Agronomy Research Report: AY-91-02
RELATIONSHIPS BETWEEN RATES OF NEMATICIDE AND LEAF NUTRITION
OF TWO SOYBEAN CULTIVARS IN NEMATODE INFESTED SOIL
Serge Edme', R.N. Gallaher', R. McSorley2, and D.W. Dickson2,
'Graduate Student and Professor of Agronomy and 2 rofessors
of Nematology, respectively, Inst. of Food tialnr ci.,
Univ. of Florida, Gainesville 32611. L i8a
NOV 1 01991
ABSTRACT University of Florida
Crop varieties and nematicides are known to signifTicnflTy
affect plant nutrition and crop yield. The effects of aldicarb
(nematicide) at four rates (0, 0.56, 0.84, 1.12 kg a.i. ha1')
on the leaf element composition were tested on two soybean
[Glycine max (L.) Merrill] cultivars ('Leflore' and 'Davis').
A factorial experiment in a randomized complete block design
with 4 replications was used to analyze leaves at the R2 stage
for N and minerals. Soybean cultivar was in general more
important (p<0.01) than the levels of nematicide. Leflore
accumulated significantly more N (4.7 g kg1), P (0.64 g kg'-),
K (3.02 g kg'1), Mn (50.44 mg kg'1), and Zn (20.06 mg kg-) in
its leaves than Davis which had more Ca (1.03 g kg-1), Mg (0.96
g kg-1), and Cu (0.94 mg kg-1). The leaf P, Ca, Mn and Zn
concentrations were sufficient for plant growth in both
cultivars, whereas Davis was deficient in N, Leflore in Mg,
and both varieties in K and Cu. Nematicide rates were much
less important (p<0.05), only affecting the concentrations of
N, P, and Mg. Applying aldicarb at 0.56 kg a.i. ha-'
significantly increased the leaf N concentrations by 4.7 g kg"
I, whereas Mg appeared to be reduced by its application. A
variety-dosage interaction was obtained for leaf P: Leflore
was superior to Davis at all nematicide rates, except at the
0.56 kg, whereas 0.56 kg a.i. of aldicarb had a larger effect
(0.71 g/kg) than the 0-level only within Davis. Nematicide
applications tended to decrease leaf P concentrations in
Leflore leaves. Differences in soil K and Ca concentrations
were only observed among the two soybean cultivars. Davis,
which was stunted from nematode damage extracted less K than
Leflore, which in turn extracted less Ca than Davis. The soil
pH was significantly lower in the experimental units with
Davis (5.92) than in those with Leflore (6.09). Nematicide
rates produced no change in the soil element concentrations.
INTRODUCTION
Plant-parasitic nematodes can cause extensive damage to
field crops, including soybean [(Glycine max (L.) Merrill].
Many studies have shown positive yield response to application
of nematicides (Kinloch, 1974; Minton et al., 1979; Townshend,
1990; Rhoades, 1980). In soil infested with root-knot
[Meloidogyne incognita (Kofoid & White) Chitwood] or root-
lesion nematodes [Pratylenchus brachvurus (Godfrey) Filipjev
& Schuurmans-Steckhoven and P. zeae (Graham)], nematicide
applications prior to or at planting soybean are essential to
produce vigorous and healthy plants.
Nematodes are a serious problem in Florida for soybean,
particularly in warm sandy soils (Dickson and McSorley, 1991).
Root-knot nematodes of the genus Meloidogyne [M. incognita, M.
arenaria, and M. -avanica (Treub) Chitwood], the soybean cyst
nematode (Heterodera glycines Ichonohe) and the sting nematode
(Belonolaimus longicaudatus Rau) are reported to be the most
damaging nematodes to soybean in Florida (Kinloch, 1974).
Dickson and McSorley (1991) found cultivar differences in seed
yield between two soybean cultivars (Leflore and Davis, in
favor of Leflore). Davis yield was suppressed by M. incognita
in spite of nematicide application, but no nematode or
nematicide effects occurred on Leflore.
