Comparison of Corn Hybrids Grown at Several Locations in ...

Comparison of Corn Hybrids Grown at Several Locations in West Tennessee

A Research Paper Presented for the Master of Science in Agriculture and

Natural Resources Degree The University of Tennessee at Martin

Curtis W. Cochran May 2, 2014

ii

Copyright © 2014 by Curtis W. Cochran All rights reserved.

iii

Dedication

I would like to dedicate this research to my dad, Roger Cochran, and wife, Catelyn

Cochran, who have had a major part in it. My wife has always been there for me and helped

with anything that I may need. She has always been supportive and understanding through the

long hours of work. My dad has instilled in me the love of agriculture and the mindset to stay

ahead of the game. He sparked my interest in the technology and study of precision agriculture

and how it can be used. Without these two, this would not be possible.

iv

Acknowledgements

I would like to thank the faculty of the University of Tennessee at Martin Department of

Agriculture, Geosciences, and Natural Resources for their help in achieving everything I have

through the process. Dr. Darroch and Dr. Mehlhorn have been especially helpful throughout my

collegiate years and I am very grateful. My employer, Mason Hall Grain Company has also been

very helpful in providing resources and time that was needed for this research project. Most of

all, I would like thank my family who have helped me through all of the issues and have been

patient with the amount of time that this has taken.

v

Abstract

Selection of specific corn hybrids is becoming more important in West Tennessee each

year. With the technology that plant breeders have, new hybrids are being created specifically for

certain situations. Due to the cost of hybrid seed, it is vital that farmers select the correct hybrid

for each location to maximize yield. Research is required so farmers can access information on

hybrid performance in their area. This research project evaluated 12 corn hybrids grown at 16

locations in West Tennessee. Yield, percent moisture, and test weight were determined for each

hybrid. A randomized complete block design was used, with each location considered to be one

block. Hybrids were compared under irrigated and non-irrigated conditions; data were also

analyzed over all locations. Hybrid DKC 62-08 was the highest yielding in each environment,

both irrigated and non-irrigated locations. DKC65-19, 1133PRO2, and P1319HR were hybrids

that also yielded well in each environment and were not significantly different from DKC62-08.

1770 Pro was, on average, the lowest yielding hybrid, but was not significantly different from N7-

40J. Growing season conditions affect hybrid performance, but information from research and

demonstration trials like this one helps farmers choose the best variety that is available.

vi

Table of Contents

Chapter 1 ...........................................................................................................................................1

Introduction .....................................................................................................................................1

Objectives .......................................................................................................................................2

Chapter 2 ...........................................................................................................................................3

Literature Review ............................................................................................................................3

Importance of Corn .....................................................................................................................3

Corn Production in Tennessee ....................................................................................................3

History of Corn Hybrid Breeding ...............................................................................................4

Corn Breeding.............................................................................................................................5

Hybrid Placement ........................................................................................................................7

Irrigated vs Non-Irrigated ...........................................................................................................9

Chapter 3 .........................................................................................................................................11

Materials and Methods ..................................................................................................................11

Chapter 4 .........................................................................................................................................15

Results and Discussions ................................................................................................................15

Chapter 5 .........................................................................................................................................20

Conclusions and Recomendations ...............................................................................................20

List of References............................................................................................................................21

Appendix .........................................................................................................................................23

vii

List of Tables Table Page Table 1. Descriptions of the soil types found at the 13 locations used in this study ................................14

Table 2. Results of ANOVA for yield, moisture, and test weight of corn hybrds ..........................16

Table 3. Least square means for yield, moisture, and test weight of 12 corn hybrids, averaged

over 13 locations in west Tennessee in 2013 ...................................................................................17


over four irrigated locations in west Tennessee in 2013 ..................................................................18


over nine non-irrigated locations in west Tennessee in 2013 ...........................................................19

Table A.1. Results of ANOVA for yield using all locations ..........................................................23

Table A.2. Results of ANOVA for moisture using all locations ....................................................23

Table A.3. Results of ANOVA for test weight using all locations ................................................23

Table A.4. Results of ANOVA for yield using irrigated locations ................................................24

Table A.5. Results of ANOVA for moisture using irrigated locations ..........................................24

Table A.6. Results of ANOVA for test weight using irrigated locations .......................................24

Table A.7. Results of ANOVA for yield using non-irrigated locations .........................................25

Table A.8. Results of ANOVA for moisture using non-irrigated locations ...................................25

Table A.9. Results of ANOVA for test weight using non-irrigated locations ................................25

Table A.10. Results of Lsmeans procedures for yield of corn hybrids averaged over all

locations ...........................................................................................................................................26

Table A.11. Results of Lsmeans procedures for moisture of corn hybrids averaged over all

locations ...........................................................................................................................................27

viii

Table A.12. Results of Lsmeans procedures for test weight of corn hybrids averaged over all

locations ...........................................................................................................................................28

Table A.13. Results of Lsmeans procedures for yield of corn hybrids averaged over irrigated

locations ...........................................................................................................................................29

Table A.14. Results of Lsmeans procedures for moisture of corn hybrids averaged over

irrigated locations ............................................................................................................................30

Table A.15. Results of Lsmeans procedures for test weight of corn hybrids averaged over

irrigated locations ............................................................................................................................31

Table A.16. Results of Lsmeans procedures for yield of corn hybrids averaged over

non-irrigated locations .....................................................................................................................32

Table A.17. Results of Lsmeans procedures for moisture of corn hybrids averaged over

non-irrigated locations .....................................................................................................................33

Table A.18. Results of Lsmeans procedures for test weight of corn hybrids averaged over

non-irrigated location ......................................................................................................................34

ix

List of Figures Figure Page Figure 1. Twelve corn hybrids were tested at 13 locations in 2013 ................................................12

Figure 2. Corn hybrids were planted at 13 locations in west Tennessee in 2013 ............................13

Figure 3. Temperatures recorded at Dyersburg, TN during growing season in 2013 .....................15

x

1

Chapter 1

Introduction

Corn (Zea mays L.), also known as maize, originated in Mexico (Brown et al., 1985).

Hybrid corn is the most popular crop grown for grain in the state of Tennessee. Corn acreage

ranges from year to year at 700,000-900,000 acres (NASS, 2013). The northwest Tennessee area

is the largest producing area in Tennessee, with the top counties being Obion, Weakley, and

Gibson (NASS, 2013).

There is a lot more to the development of corn hybrids than many realize. Potential

varieties go through rigorous testing before they are ever made available for sale. Only the best of

the best hybrids make it through all the way to the retail store. Hybrids offered for sale must have

the genetics needed to maximize yields under specific conditions. Some hybrids will need more

insect resistance and others will need more drought resistance depending on the environment in

which they will be grown. Maturity requirements also vary with location. It is up to individual

farmers to do the research to find out which varieties fit their farm best. Irrigation also has an

effect on what varieties should be planted. Certain varieties are bred with the intention of being

used under irrigation. These hybrids require additional water but produce huge yields for the

farmer (Thomison, 2012). Varieties such as this normally do not do well in dry land areas due to

their large need for water. Corn hybrids are continually changing and it is important for farmers to

do their research so that they can maximize yields based on available corn hybrids (Thomison,

2012).

