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Group Title: Agronomy research report - University of Florida Institute of Food and Agricultural Sciences ; AY-96-01
Title: Response of corn cultivars to experimental chemical spray treatment
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Permanent Link: http://ufdc.ufl.edu/UF00056105/00001
 Material Information
Title: Response of corn cultivars to experimental chemical spray treatment
Series Title: Agronomy research report
Physical Description: 10 leaves : ; 28 cm.
Language: English
Creator: Gallaher, Raymond N
McSorley, R ( Robert )
Biggs, R. Hilton ( Robert Hilton ), 1931-
University of Florida -- Agronomy Dept
Publisher: Department of Agronomy, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1995?]
 Subjects
Subject: Corn -- Field experiments -- Florida   ( lcsh )
Corn -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
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Bibliography: Includes bibliographical references (leaves 4-5).
Statement of Responsibility: Raymond N. Gallaher, R. McSorley, and R. H. Biggs.
General Note: Cover title.
General Note: Chiefly tables.
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Bibliographic ID: UF00056105
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 62591968

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida





/a oFL-


Agronomy Research Report AY-96-01




Response of Corn Cultivars to Experimental
Chemical Spray Treatment




Raymond N. Gallaher', R. McSorley2 and R. H. Biggs3

Professors of Agronomy' and Entomology and Nematology2, Inst. Food
and Agr. Sci., Univ. of Florida, and Ph.D. Horticulture3,
Gainesville, 1995.


Marston Sci.nc :

JAN 16 1991

University of Florida







Agronomy Research Report AY-96-01


Response of Corn Cultivars to Experimental Chemical Spray Treatment


Raymond N. Gallaher', R. McSorley2 and R. H. Biggs3

Professors of Agronomy' and Entomology and Nematology2, Inst. Food and Agr.
Sci., Univ. of Florida, and Ph.D. Horticulture3, Gainesville, 1995.

INTRODUCTION

Corn (Zea mays L.) is an important crop all over the USA and world for both
human consumption and animal feed. Genotypes differ in their response to
environments. Therefore, it is important to test cultivars of corn for yield in
the environment that they will be growing. University of Florida is in the
process of developing subtropical hybrids and varieties to fit into our
subtropical and multiple cropping environment. Many variables other than
genetics also influenced crop development and growth. The first objective of
this study was to determine if University of Florida experimental genotypes of
corn would yield equal or superior to recommended commercial corn hybrids. The
second objective was to test the corn cultivars for response to application of
a commercial chemical spray treatment.

MATERIALS AND METHODS

The experiment was conducted on land 14 miles west of Gainesville, Florida
and 2 miles north-west of the University of Florida, Inst. Food and Agr. Sci.,
Agronomy Farm. The land is used to grow corn silage by Mr. Dale and Mr. Donald
Haufler of Gainesville, Florida. The soil is typical of the Arredondo sand.
After moldboard, and harrow tillage the site was planted using a two-row in-row
subsoil no-tillage planter on 22 and 23 March 1995. Anhydrous ammonia (71 kg N
ha`) was injected under the row during the planting operation. Complete
fertilizer was broadcast over the top of the planted corn on 30 March at the kg
ha-l rate of 16 N, 39 P20,, 94 K,2, 9.4 Mg, 19.6 S, 1.56 B, 12.5 Zn, 22 Mn and 1.23
Cu. This was tilled into the soil on 14 April with a rototiller cultivator which
also aided in control of a heavy infestation of Johnsongrass (Sorqhum halepense
L. Pers.). On 22 April 89 kg K0O ha'l was broadcast over the top of the young
growing corn. An additional 178 kg N ha"' was sidedressed on 28 April followed
by a second cultivation on 1 May.

The experiment was a split plot with eight cultivars of corn as whole plots
and subplots were with and without application of a commercial chemical liquid.
The corn included a University experimental subtropical hybrid, a experimental
subtropical population, a commercial tropical hybrid and five commercial
temperate hybrids. The liquid chemical treatment material was provided by
E.K.M.A., Inc, P.O. Box 560186, Miami, FL. Beginning one month after corn
planting the first of three split applications (5.55 L ha"' each time) of the
chemical treatment was sprayed on the young corn. Therefore, the chemical was
applied on 26 April, 1 May and 4 May. The application on 4 May was the last
possible date one could spray due to the rapidly growing and tall corn plants.