The choice of crops in sequential cropping systems
strongly influences plant-parasitic nematode population
densities (Dunn, 1980). For most effective use, a nematicide
can be used in combination with a multiple cropping sequence
which reduces population densities. Soybean following
vegetables is highly susceptible to root-knot, sting, or
stubby root nematodes, all of which are widespread in Florida
(Dunn, 1980). Certain levels of nematode populations can even
cause extensive injury to young seedlings of resistant soybean
cultivars (Dunn, 1980) and no soybean varieties are immune.
Besides crop rotation and resistance, nematicides are the most
effective means of control. Consequently, the use of an
effective nematicide is often needed for successful soybean
production.
Plant Injury by Nematodes
Nematodes are known to be responsible for stunting,
chlorosis, deficiency symptoms (foliage yellowing),
defoliation, premature wilting, necrosis,, and death of soybean
plants (Perry, 1969). Nematodes can suppress yields
appreciably. Different species of nematodes attack different
parts of the roots and so induce different changes in element
composition of a plant tissue (Kirkpatrick et al., 1964).
Plant-parasitic nematodes have varying degrees of specificity
for certain root regions and for tissues and cells within a
root.
Root destruction and cells damaged by nematodes suggest
a disturbance in the elemental uptake, plant nutrient
composition and growth. This is due to a less efficient
utilization of soil moisture and nutrients by the plants.
Xiphinema americanum Cobb has been associated with extensive
root necrosis, destruction of feeder roots, and top dieback on
a number of crops (Christie, 1952). Reductions in leaf K
concentrations without significant changes in leaf Ca, Mg, and
Na concentrations occurred in sour cherry trees (Prunus
cerasus L.) (Kirkpatrick et al., 1959). Christie and Perry
(1959) reported Fe deficiency on affected corn (Zea mays L.)
and strawberry (Fragaria chiloensis L.) plants, but no
nutritional disorder in non-infected plants. Maung and Jenkins
(1959) found stunted root and top growth but no effect on the
element concentration from infections by Paratrichodorus
christei (Allen) Siddiqi.
The effects of Meloidogyne spp. and Heterodera spp. on
plant element composition have also been reported. Meloidogyne
spp. decreased the element concentrations in lima beans
(Phaseolus lunatus L.) (Oteifa and Elgindi, 1962) and on
tomato (Lycopersicon esculentum Mill.) plant tops (Bird and
Brownell, 1961) or produced no change (Hunter, 1958; Maung and
Jenkins, 1959). These studies indicated a constriction to the
movement of P, N, and K from points of root uptake to other
plant tissues. The effect of Heterodera clycines on plant
nutritional status showed a tendency in reductions of N, P, K,
Ca, and Mg concentrations in soybeans roots and tops
(Ichinohe, 1961), sometimes to deficiency levels.
Several nematode species have been found to affect
element concentrations in plant tissues. Martin and Bingham
(1954) observed significant decreases in avocado (Persea
americana Mill.) leaf concentrations of Mn, Zn, and Cu in all
soils inoculated with Tylenchulus semipenetrans Cobb. Levels
of P, Ca, Mg, K, Fe, S, and B were not affected by these
nematodes. Shands and Crittenden (1957) found that moderate to
high levels of N or K favored the penetration of M. incognita
acrita and the number of galls produced in soybean roots. The
addition of inorganic N increased N concentrations in the
tissues or alleviated the N-deficiency symptoms in soybean
affected by H. glycines (Ichinohe, 1961).
On soybean, previous studies have dealt primarily with
the evaluation of nematode control on yield or growth by means
of nematicides (Rhoades, 1980; Townshend,, 1990; Sasser et al.,
1975) or short-term rotations (Kinloch, 1974; Elliott et al.,
1986). Detailed studies on the effect of parasitic nematodes
on plant nutritional status are very scarce. Kirkpatrick et
al. (1964) indicated that in many cases deficiencies of an
element may be corrected by applications of a readily
available source of the element to the plant, even though soil
analysis data may indicate an adequate supply.
Information on the relation of element composition of
soybean and the application of nematicides is therefore
important. The objectives of this investigation were: 1) to
determine the crop-nutrition-nematicide relationships for
soybean grown in nematode infested soil treated with
nematicides; 2) to study the extent to which changes in the
mineral content of soybean leaf tissue relate to the rate of
the nematicide; 3) to evaluate the efficacy of aldicarb used
at low rates on plant nutrient uptake; and 4) to compare the
mineral uptake of two soybean cultivars.