2

Objectives

This research project evaluated corn hybrids to see which variety performs the best in each

situation. Specifically, the research objectives were to determine:

1) What corn hybrids performed best in west Tennessee?

2) Which corn hybrids yield better under irrigation or dry land conditions?

3

Chapter 2

Literature Review Importance of Corn:

There were over 97.2 million acres of corn planted in the U.S. in 2012 (NCGA, 2014).

Corn was first grown for food approximately 10,000 years ago; Dr. George W. Beadle determined

that corn originated from teosinte, a Mexican native grass (Carroll, 2010). With the recent demand

for alternative energy sources the need for corn has increased. Farmers must find ways to

maximize yield on every acre. This is especially vital in the U.S. where the largest amount of corn

is produced (Kelly, 2006). The largest corn producing countries in 2013 were the U.S. which

produced 13.9 trillion bushels, China, which produced 8.5 trillion bushels, and Brazil, which

produced 3.2 trillion bushels (NCGA, 2014). The largest corn producing states in the U.S. in 2012

were Iowa, which produced 1.8 trillion bushels, Minnesota, which produced 1.3 trillion bushels,

and Illinois, which produced 1.2 trillion bushels (NCGA, 2014).

Corn Production in Tennessee:

The most important grain crop grown in Tennessee is corn. From 700,000 to 900,000 acres

of corn are grown in Tennessee per year (NASS, 2013). In 2013, the largest corn-producing

counties in Tennessee were Obion, which produced 11.3 million bushels, Gibson County, which

produced 9.8 million bushels, and Weakley County, which produced 9.1 million bushels (NASS,

2013). All three counties are located in northwest Tennessee, making it the largest corn producing

region in the state. The total numbers of acres farmed in corn now is only one quarter of the acres

used to produce corn in the 1930s (NCGA, 2014). The average yield then was about 23 bushels

4

per acre but, by 2012, the Tennessee average was 85 bushels per acre (NCGA, 2014). Even though

2012 was a dry year, the average yield was still over 60 bushels more per acre than in the 1930s.

In 2013, corn yields in the state averaged 156 bushels per acre (NASS,2013).

The time frame for planting corn in Tennessee ranges from late March until mid May.

Depending on the land, seeding rate varies from 26,000-32,000 seeds per acre on dry land farms.

A seeding rate of 34,000 seeds per acre is sometimes used on irrigated land (Flinchum, 2001).

Fertilizers such as phosphorous and potash are applied according to recommendations from soil

tests. Nitrogen is applied to dry land farms on a basis of 1.1 lbs N per bushel of expected yield.

Irrigated farms use nitrogen more efficiently and therefore do not require as much per bushel

(McClure, 2012). In Tennessee, corn is generally harvested between August and October.

History of Corn Hybrid Breeding:

Being able to understand the history of the corn plant is important for breeders. Of the

documented background of hybrid corn in the U.S., 51% comes from Reid Yellow Dent (Troyer,

2004). Lancaster Sure Crop and Minnesota 13 both make up 13%, whereas Learning Corn and

Northwestern Dent make up 5% each. These five open pollinated varieties, which are over 100

years old, account for 87% of the known hybrid corn background in the U.S. They have been used

in thousands of hybrids. In 1840, farmers had about 250 open pollinated varieties to choose from

(Mikel, 2008). Hybrid corn replaced the open pollinated varieties by the 1930s. Single cross

hybrids were commercialized in the 1960s and are still used today (Mikel, 2008). Corn breeders

continue to develop new hybrids making them better adapted to climate changes and soil

variability. Each new hybrid and inbred line gives breeders the ability to make more unique

5

hybrids (Troyer, 2004). About half of the yield improvement over the years is directly related to

improved hybrids and the other half to improved agronomic practices (Mikel, 2008).

Corn hybrid breeding was first started around 1909 by Dr. G.H. Shull (Hallauer et al.,

1988). In 1908, Shull reported that there were issues with inbred corn plants that were improved

with crossbreeding. E.M. East was also researching hybrids at the time but thought that the cost of

cross bred hybrids was too much to make it worthwhile (Crow, 1998). Graduate student D.F.

Jones used this information to advocate double cross hybrids. This was done by crossing two

previously crossed hybrids, which produced enough seed to make the idea practical. These

findings eventually led to the first commercial sale of hybrid corn seed by Henry A. Wallace

(Crow, 1998). By 1926, Henry Wallace had used Dr. Shull’s studies to start the first corn

breeding company called Hi-Bred Corn Company (Pioneer, 2014). This company has evolved and

is now known as Pioneer Hi-Bred International, one of the world’s largest corn breeding

companies. Breeding corn hybrids gave Henry Wallace the same hope when he started researching

it that it does farmers today, which is the hope of creating the perfect hybrid for each situation.

The goal of breeding hybrid corn is to make the plant bigger, stronger, and more adaptive to the

climate. Technology continues to give researchers the ability to take more steps to improve the

hybrids that are in place today.

Corn Breeding:

One of the most important steps of plant breeding is the research involved to find out what

needs to be changed about the current hybrids. Since corn breeding really got going in the 1950s,

corn yields have increased nearly 2 bushels per acre every year (Pioneer, 2014). The science of

genomics studies the functions of corn genes. This gives researchers the ability to better understand

6

how each gene will react to different environments (Pioneer, 2014). C. W. Stuber, a plant

geneticist, found that knowledge of the genetic makeup of corn could allow breeders to be more

precise when deciding which plants to breed to increase yield (Lee, 1996). With advances in

biotechnology, researchers are able to get a better understanding of genes being used to create

hybrids. Knowing how plants work and what specific genes will do helps corn breeders develop

high yielding hybrids. Certain genes will protect against diseases and others will fight drought or

cold weather, for example (Thomison, 2012). The most widely used method for developing inbred

lines from parent hybrids is the pedigreed method (Hallauer et al., 1988). Pioneer uses a tool

known as transformation to take genes from an outside source and put them into corn hybrids

(Pioneer, 2014). This was done recently when a gene resistant to insects was integrated into a

hybrid.

Each region needs different characteristics within corn hybrids to suit the local

environment. Some areas need a corn hybrid that will do well in a hot and dry climate, whereas

another region may need one that will do better in a milder climate. Researchers combine genes

from two different hybrids that each have good traits but are lacking in some areas. The yield gain

in hybrids compared to their inbred parents it is known as heterosis (Flavell, 2010). Heterosis

basically describes the superiority of a hybrid over its parents. The results of heterosis have not

changed over the years (Tollenar et al., 2004). The idea is to cross two inbred corn lines with the

hope that the new hybrid will be better than the parents.

The male part of the plant, called the tassel, is located at the top of the corn plant; it

produces the pollen. The silks, located on the top of the ear, trap the pollen that will combine with

the ovules to produce seed. Each silk, is connected to an ovary that has the ability to produce one

7

kernel of corn (Pioneer, 2014). When a plant fertilizes itself with its own pollen it is known as self

pollination. Cross pollination (when a plant is pollinated with pollen from another plant) is

essential to produce hybrids. Corn breeders take the pollen from one inbred line and place it on the

silks of a second line to create hybrid seed.