Corn ear leaf diagnostic tissue was collected from 25 to 28 May at the
early stages of silking and tasseling. A total of 10 leaves were collected at
random from each hybrid and spray treatment per replication. These leaves were
washed to avoid any possible micronutrient contamination adhered to the external
surfaces of the leaves (Futch and Gallaher, 1994; Gallaher, 1995). Leaves were
dried at 70 C in a forced air oven, ground in a Wiley mill to pass a 2 mm
stainless steel screen and stored in air tight plastic storage bags. Before
analysis, sample bags were opened and ground samples were redried at 70 C for a
minimum of 2-hr in a convection oven to remove differentially adsorbed/absorbed








moisture. Kjeldahl N was determined (Gallaher, Unpublished) (Gallaher, et al.,
1975). Phosphorus, K, Ca, Mg, Fe, Cu, Mn, Zn and Na were determined by ICAP
(Inductive Coupled Argon Plasma).

At the same time that ear leaf samples were collected for diagnostic tissue
analysis, from 25 to 28 May, whole plant samples were collected from one square
meter for growth differences and other measurements. Ear leaves and other leaves
were removed followed by leaf area measurements on a electronic area meter
(Licor-LI-3100). Ear leaves, other leaves and stalk was weighed for fresh
weights, dried in a forced air oven at 70 C and weighed again for dry matter.
Yield weights are reported on a square meter basis.

Soil samples were collected randomly from each replication prior to
beginning the spray treatments on 25 April and final samples were collected on
3 July after corn had been harvested. Following a period of air drying the soils
were sieved to pass a 2mm stainless steel screen. Soil was analyzed for Mehlich
I (Mehlich, 1953) extractable nutrients (P, K, Ca, Mg, Cu, Fe, Mn, and Zn (also
Na) by use of ICAP. Soil N was analyzed by microKjeldahl procedures (Gallaher,
Unpublished) (Gallaher, et al., 1975). Organic matter was analyzed by use of a
modified Walkley-Black procedures (Black, 1965; Jackson, 1958). One soil to two
water ratio was used for pH by combination electrode. Cation exchange capacity
was by cation summation procedure (Hesse, 1972; Jackson, 1958).

Soil samples for nematode analysis were collected on 26 April and 28 June
1995. Each soil sample consisted of six cores (2.5 cm in diameter x 20 cm deep)
collected from an individual plot. From each soil sample, a 100-cm3 subsample
was removed for nematode extraction, using the sieving and centrifugation
procedure (Jenkins, W.R., 1964).

Approximately three square meters of area of whole corn plants was sampled
26 June to determine whole plant yield near the time the Haufler brothers
harvested the field for silage (3 July). These samples were weighed in the field
and subsampled for dry matter estimate. Subsamples were dried at 70 C in a
forced air oven. Yield data was adjusted to kg m2.

All data was recorded into Quattro Pro (1987) spreadsheet for
transformations and for ASCII files. Analysis of variance and mean separation
was by use of MSTAT 4.0 (1985) using a microcomputer. Means were separated if
difference were found at the 0.05 level of probability.

RESULTS AND DISCUSSION

Corn Yield and Leaf Area

Corn cultivars differed in all variables measured at the first sampling
date silkingg and tasseling) (Table 1). Of particular interest was the
University of Florida experimental, both of which ranked at the top or near the
top in total leaf area. In fact FLASTOP had the largest leaf area index of all
cultivars (5.79) and also had the largest plant dry matter yield at this time
(Table 1). It is encouraging to note that FLASTOP, an open pollinated population,
had a high performance ranking with the commercial hybrids. This provided
further evidence that the material would be competitive if released as a new open
pollinated variety. Final yield at silage harvest time shows that not only does
FLASTOP rank near the top but Howard III, a experimental hybrid, also ranks at
or near the top for silage production compared to the commercial hybrids in this
test.

Limited evidence, of a positive nature, was found in favor of the spray
treatment regarding yield (Table 1). However, total leaf area appeared to be
increased by a 2.5% when averaged across all hybrids. If this is a real effect
then the question could be ask whether the chemical would have provided a greater
response if it had been applied earlier in the life cycle or if more chemical had







been applied or if the corn was grown under other soil and management conditions?
In either case here both sprayed and unsprayed treatments had a leaf area index
greater than 4 which would indicate that greater leaf area in this situation may
not be necessary to maximize yield. Final whole plant yield at silage harvest
time shows strong evidence that tropical or subtropical corn may respond to the
chemical treatment but not the temperate corn (Table 1). Better controlled
experimentation and repeated experiments would be necessary before drawing firm
conclusions from the benefit of or lack of benefit from use of the spay material
to increase corn yield.