MATERIALS AND METHODS
The soybean experiment was conducted on the Agronomy Farm
of the University of Florida, Gainesville, Florida, in 1990.
The area is dominated by Grossarenic and Arenic Paleudults
soil types (Soil Survey Staff, 1984). Two soybean cultivars
('Leflore' and 'Davis') were planted 21-22 May and four rates
(0, 0.56, 0.84, and 1.12 kg a.i. ha-1) of the nonvolatile
nematicide aldicarb [2-methyl-2(methylthio) (propionaldehyde
0-(methylcarbomoyl)oxime] were investigated. Four replications
of a 2 x 4 factorial experiment in a randomized complete block
design (RCBD) were sampled for plant leaf and soil nutrient
relationships.
On 14 August 1990 15 upper mature leaf samples of soybean
at the R2 stage (Fehr and Caviness, 1977) were taken at random
from each plot. These samples were dried at 700 C in a forced
air oven and then were ground in a Wiley mill to pass through
a 2-mm stainless steel screen. A subsample was stored in
sterile, air-tight plastic bags for subsequent N and mineral
analyses. Soil samples were also taken from the rows of the
soybean plots for determination of soil fertility.
Plant N Analysis
A mixture of 100 mg dried plant sample, 3.2 g salt-
catalyst (9:1 K2S04:CuSO4), two glass beads, and 10 ml of H2SO4
was vortexed in a 100-ml Pyrex test-tube under a hood. To
reduce frothing, 2 ml of 30% H202 was added in small increments
and tubes were digested in an aluminum block digester at 3700
C for 210 minutes (Gallaher, 1975). Tubes were capped with
small funnels which allowed for evolving gases to escape,
while preserving refluxing action. Cool digested solutions
were vortexed with approximately 50 ml of deionized water,
allowed to cool to room temperature, brought to 75 ml volume,
transferred to square Nalgene storage bottles (glass beads
were filtered out), sealed, mixed and stored.
Nitrogen trapped as NH4SO4, was analyzed on a Technicon
Autoanalyzer II system (manifold, colorimeter) linked to an
Automatic Technicon Sampler IV (solution sampler) and an
Alpkem Corporation Proportioning Pump III. A plant standard
with a long history of recorded N concentration values was
subjected to the same procedure and used as a check.
Plant Mineral Analysis
A 1.0 g sample was weighed into 50-ml pyrex beakers,
placed in a muffle furnace at 4800 C and ashed for a minimum
of 4 hours. Cool beakers containing ashed samples were
carefully transferred to a laboratory hood. Ash was carefully
saturated with 10 ml deionized H20; 2 ml of concentrated HC1
was added and gently boiled to dryness on a hot plate.
This digest procedure results in precipitation of
excessive soluble Si which can interfere with the analysis of
other elements. This water/acid ratio was again added and
brought to a gentle boil on the hot plate and removed so that
dried residue would be in solution. After solutions were
cooled to room temperature they were brought to 100 ml volume,
giving a solution strength of 0.1 N HCl. Solutions were
analyzed for P by colorimetry, K by flame emission and Ca, Mg,
Cu, Fe, Mn and Zn by atomic absorption spectrophotometry.
Soil N Analysis
The procedure was identical to plant analysis, except
that 2.0 g of soil sample was used without glass beads. Soil
particles served the same purpose as boiling beads. The
laboratory plant control sample was also used as a check.
Soil Mineral. pH, and Organic Matter Analysis
Soil samples were extracted by a double acid procedure
(Mehlich, 1953) and analyzed for P, K, Ca, Mg, Fe, Mn and Zn
as described for plant mineral analysis. Soil pH was
determined with a 1:2 soil solution ratio in H20 using a glass
electrode. Soil organic matter (OM) was determined by a
modified version of the Walkley Black method (Walkley, 1947;
Allison, 1965).
