develop integrated control strategies to complement genetic resistance while
reducing pesticide application.
The increasing use of pesticides by small farmers in Latin America is a growing
problem. Pesticide abuse is becoming more prevalent. Although multiple disease
and insect resistant varieties will help alleviate this situation, it is
difficult in many cases to breed resistance to all the biotic constraints present
in a given production environment. The combination of resistant varieties and
Integrated Pest Management (IPM) practices is needed. The development of
suitable IPM practices which can be easily taught and used by small farmers is
beginning, but more is needed.
The overall soil fertility in bean-based systems is declining because of expan-
sion of beans into marginal soils, shortened fallow periods, soil erosion and
limited use of fertilizer, especially in Africa. Over half of the area planted
to beans is also subject to drought stress. Significant research is needed in
these areas. A start was made during the 1980s to improve the efficiency of
nutrient and water use by bean plants, however, significant challenges remain to
be solved. To relieve nutrient and drought constraints four strategies are being
pursued: (1) breed bean genotypes with improved ability to fix nitrogen;
(2) identify mechanisms and develop efficient screening methods for tolerance to
low phosphorous and to acid soils; (3) generate bean genotypes with improved
adaptation to water stress; and (4) stimulate national program research in
fertility management for bean-based cropping systems.
With the increasing availability of bean varieties with multiple disease and
insect resistance there is a growing demand by national programs to increase the
yield potential of beans. Little progress, however, has been made in this area,
especially among the medium to large seeded types preferred in many countries.
Research to tackle this problem has begun and includes: (1) placing a greater
emphasis on selection for yield in the breeding nurseries; (2) exploring the
genetic variation across gene pools as a means to optimize genes controlling
yield; (3) attempting growth habit modifications in medium-large seeded types to
produce more productive plant types; and (4) studying yield maximizing physio-
logical traits such as canopy morphology and patterns of nitrogen uptake and
partition to determine which factors can be optimized for higher yield potential.
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The final strategic objective of the bean program is to improve methods for
utilizing Phaseolus genetic resources by: (1) studying the patterns of genetic
diversity to prioritize new resource acquisitions; (2) utilize biochemical
markers to increase the efficiency of conventional breeding; (3) evaluate the
potential for increased utilization of wild ancestors and related species for
common bean improvement; (4) apply new methods for gene transfer; and (5) link
biotechnology research institutes in developed countries to priority problems of
beans in the tropics through advanced research network on beans.
Progress in molecular biology offers the opportunity of more efficient identifi-
cation and transfer of useful genes, both within P. vulgaris and from related
species. CIAT has a comparative advantage in identifying these genes through
evaluation of its collection of Phaseolus genetic resources. However, the
collection is too large (more than 40,000 accessions) for in depth evaluation of
its materials. CIAT is in the process of forming a subset or core collection of
the genetic variability present in the total collection, which will facilitate
the use and evaluation of useful genes.
In the scope of this presentation, it is not possible to give the details of the
specific research projects that will be done to accomplish the objectives
outlined in the strategic plan for the 1990s. The challenges are great and the
research that is needed will require innovative approaches to understanding and
solving these problems.
Conclusion
To achieve the five strategic objectives of CIAT's bean program in the next ten
years, shifts in resources will be made, and some research areas of the 1980s will
be reduced to make way for the new research of the 1990s. More reliance will be
made on collaboration with our national partners in Latin America and Africa and
with advanced research networks, such as the CRSP, in the developed countries.
The goal of increasing food availability and income to the poor by improving bean
productivity requires basic, strategic and applied research. We hope that our
strategic plan will stimulate CRSP scientists to shift more of their resources
towards the basic and strategic research areas that are outlined in this paper.
The results of this research will be beneficial not only to CIAT and our national
partners by alleviating bean production constraints, but will also benefit bean
farmers and agricultural science in the developed countries as well.
References
Cardona, C., J. Kornegay, C. E. Posso, F. Morales and H. Ramirez. In press.
Comparative Value of Four Arcelin Variants in the Development of Dry Bean Lines
Resistant to the Mexican Bean Weevil (Coleoptera: Bruchidae). Entomologia
Experimentalis et Applicata.
Cardona, C., C. E. Posso, J. Kornegay, J. Valor and M. Serrano. 1989.
Antibiosis Effects of Wild Dry Bean Accessions on the Mexican Bean Weevil and
the Bean Weevil (Coleoptera: Bruchidae). Journal of Economic Entomology
82:310-315.
CIAT. 1989. CIAT in the 1990s: A Strategic Plan. Cali, Colombia. 58p.
-71-
CIAT. 1989. CIAT Annual Report. Bean Program, Cali, Colombia.
Kipe-Nolt, J. and H. Vargas. 1989. Components of Nitrogen Fixation in Phaseolus
vulgaris. In S. Beebe (ed.) Current Topics in Breeding of Common Beans.
Working Document No. 47. Bean Program, CIAT, Cali, Colombia, 438P.
Laing, D. R.. 1990. Incremento de la produccion de granos basicos, utilizando
menos insumos en agriculture sostenida. Conferencia Magistral. PCCMCA.
Reunion XXXVI. El Salvador, Marzo 26, 1990. CIAT, Cali, Colombia.
Lynch, J., A. Gonzalez and J. Tohme. 1990. Variation in Characters Related to
Leaf Photosynthesis in Wild and Weedy Bean Populations. Submitted to Crop
Science.
Lynch, J. and J. W. White. (In preparation). Aspects of Nitrogen Use Efficiency
in Common Bean and Other Grain Legumes in a Tropical Environment.