Diagnostic Corn Ear Leaf Analysis

Corn is considered to be sufficient in nutrients with the following
concentrations: 27.0-40.0 g N kg-'; 2.50-5.0 g P kg-'; 17.0-30.0 g K kg-'; 2.10-10.0
g Ca kg-'; 2.00-10.0 g Mg kg-'; 6-20 mg Cu kg-'; 21-250 mg Fe kg-'; 20-200 mg Mn kg-';
and 25-100 mg Zn kg"' (Jones et al., 1991). Using these sufficiency levels as
indicators it was observed that all but one cultivar would have been low in Mg
(Table 2). However, photosynthesis is only reduced from low Mg concentrations
when the appearance of chlorosis is observed at a Mg value below 1.30 g Mg kg'
(Moss and Peaslee, 1965; Peaslee and Moss, 1966). The large application of K
fertilizer in this study likely was responsible for the reduction in Mg
concentration. Under low soil test K the application of K fertilizer generally
increases the rate of photosynthesis in corn up to the point just before K will
induce a Mg deficiency (Gallaher, et al., 1972; Gallaher, et al., 1975; Gallaher
and Jellum, 1976a; Gallaher and Jellum, 1976b;. Most of these corn cultivars
were on the border line of what was likely a K induced Mg deficiency. It is also
noted that the hybrids responded differently between spray and unsprayed
treatments but did not respond positively or negatively to the spray treatment
(Table 2). All other plant nutrients fell within the sufficiency range for
healthy corn (Jones et al., 1991).

Soil Test Measurements

Many of the soil nutrients were in greater quantities in the nonspray
treatment at both sampling dates (Table 3). This indicates that the relationship
that occurred when the experiment began was retained up to harvest time.
Although statistical analysis between soil sampling dates was not logical to
perform in this study, a trend appears for N, Ca, Mg, CEC and organic matter to
increase from the first to the last soil sample date. If this is a real increase
an explanation might be as follows: Increased soil N and Mg could occur from the
application of unused fertilizer N and Mg. Soil organic matter increase would
logically be due to corn roots at maturity that were not present at the first
soil sampling date. The increased CEC would logically occur due to increased
organic matter and extractable cations. No speculation is given for the
increased Ca.

Soil test values appear to be adequate for growing a good corn crop with
the exception of K and Mg. Because of the relatively high corn silage yield it
is expected that most of the fertilizer K would be removed in the crop.
Therefore, close attention to application of adequate K would be important to
ensure good growth. Also, application of Mg should be a part of the
recommendation to offset the potential for K induced Mg deficiency. Soil pH is
adequate for growing a good corn silage crop.

There were no obvious differences in soil test values that can be
attributed to the application of the chemical spray treatment. Without knowing
the exact composition of the chemical spray it is not possible to adequately
determine spray-soil test relationships.

Nematodes

The corn cultivars hosted populations of ring, stubby-root, lesion, and








root-knot nematodes (Table 4). There were no differences in numbers of any of
these nematodes between untreated plots and plots treated with the chemical
spray. Some differences among corn cultivars were observed in numbers of root-
knot nematodes measured on 28 June, but not for other nematodes. No significant
interactions between spray treatment and cultivar were observed for any of the
nematodes found. It is concluded that the chemical spray treatment had no effect
on nematode numbers, and that the choice of corn cultivar had little effect on
nematode numbers. It was noted that the two Florida experimental subtropical
cultivars had over 50% fewer root-knot nematodes compared to the commercial
tropical hybrid Pioneer X304C. However, the slight reduction in numbers of root-
knot nematodes observed on some corn cultivars do not seem great enough to be of
much practical importance. Further verification of the noted differences and the
economic impact needs further verification and study.