Statistical Analysis
An analysis of variance was performed to evaluate the
effect of nematicide rates and soybean cultivars on the
element concentrations of soybean leaves. Statistical analyses
were performed according to a factorial in a randomized
complete block design. Differences in treatment means were
detected by Duncan's Multiple Range Test (DMRT) for comparison
between soybean cultivars, and by polynomial contrasts for
comparison among the four rates of the nematicide. SAS
procedures and programs were applied for all calculations
(SAS, 1988).
RESULTS AND DISCUSSION
Varietal and nematicide effects on the leaf element
composition of two soybean varieties.
Data on the nutrient-element concentrations in the leaves
of the two soybean cultivars and in the soil are expressed in
Appendix 1 and Appendix 2. Leaf N, P, K, Ca, Mg concentrations
were expressed as g kg-' dry material, whereas leaf Cu, Mn, Fe,
Zn concentrations were given in mg kg1 dry material. Organic
matter (OM) was expressed in percentage.
Nitrogen. Variety had a large effect (p=0.0003) on leaf
N concentrations (Table 1). A difference of 4.7 g kg-' in N
concentration was observed between the two soybean cultivars.
Leflore accumulated more N (43.62 g kg-) in its leaves than
Davis (38.97 g kg-1) (Table 2). Moreover, Davis showed a
tendency for N deficiency symptoms, the sufficiency range
lying between 42.5 and 50 g kg-1 N in the leaves (Jones, 1974;
Small and Ohlrogge, 1973). The leaf-N concentration
relationships are not well defined for soybean yet, due to the
confounding effect of N symbiotic bacterial fixation. Small
and Ohlrogge (1973) reported low N levels in leaf samples of
very productive fields. However, the lower (1.5-fold to 3.5-
fold) seed yield of Davis vs. Leflore, in the comparison study
done by Dickson and McSorley (1991), suggested interference of
N transported to the leaves due to damage of the root or
nodulation system by nematodes.
The application of nematicides had a small but
significant effect (p=0.046) on the N uptake in the soybean
leaves. The application of 0.56 kg a.i. ha-' of aldicarb
increased the concentration of N by 4.7 g kg-' when compared to
the control (0 kg a.i. ha-') (Table 3). No other difference was
observed among the different levels of the nematicide applied.
No nematicide-variety interaction was detected. The
differential responses due to variety and level of nematicide
did not affect N level in the soil. Since aldicarb had little
effect on either Leflore or Davis (Dickson and McSorley,
1991), N concentration results suggest, first a normal
symbiotic activity of Leflore and damage of Davis root system
by nematodes, second that the rates of aldicarb applied were
not sufficient to control the population densities of
nematodes in Leflore or Davis plots, and third that the N-
level difference in leaves with aldicarb treatment was not
directly related to yield.
Phosphorus. A large varietal effect (p=0.0001) was also
obtained for leaf P concentrations (Table 1). Phosphorus
seemed to have been sufficient in the leaves for both
varieties (Table 4), the optimum range being 3.0-5.0 g kg-1
(Jones, 1974). Frazier (1966), cited by Small and Ohlrogge
(1973), found no correlations between tissue P and K
concentrations and yields and no yield limitations due to high
P and K tissue concentrations.
An interaction (p=0.041, Table 1) was obtained between
variety and rates of nematicide for leaf P. There were
differences of 1.14, 0.52, and 0.66 g P kg-' between the two
varieties at the 0, 0.84, and 1.12 kg a.i. ha-' levels,
respectively, in favor of Leflore (Table 4). No difference
between the two varieties at the 0.56 level was detected. A
difference of 0.71 g kg-' of leaf P was obtained between the
0.56 and the 0 kg a.i of aldicarb, within the Davis plots
only. As was the case for N, the soil P concentrations did not
reflect the differential leaf P uptake obtained for the two
varieties and for the variety-nematicide interaction.
Potassium. Leflore accumulated (p=0.0001) more K (11.35
g kg-1) in its leaves than Davis (8.33 g kg-) (Table 2). Some
interference with the uptake of K was evident, the K
sufficiency range (20.0-25.0 g kg-; Jones, 1974) was not
reached for either of the cultivars. Concentrations of K in
the soybean leaves, however, were not affected by applications
of aldicarb (Table 1), which supported the results of no
effect of the four rates of aldicarb on yield of Leflore and
Davis reported by Dickson and McSorley (1991).