Pachico, D. and A. van Schoonhoven. 1989. A Post-Green Revolution Strategy for
the Improvement of Small Farmer-grown Common Beans. Tropical Pest Management.
35:243-247.
Valasquez, J. G., P. Prada and G. Henry. 1990. Snap Bean Pests and Diseases in
Sumapaz, Colombia: Their Present Status and Implications. In G. Henry and
Janssen (eds.), Snap Beans in the Developing World. Proceedings of an
International Conference. CIAT, Cali, Colombia, October 16-20, 1989.
White, J. W., J. Kornegay, J. Castillo, C. H. Molano, C. Cajiao and G. Tejada.
1990. Effect of Growth Habit on Yields of Large-seeded bush cultivars of
common bean. In preparation for Field Crop Research.
White, J. W., J. Kornegay and C. H. Molano. 1990. Photoperiod response of
flowering in snap bean germplasm. Submitted to Journal of the American Society
of Horticultural Science.
-72-
Question and Answer Period: Status of Bean Research/CIAT
Q: What has been the yield stability of isogenic lines expressing the Type I
growth habit vs. Type II or III growth habit?
A: On the average, Type I lines were more stable than Us or IIIs. However,
some individual lines with II or III growth habit were shown to be
relatively stable in the environments measured.
Q: Have lines with a high arcelin content been tested in comprehensive
nutritional studies?
A: Yes. They have been tested in several laboratories in various nutritional
trials. No problems were identified. Furthermore, arcelin appears to be
labile at normal cooking temperatures and times.
Q: To what degree is there acceptance by farmers and users of this improved
materials traceable to CIAT germplasm.
A: Comprehensive testing is done in each area by teams of researchers from the
respective areas. Data have been collected on standard parameters such as
seed size and color, cooking time, hard seed formation and taste.
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CURRENT STATE OF COWPEA RESEARCH FROM IITA'S PERSPECTIVE
AND THE MAJOR RESEARCH NEEDS FOR THE FUTURE
S. R. Singh
Grain Legume Improvement Program
International Institute of Tropical Agriculture
Ibadan, Nigeria
Introduction
IITA launched a strategic planning study in 1986, from which was developed its
Strategic Plan 1989-2000. The implementation of the long-term Strategic Plan is
being carried out on a phased basis, the first phase of which is the Medium-Term
Plan 1989-1993. The focus is on the smallholder African farmer or family farmers
in five agroecological zones of West and Central Africa.
Cowpea is the predominant grain legume crop in most of the region, and is
marketed and consumed throughout all zones. It is an important cash and food
crop in the Sahel/dry savanna and is also a major grain legume in the moist
savanna, transition and inland valleys. Cowpeas vary in maturity, plant type and
seed characters due to the diversity in the cropping systems in the various
agroecological zones. The constraints in cowpea production vary according to
cropping systems and ecologies. There is need for site-specific research.
IITA's Cowpea Improvement Program
IITA has a global mandate for cowpea research in the CG system. IITA's cowpea
improvement program works closely with national programs in Africa. IITA
scientists participate with national scientists in the development of research
plans at IITA and at national level. Joint monitoring tours and evaluation of
advanced breeding lines is also undertaken. A cowpea network coordinator is
based at Ouagadougou, Burkina Faso with the Scientific Technical and Research
Commission of the Organization of African Unity (OAU), being funded through a
grant from USAID. The coordinator is a member of the Steering Committee for the
cowpea network for West and Central Africa. In addition, Research Liaison
Scientists based at IITA headquarters also assist national programs in developing
their cowpea research work.
IITA recently signed an agreement with the Southern Africa Centre for Cooperation
in Agricultural Research (SACCAR) to locate a team of scientists in Maputo,
Mozambique to give regional support to the countries of the Southern African
Development Coordination Conference (SADCC) for cowpea improvement.
The major objective of IITA's grain legume improvement program, as mentioned in
the IITA Strategic Plan, is to develop varieties that are well adapted to the
cereal-based farming systems of the African savannas and that meet the dual needs
for grain and fodder.
Given this general objective, the main researchable issues for cowpeas in cereal
mixtures include:
1. Their morphological and physiological adaptation to interplanting with
cereals in a range of environments with varying lengths of growing period.
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2. The identification and incorporation of multiple pest and disease resistance
into adapted varieties.
3. The nitrogen economy of the cereal/legume systems in terms of biological
nitrogen fixation.
4. The basis and improvement of drought tolerance in cowpeas, especially for the
millet farming system of the semi-arid zone.
To accomplish IITA's strategy to improve cowpea production in the cereal-based
systems, IITA recently established a research station in Kano. A cowpea breeder
and physiologist based at the station will collaborate with a local institute,
IAR, and Ahmadu Bello University, Samaru and with ICRISAT scientists at Kano for
farming systems research in cereal systems.
Some of the specific research needs include the search for host-plant resistance
to cowpea pests, which will involve three essential strategic components: (1)
the refinement of existing methods and the development of new methods to identify
better sources of resistance, which will require substantial research on the
biology and rearing of the pests; (2) the extensive collection by the IITA
Genetic Resources Unit of new germplasm, especially of wild relatives in Africa,
and the intensive evaluation of both existing and new collections and of breeding
materials; and (3) collaborative basic research with advanced laboratories for
the study of pest biology, wide crosses, resistance mechanisms and innovative
screening methods.