SUMMARY AND CONCLUSIONS

Florida experimental subtropical hybrid and open pollinated population were
very competitive with commercial tropical and temperate hybrids for leaf area
development and final plant yield. Tropical and subtropical corn types showed
a tendency to have greater dry matter yield for silage compared to commercial
temperate hybrids. Chemically sprayed treatment leaf area index averaged over
the eight cultivars of corn was 2.5% greater than the nonspray chemical
treatment. However, due to the large leaf area index in this study it is not
expected that the increase in leaf area would result in increased yield. It is
concluded that the chemical spray treatment had no effect on nematode numbers,
and the choice of corn cultivar had little effect on nematode numbers. Further
testing and economic evaluation would be necessary to confirm the benefits of the
reduced numbers of root-knot nematodes on Florida experimental subtropical
cultivars over the commercial tropical hybrid Pioneer X304C. Further testing
under different timing of application, rates of chemical spray and management
conditions would be necessary to determine the benefits of this chemical for
improvement in corn leaf area, yield, quality, and nematode relationships.

ACKNOWLEDGEMENT

The authors appreciate the technical assistance of Mr. Jim Chichester, Mr.
Howard Palmer and Mr. Walter Davis. The cooperation and assistance of Mr. Dale
and Mr. Donald Haufler is also appreciated as well as the contributions of
materials from E.K.M.A., Inc.

LITERATURE CITED

Black, C.A. 1965. Methods of Soil Analysis, Part I and II. Amer. Soc. of
Agronomy, Inc., Madison, Wis.
Futch, S.H., and R.N. Gallaher. 1994. Citrus leaf wash comparison of zinc
nutritional and nutrient uptake analysis. Agronomy Research Report AY-94-
06. Agronomy Department, Inst. Food and Agr. Sci., Univ. of Florida,
Gainesville.
Gallaher, R.N., W.L. Parks, and L.M. Josephson. 1972. Effect of levels of soil
potassium, fertilizer potassium, and season on yield and ear leaf potassium
content of corn inbreds and hybrids. Agron. J. 64:645-647.
Gallaher, R.N., W.L. Parks, and L.M. Josephson. 1975. Some factors influencing
yield and cation sum and ratios in corn. Commun. Soil Sci. & plant Anal.
6(1):51-61.
Gallaher, R.N., C.O. Weldon, and F.C. Futral. 1975. An aluminum block digester
for plant and soil analysis. Soil Sci. Soc. Am. Proc. 39:803-806.
Gallaher, R.N., and M.D. Jellum. 1976a. Elemental and/or cation ratio
efficiency of corn hybrids grown on an infertile soil inadequate in
magnesium. Commun. Soil Sci. & Plant Anal. 7(7):653-664.
Gallaher, R.N., and M.D. Jellum. 1976b. Influence of soils and planting dates
on mineral element efficiency of corn hybrids. Commun. Soil Sci. & Plant
Anal. 7(7):665-676.







Gallaher, R.N. 1995. Comparison of Zn nutritional spray treatments for citrus
leaf Zn adsorption and absorption. Agronomy Research Report AY-95-02.
Agronomy Dept., Inst. Food and Agr. Sci., Univ. of Florida, Gainesville.
Hesse, P.R. 1972. A textbook of Soil Chemical Analysis, Chemical Publishing Co.,
N.Y. pp. 91-105.
Jackson, M.L. 1958. Soil Chemical Analysis. Prentice-Hall, Inc., Englewood
Cliffs, NJ. pp. 59-67.
Jenkins, W.R. 1964. A rapid centrifugal-flotation technique for separating
nematodes from soil. Plant Dis. Reptr. 48:692.
Jones, J.B., Jr., B. Wolf, and H.A. Mills. 1991. Plant Analysis Handbook.
Micro-macro Publishing, Inc. Athens, GA.
Mehlich, A. 1953. Determination of P, Ca, Mg, K, Na and NH4. North Carolina
Soil Test Division (Mimeo, 1953). North Carolina State Univ. Raleigh, NC.
Moss, Dale N., and Doyle E. Peaslee. 1965. Photosynthesis of maize leaves as
affected by age and nutritional status. Crop Science. 5:280-281.
MSTAT 4.0. 1985. Software for statistical analysis. User's manual. Michigan
State University. East Lansing, MI.
Peaslee, Doyle E., and Dale N. Moss. 1966. Photosynthesis in K and Mg deficient
maize leaves. Soil Sci. Soc. Amer. Proc. 30:220-223.
Quattro Pro 4.0. 1987. Spreadsheet for data processing. Borland International.
Walsh, L.M. 1971. Instrumental Methods of Analysis of Soil and Plant Tissue.
Soil Sci. Soc. Amer., Madison, Wis.






