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Copyright 2005, Board of Trustees, University
of Florida
r ,3 i Agricultural Research Center October 1979
PJ Research Report RC-1979-9 *
COMMERCIAL CORN VARIETY TESTING RES S
FROM SOUTH-CENTRAL FLORIDA, 19790
SJAN -
P. Mislevy, R. S. Kalmbacher, P. H. Everett and .-S. Homer-
Corn can be extremely valuable in a livestock feeding program.
With its rapid growth and high yielding ability, corn harvested and
stored as silage, can supplement perennial grasses at times when their
production is low. This crop may follow winter vegetables or be used
in a pasture renovation program. High quality corn silage can provide
cattle with a substantial carbohydrate input, possibly reducing high
grain costs and also providing growing calves with quality feed.
Well managed corn harvested for silage at the proper stage of
maturity can produce 7 to 10 tons/acre of dry matter in a 3.5 to 4.0
month period. This would allow the land to be free for the growth of
other crops during the remaining eight months.
Corn silage harvested at the hard dent stage usually contains 30-40%
dry matter and is high in energy, carotene, vitamin D, but low in minerals
with a protein content of about 8%. To produce high yields of quality
corn forage, adapted hybrids, proper seeding date, high fertility, water
control, correct plant populations, and weed and insect control are
necessary.
The purpose of these studies was to evaluate commercial corn
hybrids for silage and/or grain production at Ona and Immokalee.
Experimental Procedure
The experiments were conducted at the Agricultural Research Centers,
(ARC) at Ona and Imnokalee. The experimental design at both locations
was a randomized complete block with 4 replications. Twenty five commercial
corn varieties were seeded at Ona and 18 varieties at Immokalee. The
experiment at Ona was seeded on Ona fine sand February 9, 1979. The
Immokalee experiment was seeded on January 31, 1979.
1/ Associate and Assistant Professors, Agricultural Research Center, Ona;
Professor, Agricultural Research Center, Immokalee; Professor,
Agronomy Department, Gainesville, Florida.
-2-
Fertility
Fertilization practices carried out at Ona were 0-120-240 lb/A
N-P205-K20 at seeding. Additionally, 50, 100 and 100 Ib/A N was applied
when the corn was 5, 12, and 24 to 28 inches tall, respectively.
At Immokalee 40-110-220 lb/A of N-P205-K20 was disked into the
seedbed. When plants were 12 and 20 to 24 inches tall an additional
100 lb/A of N as ammonium nitrate was applied (side-dressed) at each
height. The side-dressed nitrogen was applied in a band near the corn
row and covered with soil by a rolling coulter. The effect of this
treatment was to place the fertilizer in the soil, to be carried by
capillary water movement in this seepage-irrigated experiment.
Plant populations and pest control
Corn at Ona was seeded in 30 inch rows to a final population of
26,000 plants per acre. In Immokalee the corn was seeded in 30 inch
rows to a final population of 24,000 plants per ace. The herbicide
practices used at Ona were 2.0 Ib active/A AAtrex' and 1.0 lb active/A
ProwlR) pre-emerge in 40 gallons of water per acre. No cultivation
practices were employed after the corn was seeded. The insecticide
Counter(R)15G (2.0 Ib active/A) wa applied at seeding, to control soil
insects. The insecticide Mesurol was applied on the seed at the
rate of 1 lb commercial product/100 lb seed to act as a bird repellent.
At Imqkalee AAtrex(R) was applied at 2.0 Ib activeA in combination
with Dual) at 2.5 lb active/A. At seeding ,e insecticide Furidan(R)
10G was applied at 2.0 lb active/A. Mesurol( was a lied at the same
rate used at Ona. Corn was sprayed with Lannate 1.8L" on March 14, 20
and 26, 1979, at 2 pints/100 gal. of water to control bud worms.
Irrigation
The initial irrigation at Ona was applied with an overhead system
immediately following seeding. A total of 4.2 inches of irrigation
water was applied in 6 applications at the Ona ARC. The Immokalee
experiment was irrigated by a seepage system with laterals on 40 foot
centers.
Maturity at Harvest
Corn was harvested for silage when the kernels were at the hard
dent stage, with plants containing approximately 33 to 47 and 40 to 53%
dry matter at Ona and Immokalee, respectively. This was coincidental
with black-layer formation at base of kernel in most varieties.