The first step in hybrid production is creating inbred lines. Elite parent varieties are self

pollinated for several germinations to produce inbreds. Some breeders will use only 2 or 3

generations of in-breeding with subsequent reproduction by sibmating within progenies. This will

produce hybrids that may yield more but lack genetic stability (Hallauer et al., 1988). With each

generation, plant breeders select the best inbred lines to carry forward (Pioneer, 2014). Once this

step is finished, the researchers begin determining which parent inbred lines will perform best

during crossbreeding. Pioneer tests about 130,000 new hybrids each year. They select the best

hybrids from initial testing and continue to evaluate these. With each selection cycle, the number

of hybrids is reduced and the evaluation tests become more wide spread and extensive. By the

time the final 15-20 hybrids are selected, they have been through tests at more than 1500 locations

and in more than 200 customer fields before they are offered for commercial sale (Pioneer, 2014).

Researchers must find traits that will produce in the inbreds as well as the cross breds. The goal is

to create hybrids that yield well for farmers (Pioneer, 2014).

Hybrid Placement:

Corn varieties vary more and more with each year of research and breeding.

Demonstration plots are becoming more important with the technology in place today. Companies

are changing genetic traits more frequently and farmers want to know what is going to work under

specific conditions. With the cost of seed, it is important to efficiently manage the farm and

8

variety placement goes a long way toward improving profitability (Smit et al., 1997). Farmers

have to decide whether or not to take a risk and go for the extremely high potential varieties that

require all growing conditions to be perfect or to be more conservative. Because there is no way to

accurately forecast exactly what the growing season will be like, it is important that the farmer

know the capability of his land. Varieties that require less heat units are normally going to have

less yield potential than hybrids that require more heat units (Smit et al., 1997). Heat units refer to

the amount of heat a hybrid requires to completely mature. Hybrids that need more heat units

require longer growing seasons, which increases the potential for bad weather that could hurt

yields (Smit et al., 1997). The problem is not knowing what the weather will do from year to year

(Smit et al., 1997).

Being able to place the correct corn hybrid in the best location is important and requires

research. With the cost of corn seed it is imperative that yield be maximized. First, farmers must

select a variety within the maturity range for their area. Normally the goal for corn is for it to reach

physical maturity at least one week before the first hard frost in the fall (Thomison, 2008). Even

though full season hybrids normally yield better than shorter season hybrids, a full season hybrid

that does not mature completely before frost will not yield as much as a mature shorter season

hybrid. Location and when the crop is planted both affect choice of hybrid maturity. It is also

smart to plant different maturing varieties on a farm. Farmers should plant the longer season

hybrids first and gradually decrease the maturity levels through the planting season. Farmers

should select varieties that are known for getting a good stand at planting as well as at maturation.

Some varieties are known to yield high but can be prone to lodging. Lodging problems can be

9

avoided by farmers who have drying facilities; they can harvest earlier and dry the seed after

harvest (Thomison, 2008).

Finding one hybrid that will produce high yields in any environment every year is rare.

One variety could be best on hilly dry land areas, while the next could do best on a wet bottom

farm. Some varieties are more susceptible to certain diseases as well; this must be considered,

especially when a disease is common in the area in which the variety is to be planted. Certain

hybrids are also bred to be resistant against pests such as rootworm. Looking at results from corn

hybrid test plots can greatly improve product placement for farmers (Thomison, 2008).

Irrigated vs Non-Irrigated:

Soil type is an important consideration for both irrigated and dry land production. Some

soil types are capable of producing more than others. It is crucial to know the type of soil on

which irrigation is taking place. Certain soils can hold more water than others, which changes the

schedule of watering. Sandy soils do not hold as much water and will need to be irrigated more

frequently than clays and silts (Kranz et al., 2008). Corn stress due to insufficient water is the worst

during the reproductive phase of development (Gordon et al., 1995). Variable rate planting can also

be important. Corn can be planted at a higher rate on certain soil types or when irrigation is used

than under dry land conditions (Kranz et al., 2008).

A farm that has irrigation must be managed in a completely different way than one that

does not. Using an irrigation system is not as simple as just turning it on and watering the plants.

Timing is a major component of efficient irrigation use (Gordon et al., 1995). Soil can hold only a

certain amount of water before it becomes saturated; this can harm the plant by reducing the

10

amount of oxygen available (He et al., 2003). In the very hot and dry times of the year it is better

to irrigate during the night when it is cooler and not as much water is lost to evaporation. There

are certain times in the life of a plant when it needs more water than others (Kranz et al., 2008).

Hybrid placement can play a role in irrigation management. It is important for farmers to select

hybrids that have produced very high yields in trials. Farmers should chose hybrids that yielded at

least 90 percent of the highest yielding variety in the trials (Sylvester,2012).

Non irrigated crop land must be managed as carefully as irrigated land. Changing the

planting rate of corn is a little more important for dry land farming to maximize the potential of

every acre of a farm. Not having irrigation will also change the varieties planted on the farm

(Kranz et al., 2008).

11

Chapter 3

Materials and Methods

This project was completed in cooperation with Mason Hall Grain Company and 13

farmers who provided the land. The research compared 12 corn hybrids (Figure 1) planted at 13

locations in west Tennessee (Figure 2). These trial locations included 16 soil series across west

Tennessee (Table 1). Soil samples were taken at each site to determine what nutrients needed to be

applied. A randomized complete block design was used with each location comprising one block.

The plots were planted with each farmer’s personal planter between April 3 and May 30, 2013 and

harvested between September 5 and November 4, 2013. The planting population at each location

ranged from 30,000 – 34,000 seeds per acre. Fertilizer was applied according to recommendations

from soil tests. Four locations were irrigated and the other nine were not. The plots were

monitored during the growing season and notes were made accordingly. At the time of harvest,

seed from each variety was weighed to calculate yield. The moisture and test weight were

calculated with a calibrated Steinlite moisture meter. ANOVA and Lsmeans were calculated using

SAS (SAS Institute Inc., Carry, NC) to determine the differences among means.

12

Figure 1. Twelve corn hybrids were tested at 13 locations in 2013.

13

Figure 2. Corn hybrids were planted at 13 locations in west Tennessee in 2013

14

Table 1. Descriptions of the soil types found at the 13 locations used in this study

Soil Type Map Symbol Soil Description

Adler silt loam Ad Moderately well drained soil on first bottoms

Calloway silt loam Ca Somewhat poorly drained soil on gently 0-3% sloping hillsides. Fragipan approx. 20" below surface

Center silt loam Ce Somewhat poorly drained soil on slight ridges on broad, flat uplands (0-2% slopes)

Collins silt loam Cl Deep, moderately well drained soil in first bottoms, 0-2% slopes; floodwater hazard in early spring

Commerce silt loam Cm Somewhat poorly drained soil on river bottoms; slopes 0-2%; texture is mostly clay

Dekovan silt loam Dk Dark colored, poorly drained soil; slopes 0-2%; water table near surface during wet springs

Dekovan (overwash) Do Bottom soil with surface layer of very friable silt loam washed from surrounding uplands

Falaya silt loam Fa Flat somewhat poorly drained soil on first bottoms along rivers and streams

Fountain silt loam Fn Poorly drained soil on broad flats; mostly in Houser valley and on adjacent "flat land"; slopes 0-2%

Grenada silt loam GrB Modeately well drained soil mostly on ridgetops; fragipan approx. 24" below surface; slopes 2-5%

Grenada silt loam GrC Slopes 5-8%

Loring silt loam LoB Deep, moderately well drained soil on ridgetops with fragipan 30" below surface; 2-5% slopes

Loring silt loam LoC 5-8% slopes

Memphis silt loam MtB Deep well drained soil in hills at edge of Misissippi River bottoms; 2-5% slopes

Routonsilt loam Rt Gray, poorly drained soil in low, flat uplands; "Buckshot land" or "white land"; 0-2% slopes

Waverly sil loam Ws Flat, poorly drained soil on broad first bottoms along smaller streams

15

Chapter 4

Results and Discussion

The weather conditions for the 2013 growing season were very good for the corn crop.