The experimental plots with Davis contained more soil K
than the ones with Leflore (p=0.0084). A difference of 26 mg
kg-' was obtained (Table 5), suggesting a lower extraction of
K by Davis, and matching the differential leaf K
concentrations.
Calcium. Leflore accumulated less Ca (p=0.0001) in the
leaves (11.76 g kg'-) than Davis (12.79 g kg-1) (Table 2). These
concentrations in the soybean leaves were sufficient for
optimum production (Jones, 1974). This difference was
reflected in a small difference in soil Ca concentrations
(Table 5). The experimental units with Leflore were higher in
soil Ca concentrations (0.232 g kg-1) than the ones with Davis
which extracted more soil Ca (0.02 g kg' ) than Leflore.
Nematicide applications resulted in no significant changes in
leaf Ca concentrations. The higher accumulation of leaf Ca by
Davis might have also resulted from a dilution effect through
a higher accumulation of dry matter by Leflore. Dilution
effect due to differential plant growth and increase in leaf
Ca concentrations with the physiological age have been
reported by Jones (1969).
Magnesium. Both variety (p=0.0001) and rates of aldicarb
(p=0.011) affected the concentrations of Mg in the leaves
(Table 1). The uptake was higher in Davis (3.20 g kg'1) than in
Leflore (2.24 g kg'1) leaves (Table 2). The Mg concentration in
Leflore leaves was not sufficient, the optimum ranging from
3.0 to 8.0 g kg-' (Jones, 1974). Increasing the levels of
nematicide interfered with the uptake of Mg. The leaf Mg
uptake in the 0-level plots with a mean of 3.03 g kg1' was
higher than in any other level of aldicarb. A highly
significant linear decrease (p<0.01) was observed as rate of
aldicarb increased.
No differences were observed for Mg concentrations in the
soil. The differential uptake in Mg due to variety and
nematicide was not sufficient to create differences in the
soil. A dilution effect due to higher growth and yield of
Leflore as reported by Dickson and McSorley (1991) might be
the cause of this varietal difference in leaf Mg
concentrations.
Copper. Variety alone had a significant effect (p=0.041)
on Cu uptake in the leaves (Table 6). Davis tended to
accumulate more Cu in the leaves than Leflore (Table 7). The
Cu concentrations are far below the sufficiency range of 6 to
30 mg kg-' as reported by Jones (1974) and by Small and
Ohlrogge (1973). Frazier (1966) cited by Small and Ohlrogge
(1973) observed that the higher the leaf Cu concentrations,
the higher was the yield, in a study involving 46 high-
yielding soybean fields. All the levels of nematicide gave
similar response. No differences were observed in the soil
test for Cu.
Manganese. A varietal difference (p=0.0001) was obtained
for the Mn concentration in the leaves (Table 6). Leflore
accumulated more Mn (142.56 mg kg"') than Davis (92.13 mg kg-')
(Table 7). The sufficiency range given by Jones (1974) lies
between 30 to 200 mg kg-'. Small and Ohlrogge (1973) reported
that Mn deficiency of soybean is seldom evident in the
southern part of the United States. The concentration of Mn in
the soil remained unaffected by this difference. Nematicide
levels did not show any effect on Mn uptake by the two soybean
varieties.
Iron. None of the treatment variables (variety and
nematicide, or their interaction) had an effect on the uptake
of Fe in the soybean leaves, nor on its concentrations in the
soil (Table 6). Both varieties had their leaf Fe
concentrations within the sufficiency range reported by Jones
(1974).
Zinc. A varietal difference in Zn concentration in the
soybean leaves was observed (p=0.0001) (Table 6). Leflore
accumulated 20.06 mg kg-' more leaf Zn than Davis (Table 7).
Concentrations in both cultivars were within the sufficiency
level, the optimum range being 20 to 50 mg kg-' in the leaves
(Jones, 1974). The application of nematicide had no effect on
the uptake of Zn. Soil test Zn levels were not affected by
treatments. Small and Ohlrogge (1973) reporting the study of
Frazier (1966) mentioned that higher ,soybean yield was
obtained with higher leaf Zn concentrations.