IITA's Interest in Collaborative Research with Advanced Laboratories
1. Biotechnology Research
a. Interspecific hybridization in Vigna. IITA has identified several
sources of resistance to post-flowering pests in Vigna species other than
cowpea, Vigna unguiculata. So far all attempts to cross cowpea with the
resistant Vigna have failed, interspecific hybridization in Vigna
therefore has high priority.
b. Embryo culture and morphogenesis. Embryo abortion before seed maturity
has been consistently observed in some Vigna interspecific crosses.
Therefore methodology needs to be developed for culture media for embryo
rescue or callus culture.
c. Gene transformation. Agrobacterium-mediated transformation systems using
callus and other plant tissues need to be investigated. Further studies
on CPT1 cowpeaa trypsin inhibitor gene) and BT protoxin (Bacillus
thuringiensis) as well as novel transformation systems like DNA particle
gun are warranted.
d. Restriction fragment length polymorphism (RFLP) mapping in cowpea. We
believe that RFLP mapping will greatly help us, in classical cowpea
breeding in the optimization of use and management of cowpea germplasm,
whereby breeders will be able to pinpoint the best accessions for
crossing in the breeding program. In addition, RFLP should also assist
us in determining the range of genetic diversity in the germplasm.
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2. Biotic and abiotic stresses
The main research needs here are in innovative screening methods for
resistance to Striga and post-flowering pests including cowpea storage
beetle, investigation of resistance mechanisms and in identification of
better sources of resistance.
Another area of need we have is in the identification of morphological and
physiological traits for heat and drought tolerance.
A third area of need is in plant microbial interactions, improvement in
biological nitrogen fixation.
3. Socio-economic research
Diagnostic survey of constraints and socio-economic factors underlying cowpea
genetic diversity and cropping systems.
References
International Institute of Tropical Agriculture. 1988. IITA Strategic Plan
1989-2000. Ibadan, Nigeria. 108p.
International Institute of Tropical Agriculture. 1988. IITA Medium-Term Plan
1989-1993. Ibadan, Nigeria. 91p.
Singh, S. R. and Rachie, K. O. 1985. Cowpea research, production and
utilization. Chichester, U.K.: John Wiley & Sons. 460p.
Grain Legume Improvement Program. 1989. Cowpea Research at IITA. Research
Monograph No. 1. 19p.
-76-
Question and Answer Period: Status of Cowpea Research/IITA
Q: What is the update information on thrip resistance?
A: Four or five lines have been identified which have resistance superior to the
lines in the first generation of resistance materials.
Q: Follow-up question on resistance to Maruca.
A: Morphopological characteristics of the plant are very important. Infesta-
tions occur first on the young, tender leaves and shoots with subsequent
infestations moving to hollow plant stems. At this point the insect
functions as a stem borer. Solid stem genotypes are known. This character-
istic is common in wild cowpea accessions. Several changes in plant
architecture have influenced the damage from this insect. The long peducules
of the of the inflorescence in cultivated types are significant and most wild
types have the inflorescence within the leaf canopy which increases the
damage. Also a wider angle between seed pods decreased the likelihood of
insect penetration.
Q: A question was raised relative to the policies for IITA established
sub-programs within national research entities.
A: It is not the policy of IITA to establish funded programs at national
research locations. There are, however, a few exceptions to this where it is
critical to provide a level of expertise not available within the local
program. One person located in Ghana was cited as an example of this special
case. A more likely means of providing support to national programs would be
to provide training and backstopping for teams of local researchers and
thereby increase the capacity of national programs to address critical
national and regional issues.
Q: What is the status of cowpea resistance to aphids?
A: Aphids are a major problem over much of the cowpea growing area of West
Africa. This is true in spite of the existence of high levels of resistance
in varieties adapted to the region. It is not immediately clear why there
has not been a wider acceptance of aphid-resistant materials.
Q: Have regional centers (regional sub-centers of IITA) been phased out?
A: Yes. Cutbacks in funding have forced this action. The case of the regional
center in Brazil was cited. As a result of these actions there has been an
increase in the training of local scientists and increased program
coordination between IITA and national programs.
Q: What type of cowpeas are most frequently grown in Africa; Type I or III?
A: The choice of plant growth habit varies greatly from region to region and by
the ways cowpeas are used in the farmers' cropping cycle. In many cases
cowpeas will be planted following more valuable crops such as corn or
sorghum. It is not uncommon to find these producers selecting Type III
varieties with the objective of maximizing forage production for use as
animal feeds.
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This discussion prompted Dr. James Oxley from the Small Ruminant CRSP to
observe the significance of legume forage as an animal feed supplement during
the dry season. He commented on: (1) the importance of late season
production; (2) the safe storage of plants on root tops; (3) the controlled
feeding of this forage as a supplement; and (4) the importance of this feed
source in the reproductive cycle of animals.
Dr. Singh commented on the various bilateral projects between IITA on forage
quality.
Q: Dr. Singh was asked to comment on post-harvest research in progress at IITA.
A: Numerous research and verification activities are in progress which draw
heavily on practices in use in local communities. This includes the
investigation of storage containers up to and including the use of old
fertilizer bags, the application of oil to coat the seed, and special efforts
that are in use to preserve seed stocks. An attempt is made to make accurate
comparisons between low cost technologies and the technologies which may be
used to protect commercial seed lots stored for food or seed purposes.
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APPLYING A BENEFIT/COST APPROACH OF RATE OF RETURN ANALYSIS
TO SPECIFIC CRSP PROJECTS
Lisa A. Schwartz and James F. Oehmke
Department of Agricultural Economics
Michigan State University
Overview of Evaluation of Investments in Agricultural Research
Recently, the international agricultural development community has demonstrated
increased interest in assessing the returns to agricultural research and exten-
sion. In both host and donor countries, international development research is
currently characterized by tight budgets and skepticism about returns to
agricultural research investments. In the U.S. this financial climate has led to
congressional demands for accountability, thus pressuring donor agencies to take
stock of returns to ongoing projects before moving on to new initiatives. The
World Bank is currently beginning a major study of its twenty-four year support
of the T&V (training and visit) system of extension in developing countries.