There was an above average amount of rainfall and temperatures were close to average (Figure 3);

therefore, there was little, if any, heat damage. As a result, the non-irrigated corn yields were

closer than normal to the irrigated corn yields in 2013.

The results of the trials gave us information that can be helpful for many years. The

analysis of variance showed significant differences among the hybrids and blocks, both when all

blocks were combined and when irrigated and non-irrigated sites were analyzed separately

(Table 2).

Figure 3. Temperature as recorded at Dyersburg, TN during growing season in 2013.

16

Table 2. Results of ANOVA for yield, moisture and test weight of corn hybrids. Analysis was conducted for all blocks (locations) and separately for irrigated locations and non-irrigated locations.

Sites use in Analysis Pr>F

Hybrid Block

All Yield < 0.0001 < 0.0001 Moisture < 0.0001 < 0.0001

Test Weight < 0.0001 < 0.0001

Irrigated Yield 0.0005 0.0026 Moisture < 0.0001 < 0.0001

Test Weight < 0.0001 0.0001

Non-Irrigated Yield 0.0012 < 0.0001

Moisture < 0.0001 < 0.0001

Test Weight < 0.0001 < 0.0001

When looking at all plots, there were significant differences among hybrids for yield, moisture, and

test weight. Block effects were also significant, reflecting the differences among the blocks

(locations). Least square means (LSMeans) were calculated for all hybrids to find significant

differences among the hybrids.

Table 3 shows the differences in mean yield, percent moisture, and test weight for each

hybrid averaged over all 13 locations that were used in the research. DKC 62-08, DKC 65-19,

1133PRO2, and P1319HR had the best yields across locations. However, three other hybrids

(DKC66-40, N785-311, and P1636YHR) had the next highest yields, and their mean yields were

not significantly different from three of the top four hybrids. For moisture, 1023AM-R,

1133PRO2, and P1636YHR had the lowest percent moisture at harvest. The hybrids with the

highest test weight were DKC65-19, P1319HR, and P1636YHR. This shows what the farmer can

expect from each variety when not considering the exact environment and only looking at the west

Tennessee region. Hybrids such as 1770-PRO and N78S-311 had high moisture contents at

17

Table 3. Least square means for yield, percent moisture, and test weight of 12 corn hybrids, averaged over 13 locations in west Tennessee in 2013

Hybrid Yield(Mt/ha) Moisture (%) Test Weight (Kg/hL)

DKC62-08 13.6a† 17.4cde 73.8b

DKC65-19 13.1ab 18.2ef 75.1a

1133PRO2 13.1ab 16.8ab 73.4bc

P1319HR 13.1ab 17.5de 75.8a

DKC66-40 12.8bc 18.3ef 73.4b

N78S-311 12.7bc 19.2f 69.8f

P1636YHR 12.7bc 16.9abc 75.2a

1555-SS 12.4cd 18.7ef 73.4bc

1023AM-R 12.3cd 16.5a 72.5de

N74G-300 12.3cd 17.7de 72.6cde

N70J-401 11.9d 17.2bcd 73.2bcd

1770-PRO 11.7d 18.9f 71.9e † Within a column, means followed by the same letter are not significantly different

(according to the Pdiff option of the Lsmeans procedure in SAS. P ≤ 0.05)

harvest, which led to lower test weights. These longer season hybrids did not dry down as much

before harvest, thus affecting their test weights. A later harvest may have helped these hybrids

yield better.

Under irrigated conditions, all of the hybrids except 1023AM-R, 155SS, 1770-PRO, and

N70J-401 were high yielding and not significantly different from each other (Table 4). However,

the four lowest-yielding hybrids had yields that were not significantly different from yields

produced by DKC66-40. Therefore it is hard to differentiate among all of the hybrids tested. The

main reason for them being so close in yield is that under nearly ideal conditions such as

irrigation most hybrids will maximize their yield. Any of the top yielding hybrids would be a

good choice for irrigated lands when looking at yield. For moisture content, 1023AM-R had a

significantly higher moisture content than all other hybrids. The hybrids with the highest test

18

Table 4. Least square means for yield, percent moisture, and test weight of 12 corn hybrids averaged over four irrigated locations in west Tennessee in 2013. Hybrid Yield(Mt/ha) Moisture (%) Test Weight (Kg/hL)

DKC62-08 14.7a† 17.1bc 74.1abcd P1319HR 14.6a 17.4bcd 75.6a DKC65-19 14.5a 17.9bcd 75.6a P1636YHR 14.5ab 16.8b 75.0ab 1133PRO2 14.1abc 16.7b 73.1cde N74G-300 13.9abc 17.2bcd 78.2e N78S-311 13.9abc 18.8e 70.3f DKC66-40 13.6abcd 18.7e 73.5bcde 1023AM-R 13.6bcd 15.7a 72.5de 1555-SS 13.5cd 18.1de 74.7abc 1770-PRO 12.8d 18.8e 72.8de

N70J-401 12.7d 16.8b 73.4bcde †Within a column, means followed by the same letter are not significantly different (according to the Pdiff option of the Lsmeans procedure in SAS. P ≤ 0.05)

weight were DKC65-19, P1319HR, DKC62-08, 1555-SS and P1636YHR. This shows what

farmer can expect in west Tennessee from each hybrid when considering planting acres that will

be under irrigation.

Table 5 shows the differences in yield, percent moisture, and test weight for each hybrid

averaged over the nine non irrigated locations that were used in the research. DKC62-08,

1133PRO2, DKC65-19, P1319HR, and DKC66-40 were the highest yielding hybrids, on

average, on the non irrigated plots. Any one of these five hybrids would be a good choice for

planting on non irrigated farms. However, there were other hybrids with yields that were not

significantly different from the yields of some of the top five. The hybrids that had the lowest

percent moisture were 1133PRO2, P1636YHR, 1023AM-R, and N70J-401. These are the

hybrids the farmer can rely on to dry down and mature earlier. P1319HR and P1636YHR were

the hybrids with the highest test weight in the non-irrigated environment.