-3-
The experiments were also harvested for grain. The kernel moisture at
harvest over all varieties at Ona and Immokalee averaged 33 and 29%,
respectively. These values were then converted and expressed in bushels
of shelled corn at 15.5% moisture. No lodging was observed among varieties
at Ona or Immokalee.
Results and Discussion
Ona ARC
Dry matter forage yields were quite good, averaging from a high
of 13.0 T/A for the full season hybrid 'Dekalb XL 395A' to a low of
8.3 T/A for the early maturing hybrid 'Funks G4507' (Table 1). Due to
large variation between replications, a 4.0 T/A dry matter difference
between hybrids was required before statistically significant differences
were found.
The top yielding hybrid (Dekalb XL395A) dried quite rapidly after
maturity as evidenced by the 42.4% dry matter at harvest. This varietal
characteristic is quite important, since fast dry-down indicates the
variety would be ready for whole plant harvesting sooner, allowing the
commercial grower to remove the crop before the start of summer rains.
The use of early maturing hybrids such as 'McCurdy 84AA', 'Asgrow RX 112'
and 'Funks G4507' also play an important role in a commercial corn program.
These varieties mature about 7 to 15 days earlier than full season hybrids,
allowing one to start harvesting sooner. Early maturing hybrids generally
produce low dry matter yields (Table 1) but grain yields and grain to
stover ratios are quite good.
When selecting a corn hybrid to be grown in south central Florida,
grain production should be an important consideration. Grain yields in
1979 ranged from a high of 212 bu/A @ 15.5% moisture for 'McCurdy 75-200'
to a low of 154 bu/A for the mid season variety 'Funks G4810'. Kernel
moisture at harvest of the mid-season variety McCurdy 75-200 was also
good averaging 32.1%. Since shelled corn should contain 13 to 14% moisture
for safe storage, the lower the moisture at harvest, the lower the energy
requirement for drying. The early maturing hybrid Funks G4507 contained
the driest kernels at harvest (6-25-79), averaging 25.9% moisture.
An important consideration when selecting corn hybrids for silage
is the grain-stover ratio. This is the amount of dried grain produced
by the corn plant in relation to total (corn stover plus grain) production.
The grain-stover ratio expresses to the commercial grower the percentage
by weight of grain available in the silage. Producing a corn crop with
a high forage dry matter yield and low grain yield ('Coker 77') results
in a low grain-stover ratio (36-64%) (Table 1). Whereas 'Coker 18' produced
a low forage dry matter yield and high grain yield resulting in a 62-38% ratio.
When selecting a commercial corn hybrid for silage, high forage and grain
yields with a grain-stover ratio of 50-50 or higher, should be considered.
Southern corn rust (Puccinia polysora) did not appear to be a
serious problem on any commercial corn hybrids grown at Ona in 1979.
Immokalee ARC
There were significant differences in dry matter production among
the 18 entries tested at Immokalee (Table 2). The highest yielding
entry was 'Dekalb 1295', which produced 9.0 tons of dry matter per acre.
The lowest yielding entry was Asgrow RX 112, which produced 5.5 T/A.
Average forage yield was 7.4 T/A. Generally, full season hybrids, like
Dekalb 1295, Coker 77, Dekalb XL395A were higher yielding, than mid and
short season hybrids, like 'Coker 22', Funks G4507, 'Dekalb XL80B'.
Forage dry matter of 18 varieties averaged 46.3% at harvest (Table 2),
which is somewhat higher than normal because this trial was seeded
earlier than normal and was harvested later. As would be expected the late
hybrids were lower in dry matter percentage while the early hybrids (well
past maturity) are quite high in dry matter.
There were significant differences in grain yield among entries
tested, and high grain yields were not always associated with the full
season hybrids (Table 2). Although Dekalb 1295 and Dekalb XL395A were
among the top grain yielders (176 and 179 bu/A, respectively), some
short and mid-season entries, such as 'McCurdy 67-14' and 'McNair S-338'
were high grain yielders as well, producing 171 and 176 bu/A, respectively.
Average grain yield for all varieties was 157 bu/A with a range of 179
to 136 bu/A.
