corn grain yield components and nutrient accumulation in response to nitrogen, plant density and

145 Pages·2017·0.79 MB·English

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Theses and Dissertations--Plant and Soil
Plant and Soil Sciences
Sciences
2018
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Maria Julia Santoro
University of Kentucky, [email protected]
Digital Object Identifier: https://doi.org/10.13023/ETD.2018.064
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Santoro, Maria Julia, "CORN GRAIN YIELD COMPONENTS AND NUTRIENT ACCUMULATION IN RESPONSE
TO NITROGEN, PLANT DENSITY AND HYBRID" (2018). Theses and Dissertations--Plant and Soil Sciences.
100.
https://uknowledge.uky.edu/pss_etds/100
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Maria Julia Santoro, Student
Dr. Chad D. Lee, Major Professor
Dr. Mark Coyne, Director of Graduate Studies
CORN GRAIN YIELD COMPONENTS AND NUTRIENT ACCUMULATION IN
RESPONSE TO NITROGEN, PLANT DENSITY AND HYBRID

THESIS

A thesis submitted in partial fulfillment of the
requirements for the degree of Master of Science in the
College of Agriculture, Food and Environment
at the University of Kentucky

by

Maria Julia Santoro

Lexington, Kentucky

Director: Dr. Chad D. Lee, Professor of Agronomy

Lexington, Kentucky

2018

Copyright © Maria Julia Santoro 2018
ABSTRACT OF THESIS

CORN GRAIN YIELD COMPONENTS AND NUTRIENT ACCUMULATION IN
RESPONSE TO NITROGEN, PLANT DENSITY AND HYBRID

Modern maize hybrids exhibit higher yields, increased biomass production, stress
tolerance and greater nitrogen (N) use efficiency. Increased biomass accumulation can
influence nutrient uptake and lead to increased nutrient removal. Hybrids were tested at
seeding rates (SR) of 74000 (low) and 148000 (supraoptimal) plants ha-1 and at N rates of
0 (deficient) and 390 (non-limiting) kg N ha-1. Plants were sampled at V7, V14, R3, R5
and R6 and separated into vegetative and reproductive fractions for determination of dry
matter and N accumulation. Grain yield was harvested at R6.
The high SR and high N treatment combination resulted in greatest biomass accumulation,
crop growth rates, and N accumulation per hectare in both vegetative and grain tissues.
The high SR and high N combination maximized grain yield at 20.6 Mg ha-1, essentially
through an increase in kernels ha-1. High SR decreased kernel weight, even with high N.
At the higher plant densities resulting from the high SR, however, average utilization of
available N was enhanced. The results have implications for improved management
practices under high input systems and providing insight to growers who incorporate
variable seed and N rates.

KEYWORDS: nitrogen rates, plant density, maize, nutrient uptake, grain yield, yield
components.

Maria Julia Santoro
February 23, 2018
CORN GRAIN YIELD COMPONENTS AND NUTRIENT ACCUMULATION IN
RESPONSE TO NITROGEN, PLANT DENSITY AND HYBRID

by
Maria Julia Santoro

Dr. Chad D. Lee
Director of Thesis

Dr. Mark Coyne
Director of Graduate Studies

February 23, 2018
TABLE OF CONTENTS
List of Tables…………………………………………………………………………..... vi
List of Figures………………………………………………………………………….... ix

Chapter 1: Literature Review………………………………………………………….......1

1. Introduction…………………………………………………………………………....1
1.1. Which key factors contributed to higher maize grain yields?..............................2
1.1.1. Higher Populations and Narrow Rows…………………………………....2
1.1.2. Nitrogen Fertilizer Use…………………………………………………....6
1.1.3. Improved Nitrogen Use Efficiency in Modern Maize Hybrids……….......9
1.2. Yield Components……………………………………………………………....10
1.2.1. Kernel Number…………………………………………………………. 12
1.2.2. Kernel Weight………………………………………………………...... 15
1.3. Nutrient Uptake and Accumulation……………………………………………. 16
1.3.1. Nitrogen………………………………………………………………… 17
1.3.2. Phosphorus and Potassium………………………………………………19

Chapter 2:

2. Materials and Methods……………………………………………………………….21
2.1. Study Design and Treatments…………………………………………………...21
2.2. Planting………………………………………………………………………….22
2.3. Nitrogen Application……………………………………………………………22
2.4. Management…………………………………………………………………… 23
2.5. Climate……………………………………………………………………….... 24
2.6. Soil Sampling for Nitrogen……………………………………………………. 25
2.7. Combine Harvest………………………………………………………………. 26
2.8. Plot Ear Harvest………………………………………………………………. 26
2.9. Post – Harvest Measurements…………………………………………………. 26
2.9.1. Kernel Number and Kernel Mass………………………………………. 26
2.9.2. Ear Length and Tip-Back Length………………………………………. 27
2.9.3. Harvest Index…………………………………………………………… 27
2.10. Aboveground Plant Biomass and Nutrient Uptake………………………27
2.11. Nutrient Analysis………………………………………………………. 28
2.12. Nitrogen Deficiency Rating……………………………………………. 29
2.13. Nitrogen Indices…………………………………………………………29
2.13.1. Nitrogen Harvest Index (NHI)…………………………………………...29
2.13.2. Nitrogen Internal Efficiency (NIE)….…………….……………………. 30
2.14. Statistical Data Analyses………………………………………………... 30
2.14.1. Grain Yield and Yield Components……………………………………...30
2.14.2. Nutrient Uptake…………………………………………………………. 31
2.14.3. Crop Growth Rate (CGR)………………………………………………. 32

Chapter 3:
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3. Grain Yield and Yield Components…………………………………………………33
3.1. Objectives……………………………………………………………………….33
3.2. Results………………………………………………………………………….33
3.2.1. Weather Conditions……………………………………………………...33
3.2.2. Grain Yield………………………………………………………………34
3.2.3. Grain Yield Components………………………………………………...35
3.2.3.1. Kernel Number…………………………………………………. 35
3.2.3.2. Kernel Weight……………………………………………………38
3.2.4. Biomass…………………………………………………………………. 38
3.2.5. Grain Harvest Index……………………………………………………...40
3.2.6. Stalk Weakness…………………………………………………………. 41
3.3. Discussion……………………………………………………………………….60
3.3.1. Grain Yield Responsiveness……………………………………………. 60
3.3.2. Grain Yield Components………………………………………………...62
3.3.3. Biomass…………………………………………………………………. 67
3.3.4. Grain Harvest Index……………………………………………………...69
3.3.5. Stalk Weakness…………………………………………………………. 70
3.4. Summary………………………………………………………………………...71

Chapter 4:

4. Nutrient Uptake and Accumulation………………………………………………….72
4.1. Objectives……………………………………………………………………….72
4.2. Results…………………………………………………………………………. 72
4.2.1. Stem & Leaf Nitrogen Accumulation…………………………………...72
4.2.2. Husk and Cob Nitrogen Uptake………………………………………...74
4.2.3. Cob + Grain N Uptake at R3…………………………………………....75
4.2.4. Grain Nutrient Removal………………………………………….…......76
4.2.5. Whole Plant N Uptake…………………………………………………. 78
4.2.6. Nitrogen Deficiency Rating……………………………………………. 79
4.3. Discussion……………………………………………………………………...106
4.3.1. Soil Nitrogen …………………………………………………………...106
4.3.2. Stem and Leaf N Accumulation throughout the growing season……... 106
4.3.3. Husk and Cob N Uptake evolution……………………………………. 109
4.3.4. Whole Plant N Accumulation…………………………………………. 110
4.3.5. Grain N Removal at Harvest……………………………………………111
4.3.6. Grain P and K Removal Relationship with Grain N Removal……........115
4.3.7. Nitrogen Deficiency observed at Reproductive Growth Stages………..116
4.4. Summary……………………………………………………………………….117

Chapter 5:

5. Conclusions………………………………………………………………………....118

Appendix………………………………………………………………………………. 121
iv
References………………………………………………………………………………125

VITA……………………………………………………………………………………133

v
List of Tables

Table 3.1: N rate, seeding rate, hybrid, soil type, soil taxonomy classification and soil
properties within each environment. ………………………………………….. ……….42