19

Table 5. Least square means for yield, percent moisture, and test weight of 12 corn hybrids, averaged over nine non irrigated locations in west Tennessee in 2013. Hybrid Yield(Mt/ha) Moisture (%) Test Weight (Kg/hL)

DKC62-08 13.1a† 17.55bc 73.7c 1133PRO2 12.7ab 16.8a 73.5cd DKC65-19 12.5abc 18.4de 74.9b P1319HR 12.4abcd 17.5bc 75.8a DKC66-40 12.3abcde 18.2d 73.4cd N78S-311 12.2bcde 19.4f 69.6f 1555-SS 11.8cdef 19.0ef 72.8cd P1636YHR 11.8cdef 16.9a 75.3ab 1023AM-R 11.7cdef 16.9ab 72.5d N74G-300 11.6def 17.9cd 72.8cd N70J-401 11.5ef 17.4abc 73.1cd

1770-PRO 11.3f 19.0ef 71.4e †Within a column, means followed by the same letter are not significantly different (according to the Pdiff option of the Lsmeans procedure in SAS. P ≤ 0.05)

When comparing the results of the irrigated and non-irrigated locations, a farmer can see

which hybrids to choose for their farms. For example, P1636YHR yielded very well in the

irrigated but did not do well in the non-irrigated sites. With this information, the farmer can make

the decision to only plant the 1636YHR on the irrigated farms if possible. DKC 66-40 did well

under the non-irrigated conditions but not as well compared to some hybrids on the irrigated sites.

Several hybrids yields well under both irrigated and non-irrigated conditions. Good growing

conditions and above average rainfall during the 2013 growing season likely resulted in fewer

differences between irrigated and non-irrigated sites. Farmers must consider results from other

growing seasons, if available, when making their selections of corn hybrids for dryland conditions.

Even so, choosing hybrids that consistently produce well under all conditions may be the best

course of action for farmers (Thomison, 2012).

20

Chapter 5

Conclusions and Recommendations

The research and development that goes into the production of corn hybrids is second to

none. Of the thousands of varieties that are included in preliminary tests, only a few of the best are

used for retail. Trials such as the current study provide information on available corn hybrids so

farmers can determine which varieties might be best for them based on soil, irrigation, and

location. Farmers need to plant the correct varieties to maximize yield in each field. This study

showed what varieties performed best in west Tennessee under both irrigated and non-irrigated

environments. DKC 62-08, DKC 65-19, 1133PRO2, and P1319HR yielded well under all

conditions. Three other hybrids (DKC66-40, N785-311, and P1636YHR) had the next highest

yields, and their mean yields were not significantly different from three of the top four hybrids.

For irrigated land, the best yielding hybrids were DKC 62-08, DKC 65-19,1133PRO2, P1636YHR,

N74G-300, N78S-311, DKC66-40 and P1319HR. However, the remaining four hybrids had yields

that were not significantly different from the yields produced by DKC66-40. The best hybrids

when considering yield on non irrigated land were P1319HR, DKC 62-08, 1133PRO2, DKC65-19,

and DKC 66-40, but there were other hybrids with yields that were not significantly different from

the yields of some of these top five. These results show the best yielding corn hybrids for west

Tennessee, although sometimes it is difficult to determine the absolute best when there are no

statistical differences among many hybrids. Determining the best hybrid for every situation is the

goal of researchers as well as farmers.

21

List of References Brown, W. L., Zuber, M. S., Darrah, L. L., and Glover, D.V. 1985. Origin, adaptation, and types of

corn. National Corn Handbook. Iowa State University Cooperative Extension Service. https://corn.agronomy.wisc.edu/Management/pdfs/NCH10.pdf (accessed 14 Apr. 2014).

Carroll, S. B. 2010. Tracking the ancestry of corn back 9,000 years. Science. The New York Times. http://www.nytimes.com/2010/05/25/science/25creature.html?_r=0 (accessed 14 Apr. 2014).

Crow, J.F. 1998. 90 years ago: The beginning of hybrid maize. Genetics 148: 923-928. Flavell, R. 2010. From genomics to crop breeding. Nat. Biotechnol. 28: 144-145.

Flinchum, W.T. 2001. Corn production in Tennessee. Agriculture Extension Service. The University of Tennessee. http://webcache.googleusercontent.com/search?q=cache:OR1M08kdGaEJ:https://utexten sion.tennessee.edu/publications/Documents/PB443.pdf+&cd=1&hl=en&ct=clnk&gl=us (accessed 14 Apr. 2014).

Gordon, W.B., Raney, R.J., and Stone, L.R. 1995. Irrigation management practices for corn production in north central Kansas. J. Soil Water Conserv. 50: 395.

Hallauer, A.R., Russell, W.A., and Lamkey, K.R. 1988. Corn breeding. Corn and Corn Improvement. 18:463-564.

He, X., Vepraskas, M.J., Lindbo, D.L., and Skaggs, R.W. 2003. A method to predict soil saturation frequency and duration from soil color. Soil Sci. Soc. Am. J. 67: 961-969.

Kelly, J. 2006. How will corn find the acres it needs? Corn and Soybean Digest. 66: 40.

Kranz, W.L., Irmak, S., van Donk, S. J., Yonts, C.D., and Martin, D. L. 2008. Irrigation management for corn. NebGuide. University of Nebraska-Lincoln Extension. www.ianrpubs.unl.edu/live/.../g1850.pdf (accessed 14 Apr. 2014).

Lee, J. 1996. Precision breeding makes better corn—faster. Agric. Res. 44: 4-6.

McClure, A. 2012. Corn crop-next step nitrogen. UTcrops News Blog. The University of Tennessee Institute of Agriculture. http://news.utcrops.com/2012/04/corn-crop-next-step-nitrogen/ (accessed 14 Apr. 2014).

Mikel, M. A., 2008. Genetic diversity and improvement of contemporary proprietary North American dent corn. Crop Sci. 48: 1686-1695 (accessed 25 Apr. 2014)

22

National Agricultural Statistics Service (NASS). 2013. United States Department of Agriculture. http://www.nass.usda.gov/Statistics_by_State/Tennessee/Publications/County_Estimates (accessed 15 Apr. 2014).

National Corn Growers Association (NCGA). 2014. World of Corn. http://www.ncga.com/ upload/files/documents/pdf/woc-2014.pdf (accessed 25 Apr. 2014).

Pioneer Hi-Bred International, Inc. 2014. Developing a superior maize hybrid. www.pioneer.com/ CMRoot/.../maize_hybrid.pdf (accessed 14 Apr. 2014).

Smit, B., Blain, R., and Keddie, P. 1997. Corn hybrid selection and climatic variability: Gambling with nature? Can. Geo. 41: 429-438.

Sylvester, P. 2012. Maximizing irrigated corn yields in 2012. Cooperative Extension Kent County Agriculture. University of Delaware College of Agriculture & Natural Resources. https://extension.udel.edu/kentagextension/2012/02/27/maximizing-irrigated-corn-yields-in-2012/ (accessed 25 Apr. 2014).

Thomison, P. 2008. Key steps in corn hybrid selection. Agriculture and Natural Resources Fact Sheet. The Ohio State University Extension. https://ohioline.osu.edu/agf-fact/pdf/0125.pdf (accessed 14 Apr. 2014).