Even at this late harvest date kernel moisture averaged 29.4% with
a range of 35.2% (Dbkalb 1295) to 22.27. (Funks G4507). Any entry
harvested on a commercial basis would require drying for safe storage.
Growing corn for shelled grain may not be practical in south Florida
when drying costs are considered.
The Immokalee trials were shelled in the field, as opposed to
drying the ears, and then shelling, as was done at Ona. Consequently,
the shelling percentages are lower for the hybrids grown in Immokalee
(Table 2). The average shelling percentage was 78.5% (as opposed to 86.2%
at Ona, Table 1).
The ratio of grain to stover was greater in the short season hybrids
than in the late hybrids (Table 2). Grain-stover ratios in the range
of 55-45 are not uncommon for short season hybrids. Theyproduce a short
stalk with a large ear, whereas the full season hybrids produce a large
.stalk with perhaps the same size ear.
Grain-stover ratios at Ona are smaller than those ratios at Immokalee.
This was because the individual plant yields are smaller at Immokalee
and ear size is apparently large. Average grain-stover ratios at
Immokalee were 52-48 vs. 48-52 at Ona.
Conclusions
When selecting a commercial corn hybrid to be grown and stored
as silage in south-central Florida, it is best to select a variety,
that produces high forage and grain yields, with a high forage dry
matter percentage and low kernel moisture percentage. A grain-stover
ratio of about 50-50 or above should also be considered. If corn
hybrids are grown for grain production, then high grain yields at
low kernel moisture should be considered.
-6-
Table 1. Forage and grain yields and other agronomic variables of
commercial corn varieties grown at the Ona, ARC 1979.
Forage dry matter
Brand Variety Yield At harvest
T/A %
Dekalb
McCurdy
Coker
Dekalb
McCurdy
McNair
Pioneer
PAG
Asgrow
Funks
Funks
Funks
Funks
Funks
Pioneer
McCurdy
Pioneer
Asgrow
Funks
Asgrow
Funks
Dekalb
Pioneer
Coker
Funks
XL395A
75-200
77
1295
67-14
508
X304 C
751
RX140 A
G28555
G5945
G4864
G4709
G4810
X306B
84AA
XA730 C
RX112
G4606
RX114
G4776
XL 80B
X 5407
18
G4507
13.0
12.8
12.2
12.0
11.8
11.3
11.3
11.0
10.6
10.6
10.5
10.5
10.4
10.3
10.2
10.1
9.9
9.8
9.8
9.6
9.2
9.2
9.2
9.2
8.3
42.4
38.8
33.3
39.5
41.5
39.7
37.2
38.9
39.3
39.5
37.3
37.3
40.5
36.6
36.3
43.6
39.8
44.6
39.2
42.1
39.8
39.6
41.9
39.1
46.8
Grain
yield
bu/A
197
212
165
211
207
177
192
158
196
199
199
178
174
154
180
175
181
167
170
186
186
169
193
196
159
a-d
a
b-d
a
ab
a-d
a-d
cd
a-d
a-c
a-c
a-d
a-d
d
a-d
a-d
a-d
b-d
a-d
a-d
a-d
a-d
a-d
a-d
cd
Kernel
moisture
%7
36.2
32.1
34.3
35.4
35.2
35.4
37.8
36.1
30.5
34.0
32.6
32.3
28.2
32.8
37.6
31.1
32.5
27.9
27.1
29.9
30.6
32.1
29.7
33.8
25.9
ab
b-f
a-d
a-c
a-c
a-c
a
ab
d-g
a-d
b-e
b-f
e-h
b-d
a
c-g
b-e
f-h
gh
d-h
d-g
b-f
d-h
a-d
h
Shelling gGrain-stover
percentage ratio@
% 7
85.4
85.5
84.8
83.8
84.9
84.0
85.1
85.7
81.8
87.7
85.4
87.0
87.6
84.6
84.6
90.0
86.9
85.9
86.7
85.9
85.7
85.0
87.2
90.1
88.5
c-f
b-f
c-f
fg
c-f
e-g
c-f
b-f
g
a-c
c-f
b-e
a-d
d-f
d-f
a
b-e
b-f
b-f
b-f
b-f
c-f
b-d
a
ab
42-58
45-55
36-64
46-54
47-53
41-59
46-54
39-61
48-52
52-48
53-47
48-52
47-53
40-60
47-53
48-52
51-49
47-53
48-52
52-48
56-44
50-50
57-43
62-38
53-47
Average 10.5 39.8 183 32.5 86.2 48-52
Means within a column followed by the same letter are
not significantly
different at the 0.05 level of probability according to Duncan's
Multiple Range Test.
tBased on 15.5% moisture.
bDetermined at harvest.