Soil PH and soil OM. A difference in pH (p=0.0003)
between the experimental plots exploited by the two varieties
was observed. Soil pH was lower for the plots occupied by
Davis (5.92) than for the plots with Leflore (6.09) (Table 5).
This difference might have resulted from the differential
uptake of cations due to variety effect in the soybean leaves
between the two cultivars (Table 2). The different levels of
nematicide had no effect on the soil pH. Percentage of soil
organic matter did not differ for any variable considered.
CONCLUSION
Varietal differences affected most of the leaf nutrient
element concentrations. Leflore accumulated more leaf N, P, K,
Mn, and Zn than Davis which accumulated more Ca, Mg, and Cu in
its leaves. Dilution effect due to better plant growth and
yield of Leflore might have explained the higher Ca, Mg, and
Cu concentrations in leaves of Davis (Jones, 1969). Dickson
and McSorley (1991) reported 1.5-fold to 3.5-fold greater
yield for Leflore than Davis. Leflore tended to have a better
nutrient balance in its leaves than Davis. No direct nematode
or nematicide effect on Leflore yield have been observed by
Dickson and McSorley (1991), who reported a suppression of
Davis yield (negative correlation) due to M. incognita
regardless of nematicide application.
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Table 1. Analysis of variance (Mean squares) of leaf N, P, K,
Ca, Mg for the varietal effect.
df N P K Ca Mq
Rep 3 21.06ns 0.12ns 27.51** 9.07** 0.37**
Variety 1 173.54** 3.24** 72.75** 8.53* 7.35**
Nematicide 3 29.38* 0.26ns 4.87ns 1.71ns 0.34*
Var x Nem 3 12.81ns 0.09* 0.46ns 0.15ns 0.04ns
Error 21 195.21 0.30 2.44 1.15 0.07
*, ** Significant at the 5% and 1% level, respectively.
ns = nonsignificant
Table 2. Leaf N, K, Ca, and Mg concentrations as affected
by the two soybean varieties.
Variety N K Ca Mg
------------------g kg---------------------
Leflore 43.623A 11.347A 11.761B 2.24B
Davis 38.966B 8.331B 12.794A 3.20A
Leaf concentration mean values not followed by the same letter
are significantly different at the 5% level, according to the
Duncan's Multiple-Range Test.
Table 3. Leaf N, K, Ca concentrations due to the effect of
Aldicarb rates.
Dosages
(kg a.i. ha-') N K Ca Mg
-----------------g kg------------------
0 39.11 9.15 12.95 3.03
0.56 43.77 10.91 12.21 2.60
0.84 41.31 9.89 11.93 2.66
1.12 40.99 9.41 12.02 2.61
0.56-0 4.66* -0.43**
0.84-0 2.20ns -0.37**
1.12-0 1.88ns -0.42**
0.84-0.56 -2.46ns 0.06ns
1.12-0.56 -2.78ns 0.01ns
1.12-0.84 -0.32ns -0.05ns
*, ** Significance at the 5%
ns = nonsignificant
and 1% level, respectively.
Table 4. Leaf P concentrations due to effect of variety and
of rates of nematicide.
Nematicide rates (kg a.i. ha-')
Variety 0 0.56 0.84 1.12
-----------------------g kg------------------
Leflore 3.87AX 3.66AX 3.64AX 3.71AX
Davis 2.73BY 3.44AX 3.12BXY 3.05BXY
Leaf concentration mean values not followed by the same letter
(A, B) within a column or (X, Y) within a row (variety) are
significantly different at the 5% level, according to the
Duncan's Multiple-Range Test and to polynomial contrasts,
respectively.
Table 5. Concentrations of soil K, Ca, and change in soil pH
ra +t* nvri +sa1 ffcmr*+
Variety K Ca pH
---------g kg- -------
Leflore 0.026B 0.23A 6.09A
Davis 0.034A 0.21B 5.92B
Leaf concentration mean values not followed by the same letter
are significantly different at the 5%, level according to the
Duncan's Multiple-Range Test.