Thomison, P. 2012. Choosing corn hybrids for 2013. C.O.R.N. Newsletter 2012-40. The Ohio State University Extension. http://corn.osu.edu/newsletters/2012/2012-40/#1 (accessed 25 Apr. 2014).

Tollenar, M., Ahmadzadeh, and Lee, E.A. 2004. Physiological basis of heterosis for grain yield maize. Crop Sci. 44: 2086-2094.

Troyer, A. F. 2004. Background of U.S. hybrid corn II: Breeding, climate, and food. Crop Sci. 44: 370-380.

23

Appendix

Table A.1 Results of ANOVA for yield using all locations

Source of Degrees of Sum of Mean

Variation Freedom Squares Square F Value Pr>F

Block 11 39.721519 3.610138 5.80 <0.0001 Hybrid 12 496.6210459 41.3850872 66.44 <0.0001 Error 122 75.9892632 0.6228628

Total 143 613.6944272 Table A.2 Results of ANOVA for moisture using all locations




Total 143 636.8991781 Table A.3 Results of ANOVA for test weight using all locations




Total 143 802.921661

24

Table A.4 Results of ANOVA for yield using irrigated locations



Block 11 19.93546988 1.81231544 4.45 0.0005 Hybrid 3 7.19723404 2.39907801 5.89 0.0026 Error 31 12.625883 0.40728655

Total 45 40.13017417 Table A.5 Results of ANOVA for moisture using irrigated locations




Total 45 136.0521739 Table A.6 Results of ANOVA for test weight using irrigated locations



Block 11 105.7765152 9.6160468 8.00 <0.0001 Hybrid 3 34.6354167 11.5451389 9.61 0.0001 Error 31 37.2395833 1.2012769

Total 45 178.0230978

25

Table A.7 Results of ANOVA for yield using non irrigated locations



Block 11 25.4430468 2.3130043 3.21 0.0012 Hybrid 8 385.1351916 48.1418989 68.74 <0.0001 Error 80 57.7060154 0.7213252

Total 99 472.4257548 Table A.8 Results of ANOVA for moisture using non irrigated locations




Total 99 492.2304 Table A.9 Results of ANOVA for test weight using non irrigated locations




Total 99 621.875

26

Table A.10 Results of Lsmeans procedure for yield of corn hybrids averaged over all locations

Variety metyield LSMEAN LSMEAN Number

DKC62-08 13.5706915 1

DKC65-19 13.1283285 2

1133PRO2 13.0840217 3

P1319HR 13.0589631 4

DKC66-40 12.7462058 5

N78S-311 12.7208654 6

P1636YHR 12.6451431 7

1555-SS 12.3475592 8

1023AM-R 12.2931497 9

N74G-300 12.2871035 10

N70J-401 11.8565700 11

1770-PRO 11.7351747 12

Least Squares Means for effect Variety Pr > |t| for H0: LSMean(i)=LSMean(j)

Dependent Variable: metyield

i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 0.1649 0.1268 0.1009 0.0150 0.0070 0.0034 0.0001 0.0001 <.0001 <.0001 <.0001

2 0.1649 0.8913 0.8270 0.2623 0.2006 0.1296 0.0151 0.0131 0.0102 0.0001 <.0001

3 0.1268 0.8913 0.9370 0.3238 0.2536 0.1682 0.0216 0.0181 0.0152 0.0002 <.0001

4 0.1009 0.8270 0.9370 0.3510 0.2769 0.1838 0.0233 0.0199 0.0162 0.0002 <.0001

5 0.0150 0.2623 0.3238 0.3510 0.9397 0.7628 0.2351 0.1965 0.1786 0.0088 0.0044

6 0.0070 0.2006 0.2536 0.2769 0.9397 0.8072 0.2302 0.1901 0.1732 0.0061 0.0029

7 0.0034 0.1296 0.1682 0.1838 0.7628 0.8072 0.3383 0.2804 0.2604 0.0121 0.0059

8 0.0001 0.0151 0.0216 0.0233 0.2351 0.2302 0.3383 0.8672 0.8489 0.1153 0.0616

9 0.0001 0.0131 0.0181 0.0199 0.1965 0.1901 0.2804 0.8672 0.9855 0.1811 0.1028

10 <.0001 0.0102 0.0152 0.0162 0.1786 0.1732 0.2604 0.8489 0.9855 0.1764 0.0986

11 <.0001 0.0001 0.0002 0.0002 0.0088 0.0061 0.0121 0.1153 0.1811 0.1764 0.7090

12 <.0001 <.0001 <.0001 <.0001 0.0044 0.0029 0.0059 0.0616 0.1028 0.0986 0.7090

27

Table A.11 Results of Lsmeans procedure for moisture of corn hybrids averaged over all locations

Variety Moisture LSMEAN LSMEAN Number

1023AM-R 16.4730230 1

1133PRO2 16.7941665 2

P1636YHR 16.8615385 3

N70J-401 17.2384615 4

DKC62-08 17.3846154 5

P1319HR 17.4923077 6

N74G-300 17.6787121 7

DKC65-19 18.2203788 8

DKC66-40 18.2690330 9

1555-SS 18.7153846 10

1770-PRO 18.9165174 11

N78S-311 19.2230769 12


Dependent Variable: Moisture

i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 0.2707 0.1760 0.0083 0.0018 0.0005 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001

2 0.2707 0.8092 0.1130 0.0359 0.0134 0.0023 <.0001 <.0001 <.0001 <.0001 <.0001

3 0.1760 0.8092 0.1686 0.0570 0.0221 0.0040 <.0001 <.0001 <.0001 <.0001 <.0001

4 0.0083 0.1130 0.1686 0.5923 0.3528 0.1164 0.0006 0.0006 <.0001 <.0001 <.0001

5 0.0018 0.0359 0.0570 0.5923 0.6930 0.2929 0.0033 0.0032 <.0001 <.0001 <.0001

6 0.0005 0.0134 0.0221 0.3528 0.6930 0.5044 0.0100 0.0093 <.0001 <.0001 <.0001

7 <.0001 0.0023 0.0040 0.1164 0.2929 0.5044 0.0582 0.0501 0.0003 <.0001 <.0001

8 <.0001 <.0001 <.0001 0.0006 0.0033 0.0100 0.0582 0.8707 0.0779 0.0185 0.0005

9 <.0001 <.0001 <.0001 0.0006 0.0032 0.0093 0.0501 0.8707 0.1312 0.0368 0.0015

10 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 0.0003 0.0779 0.1312 0.4823 0.0645

11 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 0.0185 0.0368 0.4823 0.2848

12 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 0.0005 0.0015 0.0645 0.2848

28

Table A.12 Results of Lsmeans procedure for test weight of corn hybrids averaged over all locations

Variety mettest LSMEAN LSMEAN Number

P1319HR 75.7692308 1

P1636YHR 75.1923077 2

DKC65-19 75.1146929 3

DKC62-08 73.7980769 4

DKC66-40 73.4448503 5

1555-SS 73.3653846 6

1133PRO2 73.3613339 7

N70J-401 73.1730769 8

N74G-300 72.5626096 9

1023AM-R 72.4840480 10

1770-PRO 71.9120115 11

N78S-311 69.8076923 12


Dependent Variable: mettest

i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 0.1575 0.1173 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001