Calculated on dry matter basis.
Seeding date: 2-9-79
Plant population (final) 26,000 plants/acre.
Insecticide: Counter 15G @ 2 Ib active/A, preplant applied.
Row spacing: 30 inches,
Fertilization: Preplant, 1200 Ib/A 0-10-20, N-P205-K20; When corn was
5 inches tall, applied 50 Ib/A N; corn 12 inches and 24 inches, applied
100 lb/A N at each height.
Herbicide: Pre-emerge 2 lb active/A AAtrex and 1 lb active/A Prowl.
Harvest date: June 26, 1979.
Irrigation: applied 4.2 inches via over-head sprinklers.
Table 2. Forage and grain yields and agronomic variables of commercial
corn varieties grown at the Immokalee ARC, 1979.
Forage dry matter
Brand Variety Yield At harvest
T/A %
Dekalb
Coker
McCurdy
Dekalb
McCurdy
Pioneer
Funks
Funks
McNair
McNair
Asgrow
Pioneer
Pioneer
PAG
Coker
Funks
Dekalb
A w
1295
77
67-14
XL395A
75-200
X306B
G5945
G4864
508
S-338
RX 140A
X304A
X5407
751
22
G4507
XL80 B
YV1 19
9.0
8.7
8.4
8.3
8.3
8.0
7.9
7.8
7.6
7.5
7.0
6.9
6.8
6.5
6.5
5.8
5.8
5 5
a*
ab
a-c
a-c
a-c
a-c
a-c
a-d
a-e
a-e
a-e
a-e
b-e
c-e
c-e
de
de
P
39.5
41.9
51.0
44.4
51.3
45.5
45.9
49.6
41.7
50.8
47.6
40.9
47.2
46.8
44.7
46.5
45.2
52.8
e
b-e
a-c
a-e
ab
a-e
a-e
a-d
c-e
a-c
a-e
de
a-e
a-e
a-e
a-e
a-e
a
Graint Kernelt
yield moisture
bu/A %
176
156
171
179
149
163
151
169
152
176
154
136
148
136
155
157
145
145
ab
a-c
ab
a
bc
a-c
a-c
ab
a-c
ab
a-c
c
bc
c
a-e
a-c
bc
bc
35.2
33.6
28.6
33.7
30.0
30.4
29.7
25.5
33.4
26.4
27.1
31.6
31.7
29.8
25.4
22.2
29.8
25.6
a
ab
d-g
ab
b-f
b-e
c-f
gh
a-c
fg
e-g
a-d
a-d
b-f
gh
h
c-f
eh
Shelling jGrain-stover
percentage ratio
% 7
78.9
78.9
76.9
81.3
79.5
73.8
78.4
79.2
79.7
76.7
78.8
74.0
80.3
80.9
81.9
80.8
72.9
79.6
49-51
45-55
50-50
56-44
46-54
47-53
48-52
54-46
51-49
55-45
55-45
46-54
55-45
54-46
57-43
60-40
59-41
58-42
Average 7.4 46.3 157 29.4 78.5 52-48
Means within a column followed by the same letter are not significantly
different at the 0.05 level of probability according to Duncan's Multiple
Range Test.
tBased on 15.5% moisture.
tDetermined at harvest.
Calculated on dry matter basis.
Plant population: 24,000 plants/acre.
Seeding date: January 31, 1979.
Fertilization: At seeding 40-110-220 of N-P205-K20/acre; 100 Ib N/A when
plants 12" tall, 100 lbs N/A when plants 20-24" tall.
Insecticide: Furidan 10G at 2 Ibs active/A.
Lannate 1.8L was sprayed March 14, 20 and 26 at 2 pts/100 gallon H20 to
control bud worms.
Row spacing: 30 inches.
Herbicide: Dual at 2.5 Ib active/A plus AAtrex at 2.0 Ib active/A.
Irrigation: seepage, with laterals on 40'centers.
Harvest date: June 18, 1979.
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