A.I.D. is funding a Michigan State University (MSU) study, in the Department of
Agricultural Economics, of the use of rate of return (ROR) analysis of
agricultural research projects in developing countries. This paper presents rate
of return analysis as a tool to be used by researchers and administrators to
facilitate both the allocation of scarce resources to research projects and to
assess the returns to investment in agricultural research.
Daniels et al. (1990) review the literature on returns to research in Africa and
find that quantitative studies are scarce relative to Asia and Latin America.
"To date only four [ROR] studies have been identified for Africa" (Daniels et
al., 1990, p.18). There is clearly a need for additional evaluative work to
provide information for improving project design and implementation and to
generate public sector support for agricultural research.
The latter is important because the products of research often become public
goods after dissemination. That is, one person's use of an innovation, such as
hybrid seed corn, cannot exclude another person from using the innovation.
Furthermore, "Private firms tend to underinvest in many types of agricultural
research from society's point of view because they cannot internalize many of the
benefits from that research" (Norton and Davis, 1981, p.26).
From the perspective of the Collaborative Research Support Programs (CRSPs), ROR
analysis provides an opportunity to evaluate and to strengthen their projects
where appropriate. To this end, it is useful to generate capacity for in-house
quantitative evaluation of the returns to CRSP research. This paper,
which suggests guidelines for such an effort, offers a practical approach for
carrying out an impact study for any given CRSP project.
Background of ROR Analysis
The first study of returns to agricultural research at a commodity level was
carried out by Griliches in 1958. He calculated "the loss in net social sur-
plus . [a measure of national welfare] . that would occur if hybrid corn
were to disappear" (Norton and Davis, 1981, p.27). In his 1964 paper on the
benefits of research expenditures and education of the farm labor force Griliches
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concluded that such "expenditures affect the level of agricultural output
significantly and that their social rate of return is quite high" (p.961).
"Return" refers to the benefits which accrue: (1) to producers in the form of
lower per unit costs of production and (2) to consumers in the form of lower
purchasing prices for commodities.
There are various different methods used to estimate the benefits and costs which
go into the calculation of the ROR. One method, developed by Schultz (1953), is
to estimate the net benefits and costs associated with development and
dissemination of a particular innovationss. The benefit/cost approach yields
the average annual rate of return generated by the resources invested in
research. This is the approach outlined in this paper.1
There are other methods which separate the returns to different components of a
research project. .For example, the production function approach separates the
effect of research from education, supply of conventional inputs or research in
another geographical area (Norton and Davis, 1981). It entails the derivation of
a production function including research as a variable which is then used to
generate a marginal rate of return. The production function approach, first used
by Griliches in 1964, requires relatively complex calculations and specific data
on inputs to the production process in order to build a representative production
function.
Different methods of assessing the returns to agricultural research require
"different kinds of expertise and resources, especially management time; they
themselves are subject to . [and have an impact on] . benefit/cost
considerations"-(Contant and Bottomley, 1989, p.1). Regardless of the ROR
analysis method chosen, to avoid misleading results project evaluators must
recognize that economic policies affecting relative prices of both farm inputs
and output, subsidies and exchange rates all have an effect on the returns to
agricultural research.
What is a Rate of Return?
Rate of return analysis utilizing a benefit/cost approach is a user-friendly
method of assessing the returns to agricultural research projects. The concept
behind the ROR is that a given investment will yield some return in the future.
However, a dollar earned in the future is worth less than a dollar earned today.
The ROR methodology collapses the time stream of current and future research
benefits into a single measure which is easily compared to a minimum acceptable
rate of return. An acceptable rate of return is based on the cost of funding; in
developed countries this number is close to 10 percent. An acceptable ROR in
developing countries may be higher due to inflation.
The method of calculating the rate of return using the benefit/cost approach has
three components. First, the stream of benefits associated with a specific
project is estimated.2 Second, the stream of costs incurred by the project and
supporting activities is estimated. Third, the estimated benefits and costs are
1For a more complete discussion of the origins of this method, see Daniels et al.
(1990) and Norton and Davis (1981).
2The stream of benefits refers to benefits over time.
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plugged into the ROR formula to determine the estimated ROR. The estimated ROR
"is the maximum interest that a project could pay for the resources used if the
project is to recover its investment and operating costs and still break even"
(Gittinger, 1982, p.329). Suggestions for carrying out the first and second
components are discussed in the remainder of this paper. For details of the third
component see the Appendix.
It is possible to use the ROR technique either prior to (ex ante) or after (ex
post) a project has been implemented. For example, the benefit/cost approach to
rate of return analysis can be used for rapid appraisal of actual project
returns. Such an ex post evaluation was done in the CRSP Senegal impact study.
The study was prepared over a period of five months using secondary data from
annual reports and price data sent over a modem transfer from Senegal. Given
that resources for agricultural research are relatively scarce, budget requests
from research organizations can be strengthened by the inclusion of ROR estimates.