2 0.1575 0.8519 0.0008 0.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001

3 0.1173 0.8519 0.0019 0.0003 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001

4 <.0001 0.0008 0.0019 0.4213 0.2882 0.2945 0.1260 0.0035 0.0025 <.0001 <.0001

5 <.0001 0.0001 0.0003 0.4213 0.8563 0.8520 0.5359 0.0495 0.0376 0.0011 <.0001

6 <.0001 <.0001 <.0001 0.2882 0.8563 0.9922 0.6363 0.0553 0.0404 0.0009 <.0001

7 <.0001 <.0001 <.0001 0.2945 0.8520 0.9922 0.6508 0.0620 0.0447 0.0011 <.0001

8 <.0001 <.0001 <.0001 0.1260 0.5359 0.6363 0.6508 0.1438 0.1079 0.0036 <.0001

9 <.0001 <.0001 <.0001 0.0035 0.0495 0.0553 0.0620 0.1438 0.8568 0.1369 <.0001

10 <.0001 <.0001 <.0001 0.0025 0.0376 0.0404 0.0447 0.1079 0.8568 0.2008 <.0001

11 <.0001 <.0001 <.0001 <.0001 0.0011 0.0009 0.0011 0.0036 0.1369 0.2008 <.0001

12 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001

29

Table A.13 Results of Lsmeans procedure for yield of corn hybrids averaged over irrigated locations


DKC62-08 14.7360675 1

P1319HR 14.6341800 2

DKC65-19 14.5432650 3

P1636YHR 14.4931050 4

1133PRO2 14.0714475 5

N74G-300 13.8880500 6

N78S-311 13.8802125 7

DKC66-40 13.6241400 8

1023AM-R 13.5902250 9

1555-SS 13.5040125 10

1770-PRO 12.7986375 11

N70J-401 12.6951825 12



i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 0.8229 0.6722 0.5941 0.1509 0.0696 0.0672 0.0564 0.0163 0.0103 0.0002 <.0001

2 0.8229 0.8417 0.7567 0.2217 0.1083 0.1048 0.0815 0.0275 0.0177 0.0003 0.0002

3 0.6722 0.8417 0.9122 0.3039 0.1566 0.1518 0.1115 0.0429 0.0282 0.0005 0.0003

4 0.5941 0.7567 0.9122 0.3573 0.1897 0.1842 0.1315 0.0542 0.0360 0.0007 0.0004

5 0.1509 0.2217 0.3039 0.3573 0.6872 0.6747 0.4313 0.2945 0.2180 0.0083 0.0047

6 0.0696 0.1083 0.1566 0.1897 0.6872 0.9863 0.6413 0.5141 0.4013 0.0219 0.0128

7 0.0672 0.1048 0.1518 0.1842 0.6747 0.9863 0.6512 0.5252 0.4109 0.0228 0.0133

8 0.0564 0.0815 0.1115 0.1315 0.4313 0.6413 0.6512 0.9522 0.8318 0.1512 0.1078

9 0.0163 0.0275 0.0429 0.0542 0.2945 0.5141 0.5252 0.9522 0.8497 0.0893 0.0562

10 0.0103 0.0177 0.0282 0.0360 0.2180 0.4013 0.4109 0.8318 0.8497 0.1282 0.0828

11 0.0002 0.0003 0.0005 0.0007 0.0083 0.0219 0.0228 0.1512 0.0893 0.1282 0.8202

12 <.0001 0.0002 0.0003 0.0004 0.0047 0.0128 0.0133 0.1078 0.0562 0.0828 0.8202

30

Table A.14 Results of Lsmeans procedure for moisture of corn hybrids averaged over irrigated locations


1023AM-R 15.6500000 1

1133PRO2 16.7000000 2

P1636YHR 16.8000000 3

N70J-401 16.8000000 4

DKC62-08 17.0500000 5

N74G-300 17.1750000 6

P1319HR 17.3750000 7

DKC65-19 17.9000000 8

1555-SS 18.1000000 9

DKC66-40 18.6795455 10

1770-PRO 18.7500000 11

N78S-311 18.7750000 12



i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 0.0472 0.0307 0.0307 0.0097 0.0053 0.0019 0.0001 <.0001 <.0001 <.0001 <.0001

2 0.0472 0.8452 0.8452 0.4960 0.3570 0.1937 0.0246 0.0097 0.0038 0.0003 0.0003

3 0.0307 0.8452 1.0000 0.6261 0.4660 0.2664 0.0382 0.0156 0.0056 0.0006 0.0005

4 0.0307 0.8452 1.0000 0.6261 0.4660 0.2664 0.0382 0.0156 0.0056 0.0006 0.0005

5 0.0097 0.4960 0.6261 0.6261 0.8073 0.5271 0.1044 0.0472 0.0148 0.0022 0.0019

6 0.0053 0.3570 0.4660 0.4660 0.8073 0.6965 0.1636 0.0783 0.0235 0.0041 0.0036

7 0.0019 0.1937 0.2664 0.2664 0.5271 0.6965 0.3094 0.1636 0.0473 0.0110 0.0097

8 0.0001 0.0246 0.0382 0.0382 0.1044 0.1636 0.3094 0.6965 0.2264 0.1044 0.0950

9 <.0001 0.0097 0.0156 0.0156 0.0472 0.0783 0.1636 0.6965 0.3659 0.2102 0.1937

10 <.0001 0.0038 0.0056 0.0056 0.0148 0.0235 0.0473 0.2264 0.3659 0.9119 0.8808

11 <.0001 0.0003 0.0006 0.0006 0.0022 0.0041 0.0110 0.1044 0.2102 0.9119 0.9611

12 <.0001 0.0003 0.0005 0.0005 0.0019 0.0036 0.0097 0.0950 0.1937 0.8808 0.9611

31

Table A.14 Results of Lsmeans procedure for test weight of corn hybrids averaged over irrigated locations


P1319HR 75.6250000 1

DKC65-19 75.6250000 2

P1636YHR 75.0000000 3

1555-SS 74.6875000 4

DKC62-08 74.0625000 5

DKC66-40 73.4659091 6

N70J-401 73.4375000 7

1133PRO2 73.1250000 8

1770-PRO 72.8125000 9

1023AM-R 72.5000000 10

N74G-300 72.1875000 11

N78S-311 70.3125000 12



i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 1.0000 0.4261 0.2356 0.0525 0.0323 0.0082 0.0030 0.0010 0.0003 0.0001 <.0001