Table 1. Yield and leaf area of eight corn cultivars treated with a commercial chemical.
Corn Ear Leaf' Total Plant Leaves'
Cultivar Fresh Wt. Dry Wt. Area Fresh Wt. Dry Wt. Area


g---- "2


Cm2 m-2


-------g m-2 -----


m2 m-2


Howard III
Pioneer Brand X304C
FLASTOP
Pioneer Brand 3154
DeKalb 706
ICI 8105
ICI 8100
Asgrow RX949W

Spray Average
No Spray Average

CV =


120
126
148 bi
139
153 b
186 a
158 b
129

145 NS
144

8.42%


e 31.6 bc
de 26.4 d
S 35.3 ab
:d 32.2 abc
36.3 a
34.3 ab
29.8 cd
de 26.5 d


31.5 NS
31.6

12.83%


4338
4148
5387 a
4321
4997 1
5104 al
4675
3805


4618 NS
4576

6.43%


de 1268 cd
ef 1323 d
1654 a
de 1181 d
,c 1380 bc
1582 a
cd 1446 b
f 1281 cd


1397 NS
1381

7.58%


305 c 41047 1
262 d 39812
382 a 57929 a
272 d 36104
334 b 43524 1
296 c 42645 1
266 d 42358 1
264 d 36988


300 NS
295

8.05%


43080 *
42022

4.96%


Stalk'
Dry Wt.


Total Plant"
Fresh Wt. Dry Wt.


Total Plant Yield at Harvest Time"
Sprayed Unsprayed


------------------- M2 --------------------2
------------- ----- (n ----------_____


---- Kg Plant Dry Matter m-2


Howard III
Pioneer Brand X304C
FLASTOP
Pioneer Brand 3154
DeKalb 706
ICI 8105
ICI 8100
Asgrow RX949W

Spray Average
No Spray Average


CV =


3573 e 560
4487 cd 673
5455 ab 1005
3940 de 702
5329 b 928
6034 a 857
4977 bc 657
4656 c


4842 NS
4771

10.89%


a

ab
I:


779 NS
778

18.17%


c 4721
c 5684
6964 ab
c 4982
6556 be
7430 a
c 6265 b
845 b 5


6094 NS
6008

10.06%


f 865
de 935
1387
ef 975
S 1262
1153
:d 923
308 cd


Howard III, Florida experimental subtropical hybrid; Pioneer Brand X304C, tropical hybrid; FLASTOP, Florida
experimental subtropical population; Other corn are temperate hybrids. Values in columns among corn cultivars
not followed by the same letter are significantly different at the 0.05 level of probability according to
Duncan's multiple range test. NS = non significant and = significant differences at the 0.05 level of
probability when comparing between sprayed and unsprayed. CV = coefficient of variation. Divide total leaf
area by 10,000 to get leaf area index. # = Silking and Tasseling date. ## = Silage harvest date.


Fresh Wt.


d
d
a
cd
ab
b
d
1109


2.23
1.99
1.84
1.59
1.51
1.54
1.44


a
b
b
c
cd
cd
cd
1.35


1.82
1.54
1.71
1.62
1.63
1.52
1.47
d


a
bc
ab
abc
abc
bc
c
1.58


NS
NS
*
*

NS
NS
NS
NS
bc *


1079 NS
1073

14.61%


9.06%


b
b







Table 2. Diagnostic
Corn
Cultivar


ear leaf tissue analysis for eight corn cultivars treated with a commercial chemical.
Manner i um


Nitrogen Phosphorus


Potassium Calcium


Sprayed


Unsprayed


---------------------------------- g kg-' ----------------------------------------


Howard III
Pioneer Brand X304C
FLASTOP
Pioneer Brand 3154
DeKalb 706
ICI 8105
ICI 8100
Asgrow RX949W

Spray Average
No Spray Average

CV =


28.7
28.5
30.0
32.8
31.3
27.7
28.8
28.9


c
c
c
a
ab
c
c
c


29.7 NS
29.5

6.15%

Copper


2.76
2.98
3.03
2.73
2.97
3.65
3.53
3.06


cd
bcd
bc
d
bcd
a
a
b


3.11 NS
3.06

6.04%


Iron


21.6
20.3
19.9
21.7
20.0
21.7
22.8
23.6


21.8 NS
21.1

7.41%


4.38 cd
6.93 a
6.48 ab
4.30 e
5.39 cd
5.74 bc
4.85 de
5.98 bc


5.45 NS
5.56

11.71%


1.29
1.76
1.47
1.12
1.21
1.26
1.29
2.00 a


d 1.38
b 1.79
c 1.30
d 1.06
d 1.36
d 1.50
d 1.38
2.16 a


9.00%


Manganese Zinc


------------------ mg kg -------------------


Howard III
Pioneer Brand X304C
FLASTOP
Pioneer Brand 3154
DeKalb 706
ICI 8105
ICI 8100
Asgrow RX949W