Limitations of the Benefit/Cost Approach
The rate of return as an indicator is sensitive to the estimation of benefits and
costs. If the evaluator errs in assessing the benefits and costs then she will
incorrectly calculate the ROR. One way to approach this task is to examine
variability in rates of return under different assumptions about benefits and
costs--this is called sensitivity analysis. Additionally, the method of ROR
analysis chosen affects the interpretation of the ROR. The rate of return
calculated using aggregate benefits and costs approach does not separate out
returns to each component of the project individually. However, this method has
the advantage of being relatively easy to implement and provides an evaluation of
project performance in terms of economic and/or financial benefits. In order to
get rates of return to individual components, the aggregate net benefits must be
broken down into the benefits and costs attributable to each component.
Implementing the Benefit/Cost Approach and Tailoring it to Specific Projects
There are six steps in the process: (1) identify the key innovations and their
context; (2) identify potential economic benefits and costs associated with those
innovations; (3) develop an analytical framework; (4) collect data; (5) quantify
benefits and costs; (6) calculate the rate of return; (7) conduct sensitivity
analysis.
The first stage of an impact study is to identify the key factors which are being
addressed by a given research project. In the case of the CRSP Senegal project
the innovation being developed was improved cowpea varieties which, among other
characteristics, have an early harvest, improved yields, resistance to drought
and disease, and delayed senescence. These varieties were being developed for
growth in a semi-arid climate under rain-fed agriculture where drought has been a
major problem. All of these conditions were important factors related to the
estimation of economic costs and benefits necessary for calculating the rate of
return.
Identification of key innovations:
This first step of the process requires research goals to be broken down into
specific categories. Listed below are generalized key question areas which can
be used to identify relevant characteristics for consideration.
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1. Seasonal factors such as length of growing season, livestock or fish
production cycle, rainfed versus irrigated production and variability in food
stocks.
2. Geographical factors including rainfall, elevation, slope and diversity of
areas covered. Examples of additional questions are: (a) Is the
innovations) appropriate for diverse areas or only in a specific region?
(b) In the location of planned dissemination, are prices high enough to
ensure returns to the investment?
3. Quality factors such as the effect of new seed varieties on the taste,
caloric content and nutritive value of foods, thereby improving human health;
better animal health leading to improved quality of livestock.
4. Environmental factors such as soil conservation and decreased use of
chemicals.
5. Effects on transportation and storage such as resistance to storage pests or
rotting.
6. Marketing, processing and infrastructural development directly related to the
research project.
7. Training of staff: on-the-job, degree programs, short courses.
8. Effects on the institution building process such as increased research
capacity due to infrastructural improvements and improved human capital.
9. Extension component including all dissemination activities such as radio
programs, field agents, written materials, etc.
Once the relevant elements of a research project have been identified in terms of
its goals and the conditions under which it functions, it is possible to proceed
with the second step--identification of economic benefits and costs.3
Costs:
Costs are relatively easy to assess compared to benefits. The key is to identify
all expenditures (both monetary and in-kind) associated with a given project.
1. Annual Research Costs such as capital, land and labor costs, personnel
charges for professional and technical staff and cost of materials.
2. Duration of research (in years) is important. The length of a project is a
function of:
complexity of the research itself: research programs which are very
complex may incur higher costs because a longer period elapses before
benefits are earned from increased production.
3The list of benefits and costs was developed based on Contant and Bottomley
(1989) and Gittinger (1982) with additions.
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linkages to foreign research and existing domestic research programs may
speed up the research project by sharing research results and the burden
of funding.
suitability and motivation of research staff (qualifications, areas of
specialization, experience, incentives).
physical research capacity.
size and consistency of funding.
3. Costs of dissemination such as extension and the establishment of input
supply channels.
4. If the new technology is costly to use, adoption and the rate of increased
benefits will be slower. This is a function of:
financial costs to producers (are they higher with the innovations] and by
how much?)
exchange rates which affect imported inputs
labor requirements: in terms of hours and degree of skill required
subsidies or taxes on inputs.
Benefits:
Benefits can be either tangible or intangible. Tangible benefits such as
increased yields or livestock production or decreased storage losses are
relatively easy to identify and to measure if data are available. Intangible
benefits include such things as improved health, longer life, more and better job
opportunities, feelings of national pride, etc. Intangible benefits may be
difficult to identify and sometimes impossible to put a value on, but they should
nonetheless be discussed in an impact assessment of a research program. In the
Senegal impact study benefits such as improved household food security and food
quality were discussed in detail although not included in the ROR analysis due to
lack of data
1. Benefits related to production:
gross benefits (increased revenues from increased production) to producers
and consumers (increased supply and lower prices)
increased foreign exchange earnings or savings
level of price supports or price controls and taxes on production which
affect earnings
decreases in yield variability and/or price risk
effects on equity (gains to poor vs. rich farmers)
effects on food security in terms of availability and access to food
additional processing opportunities.
2. The ceiling on adoption or the maximum number of potential adopters:
Adoption may be 100 percent, as it was with hybrid corn in the U.S., or far
less. The adoption ceiling is particularly important when considering
potential benefits prior to implementation of a research project. Factors
affecting this element are similar to those considered when estimating costs
of adoption:
farmers' access to funds for any initial investment
geographical and infrastructural constraints
education levels and age of target population
willingness to bear risk.
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3. Length of time prior to reaching the adoption ceiling is a function of:
degree of "coordination between input suppliers, research, extension and
output markets" affects the rate of adoption of an innovations) and thus
the success of any given research project (Echeverria and Oehmke, 1990).
This factor influences the availability, appropriateness and timeliness
of credit and other inputs.
additional net financial benefits (gross benefits minus costs)
changes in required expenditures
technical ease or difficulty of implementation
changes in yield variability and/or price risk
farmer receptiveness to innovation and the tendency to adopt innovations
in a stepwise manner rather than as a whole package
population pressure.