2 1.0000 0.4261 0.2356 0.0525 0.0323 0.0082 0.0030 0.0010 0.0003 0.0001 <.0001

3 0.4261 0.4261 0.6896 0.2356 0.1215 0.0525 0.0216 0.0082 0.0030 0.0010 <.0001

4 0.2356 0.2356 0.6896 0.4261 0.2143 0.1169 0.0525 0.0216 0.0082 0.0030 <.0001

5 0.0525 0.0525 0.2356 0.4261 0.5403 0.4261 0.2356 0.1169 0.0525 0.0216 <.0001

6 0.0323 0.0323 0.1215 0.2143 0.5403 0.9767 0.7259 0.5027 0.3238 0.1942 0.0026

7 0.0082 0.0082 0.0525 0.1169 0.4261 0.9767 0.6896 0.4261 0.2356 0.1169 0.0003

8 0.0030 0.0030 0.0216 0.0525 0.2356 0.7259 0.6896 0.6896 0.4261 0.2356 0.0010

9 0.0010 0.0010 0.0082 0.0216 0.1169 0.5027 0.4261 0.6896 0.6896 0.4261 0.0030

10 0.0003 0.0003 0.0030 0.0082 0.0525 0.3238 0.2356 0.4261 0.6896 0.6896 0.0082

11 0.0001 0.0001 0.0010 0.0030 0.0216 0.1942 0.1169 0.2356 0.4261 0.6896 0.0216

12 <.0001 <.0001 <.0001 <.0001 <.0001 0.0026 0.0003 0.0010 0.0030 0.0082 0.0216

32

Table A.16 Results of Lsmeans procedure for yield of corn hybrids averaged over non irrigated locations


DKC62-08 13.0527467 1

1133PRO2 12.6619352 2

DKC65-19 12.4887384 3

P1319HR 12.3588667 4

DKC66-40 12.2739909 5

N78S-311 12.2056000 6

1555-SS 11.8335800 7

P1636YHR 11.8238267 8

1023AM-R 11.7137211 9

N74G-300 11.5545084 10

N70J-401 11.4838533 11

1770-PRO 11.2907864 12



i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 0.3479 0.1770 0.0869 0.0636 0.0375 0.0031 0.0029 0.0026 0.0005 0.0002 0.0001

2 0.3479 0.6865 0.4662 0.3669 0.2736 0.0488 0.0462 0.0345 0.0114 0.0056 0.0028

3 0.1770 0.6865 0.7546 0.6145 0.4961 0.1175 0.1122 0.0848 0.0307 0.0175 0.0085

4 0.0869 0.4662 0.7546 0.8381 0.7029 0.1933 0.1852 0.1380 0.0556 0.0318 0.0152

5 0.0636 0.3669 0.6145 0.8381 0.8692 0.2907 0.2802 0.2108 0.0941 0.0599 0.0296

6 0.0375 0.2736 0.4961 0.7029 0.8692 0.3556 0.3432 0.2567 0.1198 0.0752 0.0367

7 0.0031 0.0488 0.1175 0.1933 0.2907 0.3556 0.9806 0.7815 0.5023 0.3850 0.2110

8 0.0029 0.0462 0.1122 0.1852 0.2802 0.3432 0.9806 0.7988 0.5173 0.3983 0.2193

9 0.0026 0.0345 0.0848 0.1380 0.2108 0.2567 0.7815 0.7988 0.7209 0.5949 0.3608

10 0.0005 0.0114 0.0307 0.0556 0.0941 0.1198 0.5023 0.5173 0.7209 0.8649 0.5542

11 0.0002 0.0056 0.0175 0.0318 0.0599 0.0752 0.3850 0.3983 0.5949 0.8649 0.6550

12 0.0001 0.0028 0.0085 0.0152 0.0296 0.0367 0.2110 0.2193 0.3608 0.5542 0.6550

33

Table A.17 Results of Lsmeans procedure for moisture of corn hybrids averaged over non irrigated locations


1133PRO2 16.8204505 1

P1636YHR 16.8888889 2

1023AM-R 16.9040766 3

N70J-401 17.4333333 4

DKC62-08 17.5333333 5

P1319HR 17.5444444 6

N74G-300 17.9110311 7

DKC66-40 18.2360311 8

DKC65-19 18.3610311 9

1770-PRO 18.9701247 10

1555-SS 18.9888889 11

N78S-311 19.4222222 12



i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 0.8339 0.8099 0.0629 0.0311 0.0286 0.0003 <.0001 <.0001 <.0001 <.0001 <.0001

2 0.8339 0.9643 0.0872 0.0436 0.0402 0.0004 <.0001 <.0001 <.0001 <.0001 <.0001

3 0.8099 0.9643 0.1214 0.0663 0.0617 0.0015 0.0003 <.0001 <.0001 <.0001 <.0001

4 0.0629 0.0872 0.1214 0.7515 0.7250 0.0910 0.0156 0.0055 <.0001 <.0001 <.0001

5 0.0311 0.0436 0.0663 0.7515 0.9719 0.1801 0.0336 0.0128 <.0001 <.0001 <.0001

6 0.0286 0.0402 0.0617 0.7250 0.9719 0.1931 0.0365 0.0140 <.0001 <.0001 <.0001

7 0.0003 0.0004 0.0015 0.0910 0.1801 0.1931 0.2641 0.1233 0.0008 0.0002 <.0001

8 <.0001 <.0001 0.0003 0.0156 0.0336 0.0365 0.2641 0.7090 0.0383 0.0231 0.0005

9 <.0001 <.0001 <.0001 0.0055 0.0128 0.0140 0.1233 0.7090 0.0844 0.0570 0.0016

10 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 0.0008 0.0383 0.0844 0.9559 0.1849

11 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 0.0002 0.0231 0.0570 0.9559 0.1722

12 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 0.0005 0.0016 0.1849 0.1722

34

Table A.18 Results of Lsmeans procedure for test weight of corn hybrids averaged over non irrigated locations


P1319HR 75.8333333 1

P1636YHR 75.2777778 2

DKC65-19 74.8765497 3

DKC62-08 73.6805556 4

1133PRO2 73.4979635 5

DKC66-40 73.3921747 6

N70J-401 73.0555556 7

1555-SS 72.7777778 8

N74G-300 72.7671747 9

1023AM-R 72.5134404 10

1770-PRO 71.4186848 11

N78S-311 69.5833333 12



i/j 1 2 3 4 5 6 7 8 9 10 11 12

1 0.2327 0.0486 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001

2 0.2327 0.4036 0.0009 0.0004 0.0002 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001

3 0.0486 0.4036 0.0143 0.0065 0.0033 0.0003 <.0001 <.0001 <.0001 <.0001 <.0001

4 <.0001 0.0009 0.0143 0.7033 0.5479 0.1799 0.0542 0.0595 0.0213 <.0001 <.0001

5 <.0001 0.0004 0.0065 0.7033 0.8308 0.3571 0.1356 0.1425 0.0565 0.0001 <.0001

6 <.0001 0.0002 0.0033 0.5479 0.8308 0.4832 0.2022 0.2059 0.0903 0.0002 <.0001

7 <.0001 <.0001 0.0003 0.1799 0.3571 0.4832 0.5494 0.5479 0.2786 0.0015 <.0001

8 <.0001 <.0001 <.0001 0.0542 0.1356 0.2022 0.5494 0.9824 0.5962 0.0077 <.0001

9 <.0001 <.0001 <.0001 0.0595 0.1425 0.2059 0.5479 0.9824 0.6219 0.0102 <.0001

10 <.0001 <.0001 <.0001 0.0213 0.0565 0.0903 0.2786 0.5962 0.6219 0.0425 <.0001

11 <.0001 <.0001 <.0001 <.0001 0.0001 0.0002 0.0015 0.0077 0.0102 0.0425 0.0004

12 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 0.0004