Spray Average
No Spray Average

CV =


9.6
10.3
6.5
9.5
11.8
11.8
12.3
12.1


10.7 NS
10.3

19.74%


c 81
bc 96
d 79
c 139
ab 83
ab 119
a 100
a 86


102 NS
94

25.87%


b


:d NS
NS
d NS
e NS
:d NS
- NS
:d NS
NS


43 b
62 a
34 b
43 b
34 b
43 b
43 b
49 ab

45 NS
43

42.23%


47 a
45 a
48 a
32 b
49 a
48 a
40 ab
42 a

44 NS
43

27.28%


Howard III, Florida experimental subtropical hybrid; Pioneer Brand X304C, tropical hybrid; FLASTOP, Florida
experimental subtropical population; Other corn are temperate hybrids. Values in columns among corn cultivars
not followed by the same letter are significantly different at the 0.05 level of probability according to
Duncan's multiple range test. NS = non significant at the 0.05 level of probability when comparing between
sprayed and unsprayed. CV = coefficient of variation.


- ------ i 1i ------ -- ---- _--n n e---s i u .._____ -- __ _






Table 3. Kjeldahl N, Mehlich I extractable elements, pH, CEC and organic matter for soil site of eight corn
cultivars treated with a commercial chemical.
Corn Nitrogen Phosphorus Potassium
Cultivar Plant Harvest Plant Harvest Plant Harvest


----------------------------------- mg kg-' ----------------------------

Howard III 512 bc 602 a 145 a 128 a 54 a 45 a
Pioneer Brand X304 C 605 a 611 a 140 a 125 a 67 a 52 a
FLASTOP 477 c 617 a 112 a 109 a 50 a 40 a
Pioneer Brand 3154 537 abc 572 a 161 a 126 a 65 a 49 a
DeKalb 706 611 a 607 a 131 a 97 a 51 a 47 a
ICI 8105 554 ab 591 a 167 a 120 a 63 a 35 a
ICI 8100 544 abc 573 a 116 a 92 a 48 a 38 a
Asgrow RX949W 569 ab 590 a 122 a 107 a 55 a 43 a

Spray Average 550 NS 593 NS 124 107 NS 54 NS 40 NS
No Spray Average 552 597 149 119 59 47

CV = 20.45% 13.79% 35.50% 46.00% 22.43% 27.26%

Calcium Magnesium Sodium
Plant Harvest Plant Harvest Plant Harvest


----------------------------------- mg kg'-------------------------------------


Howard III
Pioneer Brand X304 C
FLASTOP
Pioneer Brand 3154
DeKalb 706
ICI 8105
ICI 8100
Asgrow RX949W

Spray Average
No Spray Average

CV =


687
782
625
674
577
722
649
557


abc
a
bc
abc
bc
ab
abc
c


613 *
704

24.70%


727
848
756
893
743
850
666
715


690 *
858

30.33%


38 *


19.42%


50 *


23.31%


13.4
12.2
11.3
15.2
12.6
13.3
11.5
11.9


12.0 *
13.4

24.15%


16.0
13.7
13.3
11.8
11.3
11.5
10.5
13.1


12.9 NS
12.4

47.84%






Table 3. Continued

Corn Copper Iron Manganese
Cultivar Plant Harvest Plant Harvest Plant Harvest


---------------------------------- --mg kg-------------------------------------

Howard III 0.72 a 0.91 a 18.1 bc 14.1 a 10.8 a 10.0 a
Pioneer Brand X304 C 0.77 a 0.75 a 17.5 c 13.0 a 11.4 a 9.0 a
FLASTOP 0.73 a 0.51 a 16.6 c 12.8 a 7.9 a 7.2 a
Pioneer Brand 3154 0.79 a 0.62 a 20.3 a 13.0 a 10.9 a 8.4 a
DeKalb 706 0.59 a 0.57 a 19.7 ab 13.0 a 11.0 a 8.1 a
ICI 8105 1.13 a 0.61 a 19.5 ab 13.1 a 13.1 a 8.4 a
ICi 8100 1.20 a 0.62 a 16.7 c 12.6 a 10.0 a 7.5 a
Asgrow RX949W 0.72 a 0.62 a 18.1 bc 13.8 a 9.8 a 8.0 a