Table 3.2: ANOVA table summarizing sources of variation per environment. ………...43

Table 3.3: Seeding rate effect on Grain Yield, Kernels per hectare and 1000 Kernel
Weight within Environment, Hybrid and N Rate. …………...………………………….44

Table 3.4: Predicted ear length response to actual plant population density for each
hybrid. …………………………………………………………………………………...45

Table 3.5: Predicted tip-back response to actual plant population density for each hybrid
in Lexington and Hardin 2016. ………………………………………………………….46

Table 3.6: ANOVA table for stem and leaf biomass summarizing sources of variation...47

Table 3.7: ANOVA table for grain biomass summarizing sources of variation. ………. 48

Table 3.8: ANOVA table for cob biomass summarizing sources of variation. …………49

Table 3.9: ANOVA table for husk biomass summarizing sources of variation. ………. 49

Table 3.10: ANOVA table for grain harvest index summarizing sources of variation… 50

Table 3.11: Growth stage effect on Stem & Leaf Dry Matter per hectare within N Rate for
Lexington 2015. …………………………………………………………………………51

Table 3.12: Seeding rate and Growth Stage effects on Stem & Leaf Dry Matter per hectare
within Hybrid for Lexington 2015. ………………………………………………………51

Table 3.13: N rate, seeding rate and Growth Stage effects on Stem & Leaf Dry Matter per
hectare for Lexington 2016.………………………………………………………………52

Table 3.14: Hybrid and Growth Stage effects on Stem & Leaf Dry Matter per hectare
within N rate for Lexington 2016. ……………………………………………………... 53

Table 3.15: N and seeding rate effects on Grain Dry Matter per hectare across two hybrids
and three environments.………………………………………………………………… 54

Table 3.16: N and seeding rate effects on Grain Dry Matter per hectare for LEX2016 and
HAR2016.……………………………………………………………………………… 54

Table 3.17: N and seeding rate effects on Cob Dry Matter per hectare across hybrids for
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Lexington and Hardin 2016. …………………………………………………………… 54

Table 3.18: N rate and Hybrid effects on Husk Dry Matter per hectare across seed rates
for Lexington 2016. …………………………………………………………………… 55

Table 4.1: Soil nitrogen concentrations (ppm) for each Environment expressed as
NH +-N (Ammonium-N), NO —N (Nitrate-N) and inorganic Total N.…………………81
4 3

Table 4.2: ANOVA table for Stem and Leaf N uptake. …………………….…………. 82

Table 4.3: ANOVA table for Husk N uptake at R5 for Lex 2015 and at R3, R5 and R6 at
Lex 2016. ………………………………………………………………………………. 83

Table 4.4: ANOVA table for Cob N uptake at R5 for Lex 2015 and at R5 and R6 for Lex
2016. …………………………………………………………………………………….84

Table 4.5: ANOVA table for Cob + Grain N uptake at R3. ………………………….....85

Table 4.6: ANOVA table for Grain N uptake at maturity. ………………..…………….86

Table 4.7: ANOVA table for Grain N uptake per plant at maturity. ……………..……. 87

Table 4.8: ANOVA table for Whole Plant N uptake. …………………………..……… 88
.
Table 4.9. ANOVA table for nitrogen harvest index (NHI)……………………..……....89

Table 4.10. ANOVA table for crop growth rate (CGR)………………………..………. 90

Table 4.11. ANOVA table for N deficiency rating……………………………...………91

Table 4.12. ANOVA table for nitrogen internal efficiency (NIE) for LEX2015 and
LEX2016………………………………………………………………………..……….92

Table 4.13: Seeding rate and Growth Stage effects on Stem and Leaf N uptake per
hectare within N rate for LEX2015. ……………………………………………….……93

Table 4.14: Seeding rate and Growth Stage effects on Stem & Leaf N uptake per hectare
within N Rate for LEX2016. …………………………………………………….……. 94

Table 4.15: Seeding rate and Hybrid effects on R5 Husk and Cob N uptake per hectare
within N Rate. ………………………………………………………………………….. 95

Table 4.16: Seeding rate effect on Husk and Cob N uptake per hectare within Growth
Stage. ……………………………………………………………………………………96

vii