4. The longer an innovation will survive in a production system the greater the
benefits society can derive from it. The lifespan of an innovation is
affected by:
genetic and other elements of stability in the innovation
probability of displacement by further innovation
rate of pathogen mutation.
5. Benefits to human capital development can be measured in terms of monetary
and non-monetary returns. The following are some factors to consider:
number of people trained
change in salary following education
decrease in number of foreign scientists required
changes in lifestyle--can be measured by surveying degree holders
concerning changes in housing, leisure time, etc.
6. Intangible and indirect benefits should be listed to clarify the full effects
of the research.
Data Collection Requirements
At this point of the analysis the costs and benefits have been identified but not
quantified. Before moving on to steps three through six it is useful to discuss
the data requirements of rate of return analysis. Quantitative techniques are
only as good as the quality of data fed into them. Availability of data in
developing countries is frequently a major constraint to the use of more precise
evaluation techniques. However, the minimum data requirements for the average
rate of return approach are relatively few compared to other methods. The actual
data collection process should follow the identification of specific benefits and
costs to be estimated and the development of an analysis framework to avoid
wasting time collecting unnecessary data. Several considerations must be made
prior to data collection such as how is it be collected, from where and by whom.
Specific types of data required for estimating tangible benefits include: prices
for relevant commodities, both traditional and innovative (different seed
varieties, animal breeds), yields (with and without) the innovation of plants,
fish or number of animals, and area devoted to both new and traditional
varieties, methods and practices.
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To estimate costs, all expenditures contributing to the project, both in cash and
in-kind, should be tallied. Investments in extension and research could be added
up separately to distinguish between expenditures on technology generation versus
transfer. Prices for traditional inputs are needed as well as costs of
supporting services.
The CRSP Senegal study used secondary data from annual reports and articles as
well as price data sent electronically (via modem) from ISRA (Senegalese Institute
of Agricultural Research) in Senegal. The relatively easy access to price data
made possible by the modem illustrates the importance of maintaining even a basic
computerized and coordinated data base. Individual projects must decide what is
the best method to facilitate ongoing evaluation and information transfer both
inside an individual research institution and between institutions. To this end
projects should establish consistent methods of data storage and selection of
hardware and software in order to develop compatibility of data systems across
projects, thus building a CRSP data base.
There are two main advantages to establishing a CRSP data base: (1) data would
be available in a convenient form for comparative analyses of projects within one
CRSP or characteristics of projects across CRSPs; and (2) the large sample of
research projects available for benefit/cost analysis would allow improved in-
sight into how different factors will affect research under diverse conditions.
Of course, the benefits and costs of establishing such a data base should be
estimated before implementation.
Analysis of Data
The third, fourth and fifth steps in the overall assessment process are to set up
a framework for data analysis, collect the data and specifically quantify costs
and benefits for the project. This analysis of data is done in order to
calculate the rate of return-step six.
The process of quantifying benefits and costs involves the aggregation of data to
determine net benefits. For example, the value of benefits arising from adoption
of a new seed variety are assessed by calculating the area devoted to the variety
and multiplying that number by the yield and their price which the variety is
expected to earn, thus yielding gross returns. The costs of adoption then
"consist of the costs of growing the new variety (extra fertilizer, labor, other
inputs as well as the cost of improvements in services) minus the costs of
growing the old variety, or other commodity previously produced on the same land"
(Contant and Bottomley, 1989, p.27). The gross benefits minus the costs equal
net benefits.
A technique for clarifying the process of quantifying costs and benefits is to
set up a word equation which clearly delineates the changes resulting from the
introduction of an innovation.4 The following example was developed based on the
CRSP Senegal impact study (Schwartz et al., 1990).
(1) Changes which increase benefits
[hectares planted to improved cowpeas x yield x price] [input costs] =
gross benefits
4This format used for the "word equation" is actually a partial budget.
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(2) Changes which decrease benefits
[hectares planted traditionally to peanuts x yield x price] + [hectares
planted traditionally to cowpeas (old varieties) x yield x price] -
[traditional input costs] = opportunity cost of land
(1) (2) = (3) net benefit of production changes
(4) Costs of research and technology transfer
(3) (4) = (5) net benefit to all investments in cowpea research and "operation
cowpea"
There are other benefits to the CRSP Senegal project which were discussed in the
impact study but not included in the calculation of the rate of return due to a
lack of specific data. A key element not included is the caloric and nutritional
contributions of cowpeas to the diets of people in Northern Senegal. There simply
were not enough data available on household consumption to include these benefits
in the calculation. However, when such data are available they can be included.5
An additional technique for establishing an analysis framework is to set up a
table with the benefits and costs and discount rates shown clearly. Data are
collected based on what is needed to fill in the table. Tables can be modified
relatively easily to suit availability of data. For the sixth step the data is
entered into a suitable software program, such as LOTUS 1-2-3 or MSTAT, and the
ROR is calculated.
Finally the seventh step, sensitivity analysis, is used in order to estimate the
relative returns to investments in a research project under conditions different
from those originally considered: higher or lower prices, yields, etc. As
Evenson points out, it is necessary to "make some assumptions regarding the
continuation of the benefit stream beyond the period of analysis" (Evenson, 1988,
p.52). Sensitivity analysis is useful for approximating the effect of changes in
key variables over time. Sensitivity analysis requires recalculation of
benefits, costs and rates of return under different scenarios which may reflect
actual situations.
For example, benefits will be different if an increase in yield is attributable
100 percent to research versus 50 percent to research and 50 percent to increased
rainfall.