Table 6. Analysis of variance (mean squares) of leaf Cu, Mn,
Zn. and Fe for the varietal effect.
df Cu Mn Zn Fe
Rep 3 1.86ns 3312.70** 111.45ns 11.46ns
Variety 1 7.03* 20351.53** 3220.03** 28.13ns
Nematicide 3 0.28ns 859.53ns 34.36ns 44.79ns
Var x Nem 3 0.531ns 509.95ns 133.45ns 128.13ns
Error 21 1.484 500.91 72.38 80.51
*, ** Significant at the 5% and 1% level, respectively.
ns = nonsignificant
Table 7.- Leaf Cu, Mn, Fe, and Zn concentrations due to the
varietal effect.
Cu Mn Fe Zn
------------mg/kg-------------------------
Leflore 2.69B 142.56A 80.00A 62.44A
Davis 3.63A 92.13B 81.88A 42.38B
Leaf concentration mean values not followed by the same letter
are significantly different at the 5%, level according to the
Duncan's Multiple-Range Test.
APPENDIX 1. Soybean leaf element concentrations, expressed as g kg-1 or
mg kg1 dry material, as affected by variety and rates of
nematicide.
D K Ca
Ma Cu Mn Fe Zn
,woJ v ..aa. -. -- ----
----------g kg------------ ----mg kg-1---
44.23 4.06 8.77 12.40 2.52
40.69 3.60 7.29 13.70 3.15
39.71 3.86 11.60 14.20 3.01
44.56 3.95 15.10 9.58 1.93
43.28 3.61 10.80 11.10 1.82
41.34 3.65 8.37 13.60 2.65
46.54 3.45 13.20 10.20 1.92
46.37 3.91 16.10 11.20 1.80
42.47 3.62 10.30 11.80 1.93
42.53 3.55 12.20 11.60 2.24
44.22 3.57 9.65 12.60 2.51
44.61 3.81 13.40 9.56 2.00
42.09 3.69 11.60 11.70 1.91
44.15 3.64 8.97 13.50 2.45
45.29 3.63 11.80 11.50 2.03
45.89 3.89 12.40 9.94 2.04
30.51 2.45 6.57 15.40 3.46
36.11 2.75 8.00 12.30 3.45
41.24 2.95 7.28 13.70 3.25
35.81 2.75 8.56 12.30 3.46
36.30 2.60 7.97 13.50 3.11
45.12 3.71 7.56 13.20 3.09
40.00 3.13 9.21 13.20 3.35
51.23 4.31 14.10 11.70 3.04
39.06 3.07 8.59 14.10 3.09
36.74 2.96 5.71 12.90 3.25
41.27 3.37 8.68 12.40 3.16
39.57 3.08 10.60 10.50 3.10
38.77 3.14 8.95 12.20 2.64
35.53 3.26 5.26 14.30 3.78
40.19 2.92 7.87 11.90 2.94
36.00 2.86 8.39 11.10 3.08
VAR=Variety
Level 1 of VAR= Leflore
Level 2 of VAR= Davis
NEM=nematicide rates:Level 1= 0 kg a.i. ha-1
Level 2= 0.56 kg a.i. ha"'
Level 3= 0.84 kg a.i. ha-'
Level 4= 1.12 kg a.i. ha'
4 180
4 160
2 160
3 91
2 170
3 160
2 110
3 110
3 180
2 130
3 110
2 100
2 170
2 180
4 140
2 130
5 120
5 68
3 98
1 70
4 110
6 160
2 73
4 100
6 69
2 83
3 94
3 53
3 87
4 110
4 100
3 79
100 74
80 66
80 64
80 62
70 74
70 51
80 50
90 61
70 67
80 60
90 53
70 55
70 78
80 62
90 61
80 61
80 44
80 29
80 54
80 35
80 40
90 61
80 37
100 61
100 45
80 34
80 49
80 34
70 42
80 40
70 38
80 35
~aa aba ll~b U~U
APPENDIX
2. Soil nutrient concentrations, expressed in g kg1 or mg kg'1, pH
and organic matter (OM in %) as affected by variety and rates
of nematicide.