Spray Average 0.88 NS 0.65 NS 17.9 NS 13.2 NS 9.8 NS 7.9 NS
No Spray Average 0.78 0.66 18.8 13.1 11.4 8.7

CV = 57.08% 55.05% 13.47% 18.83% 33.18% 23.17%

Zinc CEC Organic Matter pH
Plant Harvest Plant Harvest Plant Harvest Plant Harvest


---- mg kg' ------ ---- meq 100g" ------ ------- g 100g -----

Howard III 6.7 b 5.9 a 5.79 ab 6.31 c 1.51 a 1.60 a 6.8 a 6.9 a
Pioneer Brand X304 C 6.0 b 6.7 a 6.49 a 7.67 a 1.71 a 1.96 a 6.5 c 6.5 a
FLASTOP 5.5 b 5.2 a 5.64 b 6.50 bc 1.59 a 1.71 a 6.7 ab 6.8 a
Pioneer Brand 3154 7.1 b 6.4 a 5.90 ab 7.58 ab 1.52 a 1.60 a 6.8 a 6.7 a
DeKalb 706 5.9 b 6.2 a 5.68 b 6.22 c 1.86 a 1.72 a 6.6 bc 6.8 a
ICI 8105 10.9 a 5.9 a 5.92 ab 6.99 abc 1.65 a 1.62 a 6.8 a 6.9 a
ICI 8100 5.2 b 5.0 a 5.41 b 5.96 c 1.58 a 1.60 a 6.8 a 6.8 a
Asgrow RX949W 4.8 b 4.7 a 5.10 b 6.37 c 1.53 a 1.62 a 6.7 ab 6.8 a

Spray Average 5.5 5.0 5.60 NS 6.32 1.58 NS 1.65 NS 6.7 NS 6.7 NS
No Spray Average 7.6 6.5 5.88 7.08 1.66 1.75 6.8 6.8

CV = 56.80% 50.42% 14.92% 17.05% 19.73% 30.33% 3.68% 4.62%

Howard III, Florida experimental subtropical hybrid; Pioneer Brand X304C, tropical hybrid; FLASTOP, Florida
experimental subtropical population; Other corn are temperate hybrids. Values in columns among corn cultivars
not followed by the same letter are significantly different at the 0.05 level of probability according to
Duncan's multiple range test. NS = non significant and significant at the 0.05 level of probability when
comparing between sprayed and unsprayed. CV = coefficient of variation.








Table 4. Effect of treatment with corn cultivar and commercial spray on population densities of ring
(Criconemella spp.), stubby-root (Paratrichodorus minor), lesion (Pratylenchus spp.) and root-knot (Meloidogyne
Incognita) nematodes.

Nematode
Corn Ring Stubby-root Lesion Root-knot
Cultivar 26 Apr 28 Jun 26 Apr 28 Jun 26 Apr 28 Jun 26 Apr 28 Jun

---------------------- Nematodes 100 cm"3 soil---------------------

Howard III 44 69 17 28 17 151 3 75 b
Pioneer Brand X304 C 38 47 18 27 15 138 2 208 a
FLASTOP 50 62 23 23 11 176 1 99 b
Pioneer Brand 3154 33 40 17 21 35 98 2 72 b
DeKalb 706 54 50 23 23 10 131 2 126 ab
ICI 8105 45 56 18 23 12 104 3 86 b
ICI 8100 64 98 12 28 15 90 2 148 ab
Asgrow RX949W 38 145 22 44 12 115 4 132 ab

Spray Average 56 65 NS 16 28 NS 14 138 NS 2 120 NS
No Spray Average 36 77 21 26 15 113 2 116

Data for corn cultivars are means of 10 replications, averaged across spray treatments. Data for spray or no
spray treatments are means of 40 replications, averaged across eight corn cultivars. Values in columns among
corn cultivars not followed by the same letter are significantly different at the 0.05 level of probability
according to Student-Newman-Keul's test; No letter in columns among corn cultivars indicate no significant
differences at the 0.05 level of probability. NS = no significant differences between spray treatments at the
0.05 level of probability.




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