Application to the CRSP Senegal Impact Study
In the CRSP Senegal study there were two major elements of the project around
which questions were structured. First, food security and seasonal fluctuations
in food supply were considered. The factors affecting food security were identi-
fied as seasonal variations in prices and yields; variation in price across
markets and geographical variation in price; and changes in the quality of food
produced. The Senegal study used average prices from several varieties of
cowpeas but focused on one region (Louga).
The Senegal study compared the possible combinations of benefits accruing from
new innovations under differing conditions and in different seasons. It looked
at how cowpeas can provide green pods for food during the period of the hungry
season and early grain before the main harvest. Additionally, cowpeas can be
planted in drought years when alternative crops such as peanuts failed entirely.
5In the case of a nutrition research project, household consumption data with and
without research innovations will be the primary input into the ROR calculation.
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The second major element included in the assessment of costs and benefits was the
scientific training component. It was quantitatively analyzed based on the cost
of education versus the cost of importing expertise and returns to training in
terms of monetary and non-monetary benefits.
The benefits and costs from both research and training were entered into tables
and the rate of return computed to be 63 percent, sensitivity analysis indicated
that this rate of return did not change much even when the assumptions concerning
benefits and costs were varied somewhat (see Schwartz et al. for details).6 One
reason for the high rate of return was the important function that short-cycle
cowpeas served in the farming system of providing food during the hungry season.
The benefits from the innovation represented a change from zero food under low
rainfall conditions.
Conclusion
Some ROR calculations can be very complex, however the relatively simple
benefit/cost approach to calculating a rate of return is user friendly in that it
has minimal data requirements and can be carried out with easily accessible
software such as LOTUS 1-2-3. It should be recognized that to use more
complicated methods is more costly but it is also more accurate and informative.
However, there is no universally perfect method for assessing returns to research
and there are clear advantages to a user friendly approach with relatively
limited data, funding and time requirements. The key reason for using
quantitative methods for analyzing costs and benefits and calculating rates of
return, based on estimates or actual data, is to assess the viability of proposed
research or the value of disseminated innovations in terms of their contribution
to social welfare based on economic measures.
Levels of acceptable rates of return are typically established by donor
organizations funding research projects-A.I.D. uses a rate of approximately 11
percent, the World Bank uses a range of 8 percent -15 percent.7 In considering
the value of a project there are often benefits which are difficult to quantify
for reasons of lack of data and/or theoretical framework. However, these
elements should not be ignored. Useful impact studies must include a clear
explanation of both quantifiable and non-quantifiable benefits if they are
properly to assess net social benefits of research.
This paper provides an introduction to using the benefit/cost approach of rate of
return analysis and provides a framework for carrying out an impact study using
the ROR method. Additional resources required for the actual implementation of
such a study are a computer or programmable calculator (plus manual) and some
additional technical references.
6The GAUSS software package was used.
7These rates are based on the assumed opportunity cost of capital or the return
to the next best alternative investment. As it is difficult to know the actual
opportunity cost of capital, acceptable minimum rates of return are based on the
cost of funding.
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References
Contant, Rudolph B. and Anthony Bottomley. 1989. Manual for Methods of Priority
Setting in Agricultural Research and Their Application. The Netherlands: ISNAR.
CIMMYT. 1987. From Agronomic Data to Farmer Recommendations. El Batan, Mexico:
CIMMYT.
Daniels, Lisa, Julie Howard, Mywish Maredia, James F. Oehmke and Richard Bernsten.
1990. Assessment of Agricultural Research: Ex-Post, Ex-Ante, and Needed
Methodologies. East Lansing, Michigan: Michigan State University.
Evenson, Robert E. 1988. Human Capital and Agricultural Productivity Change,
Proceedings of the International Conference of Agricultural Economists. IAAE.
Beunos Aires, August 24-31,
Gittinger, J. Price. 1982. Economic Analysis of Agricultural Projects, 2nd edition.
Baltimore: Johns Hopkins University.
Griliches, Zvi. 1964. Research Expenditures, Education, and the Aggregate Agricul-
tural Production Function. The American Economic Review LIV(6):961 -974.
Norton, George W. and Jeffrey B. Davis. 1981. Evaluating Returns to Agricultural
Research: A Review. American Journal of Agricultural Economics 63:685-699.
Ruben G Echeverria and Oehmke, James F. 1990. Sequential Evaluation of Agricultural
Research, Staff Note No.90-83. Netherlands: ISNAR.
Schultz, T.W. 1953. The Economic Organization of Agriculture. New York:
McGraw-Hill.
Schwartz, Lisa A., James A. Sterns and James F. Oehmke. 1990. Impact Study of the
Bean/Cowpea CRSP for Senegal. East Lansing, Michigan: Michigan State University.
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APPENDIX
The equation used to calculate the rate of return looks like this:
n
E t Ct = o
t=0 (1 + r)t
To compute the IRR, solve for r. E indicates a summation from the beginning of
the project to some future point in time (n = # of years); (B) (C) represents
the difference between benefits and costs; and (1+r)t serves to discount the
stream of net benefits over time where t = time and r = the rate of return which
makes the above equality hold.8
When aggregating the time stream of net benefits, weights can be used to
attribute greater importance to returns to research which directly improve the
welfare of targeted groups. For example, it may be appropriate to attach heavier
weights to benefits to poorer farmers in order to take account of a desire to
favor those research projects which are likely to benefit the poor (Contant and
Bottomley, 1989, p.23).
8r equals the rate at which the present value of benefits equals the present
value of costs. At this point, the rate of return indicates that a project is
earning returns equal to the next best alternative investment.