ORB REP VARl NEM
N P K Ca Mg Cu Mn Fe Zn
----------g kg ------------ ------mg kg ------
0.38
0.38
0.43
0.30
0.36
0.30
0.36
0.35
0.42
0.47
0.41
0.43
0.45
0.35
0.35
0.50
0.41
0.24
0.38
0.35
0.53
0.43
0.38
0.44
0.47
0.31
0.37
0.32
0.41
0.71
0.34
0.36
0.063
0.054
0.052
0.034
0.062
0.065
0.040
0.038
0.053
0.053
0.048
0.041
0.064
0.056
0.050
0.032
0.070
0.056
0.048
0.036
0.052
0.062
0.037
0.042
0.057
0.052
0.044
0.032
0.054
0.063
0.052
0.037
0.022
0.026
0.030
0.034
0.029
0.018
0.034
0.039
0.024
0.020
0.023
0.023
0.027
0.020
0.027
0.024
0.036
0.027
0.050
0.037
0.033
0.024
0.036
0.060
0.048
0.022
0.024
0.036
0.029
0.024
0.034
0.024
0.301
0.268
0.216
0.146
0.282
0.308
0.178
0.162
0.265
0.267
0.197
0.168
0.316
0.269
0.213
0.155
0.279
0.226
0.183
0.146
0.236
0.272
0.174
0.181
0.244
0.270
0.172
0.141
0.223
0.288
0.206
0.166
0.022
0.020
0.018
0.016
0.019
0.022
0.018
0.021
0.018
0.020
0.017
0.016
0.022
0.018
0.016
0.016
0.022
0.019
0.017
0.016
0.017
0.020
0.017
0.024
0.020
0.020
0.016
0.015
0.017
0.023
0.018
0.015
0.12
0.12
0.12
0.08
0.16
0.12
0.16
0.08
0.08
0.08
0.08
0.12
0.24
0.16
0.08
0.16
0.12
0.20
0.12
0.16
0.12
0.16
0.04
0.08
0.24
0.12
0.12
0.12
0.16
0.12
0.12
0.12
4.80
3.28
3.84
3.24
5.20
3.92
2.88
3.44
3.72
3.20
3.28
3.28
4.80
3.96
3.88
2.48
5.60
3.28
3.36
2.52
4.00
4.80
2.68
4.00
5.60
3.24
3.28
2.64
4.80
4.80
4.40
2.72
8.4
7.6
10.4
12.0
8.8
8.0
9.6
13.2
7.6
8.0
10.4
11.6
9.2
8.4
11.2
10.0
9.2
8.0
9.2
9.6
9.6
8.0
9.2
14.0
12.4
8.4
9.6
10.4
10.8
8.8
10.0
10.0
1.20
1.88
1.12
0.52
0.96
1.28
1.36
0.84
1.88
0.80
0.92
0.64
1.36
2.12
1.16
0.64
1.24
1.24
0.68
1.28
1.92
1.08
1.56
2.08
1.44
0.96
0.88
0.56
0.84
1.36
1.00
1.56
VAR=Variety
Level 1 of VAR= Leflore
NEM=nematicide rates:Level 1= 0 kg a.i. ha"L
Level 2= 0.56 kg a.i. ha"1
Level 3= 0.84 kg a.i. ha'
Level 4= 1.12 kg a.i. ha-1
Level 2 of VAR= Davis
pH OM
%
6.2
6.4
6.0
5.8
6.2
6.3
6.0
5.7
6.2
6.4
5.9
5.9
6.2
6.4
6.0
5.8
6.0
6.1
5.8
5.8
5.8
6.1
5.8
5.5
5.8
6.2
6.0
5.8
5.8
6.4
5.9
5.9
1.2
1.1
1.2
0.9
1.5
0.9
1.1
1.1
1.3
1.0
1.2
0.9
1.5
1.0
1.3
1.1
1.5
0.9
1.3
1.0
1.3
1.1
1.1
1.2
1.8
1.0
1.2
1.0
1.5
1.1
1.3
1.0
OBS REP VAR NEM
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