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OVERVIEW OF BEAN RESEARCH ACTIVITIES
G. S. Abawi and N. F. Weeden
Departments of Plant Pathology and Horticulture Sciences
Cornell University
The bean pathology projects have been a major component of the research program
directed by George Abawi since 1972. Detailed studies have been conducted on the
biology and epidemiology of several fungal and nematodal diseases of beans. The
overall objective of the program is the development of integrated control measures
that are effective and economical, and contribute minimally to environmental
pollution. Fungal diseases investigated included web blight, white mold, Alter-
naria pod-flecking, Fusarium wilt, charcoal rot, and root-rots incited by species
of Rhizoctonia, Fusarium, Thielaviopsis and Pythium. Nematode diseases of beans
which were studied were those caused by the root-knot and lesion nematodes.
Recently, bean research projects have emphasized the impact of cultural practices
on disease severity, development of germplasm screening procedures, and the
identification of sources of resistance to a number of bean pathogens. In
cooperation with CIAT scientists and with the contribution of thesis research by
two Ph.D. graduate students, several sources of bean germplasm with resistance to
Thanatephorus cucumeris and its anamorph Rhizoctonia solani, Macrophomina
phaseolina, Fusarium oxysporum f. sp. phaseoli and Meloidogyne spp. (root-knot
nematodes) have been identified. Current research efforts include characterizing
the identified resistance factors, elucidating their inheritance, determining the
races of Fusarium wilt pathogen that exist in Latin America, investigating the
role of root-knot nematodes in modifying the reaction of Fusarium wilt
susceptible and resistant bean cultivars, and biological control of selected
fungal and nematodal bean pathogens.
The research program being directed by Norman Weeden has a strong commitment to
the genetics, genetic diversity, and systematics of Phaseolus and related genera.
Allozyme polymorphism has been used to distinguish cultivars of white seeded
beans and to establish genetic markers and linkages in the common bean. Several
studies are currently being performed in Weeden's laboratory, including a survey
of allozyme and chloroplast DNA polymorphism in African Vigna, RFLP mapping of
the Phaseolus genome, analysis of the glucosephosphate isomerase genes in
Phaseolus, and a search for genetic markers for several commercially important
characters (resistance to Macrophomina, photoperiod genes, etc.). A relatively
low variability was found among the cultivars of cowpea, but high levels of
variability was found in the closely related taxa examined including the other
subspecies of Vigna unguiculata.
The above mentioned bean research programs are only part of the overall bean
research being conducted by several faculty in Plant Pathology, Horticultural
Sciences, Entomology, Plant Breeding, and Vegetable Crops at Cornell on the
Geneva and Ithaca campuses.
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RESEARCH INTERESTS
Paul Gepts
Department of Agronomy and Range Science
University of California-Davis
The overall, long-term goal of my program is to investigate the genetics of bean
species in the Phaseolus-Vigna complex. This research orientation combines both
basic and applied research as well as field and laboratory experimentation and is
intended to provide both genetic information and genetic materials to the
California bean breeding program in collaboration with Dr. S. Temple. Currently,
the activities of my program are organized along three research orientations:
Organization of genetic diversity in bean species:
I seek to determine how to characterize and where to find genetic diversity in
the primary gene pools of principally common bean (Phaseolus vulgaris), but also
tepary bean (P. acutifolius), runner bean (P. coccineus), lima bean (P. lunatus)
and cowpea (Vigna unguiculata). Analyses of molecular markers such as seed
proteins and allozymes reveal that, in all species, domestications appear to have
induced a genetic bottleneck at the molecular level, indicating that wild
ancestors may contain a significant store of additional variability not
represented among cultivars. In certain species, cultigens resulted from
multiple domestications (P. acutifolius, V. unguiculata). The multiple
domestication finding is particularly significant in that both common and lima
bean cultivars belong to two evolutionary divergent components of their primary
gene pool (Mesoamerican vs. Andean). Results from common bean indicate that this
divergence includes not only molecular markers, but also morphological traits
(e.g., growth habit), and agronomic traits (e.g., disease resistance). Further
analyses, in collaboration with Dr. S. Singh at CIAT, have shown that it is
possible to divide the Mesoamerican and Andean components into smaller groups on
the basis of phaseolin type, allozymes, morphological traits and agronomic
characters (e.g., disease resistance, phenology, adaptation). Identification of
these groups will help in establishing core collection within the Phaseolus
vulgaris gene banks and help breeders select parents for crosses.
Current projects in this area include: (1) identification of hypervariable DNA
markers for population genetic studies; (2) molecular evolution of phaseolin in
P. vulgaris, P. lunatus, and V. unguiculata; (3) segregation and linkage in inter-
gene pool crosses within P. vulgaris; (4) genetics of morphological and photo-
period differences between wild and cultivated P. vulgaris; and (5) diversity of
cpDNA and nuclear DNA sequences in P. coccineus.
Mapping of the common bean genome:
My objective is to establish a linkage map of the common bean genome that
integrates molecular markers (principally RFLPs) and agronomic traits, including
growth habit and other morphological differences distinguishing wild and
cultivated types, earliness, drought and low soil phosphorus tolerance, and
disease resistance (BCMV: I, anthracnose, angular leafspot, rust, and common
bacterial blight). In collaboration with Dr. S. Singh (CIAT), four recombinant
inbred population (RIPs) have been established that segregate for the traits
mentioned. The advantage of RIPs is that they allow both quantitative and
qualitative traits to be analyzed and the data can be accumulated on the same
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