combining ability, heterosis, and genetic diversity in tropical maize inbreds and synthetics under

221 Pages·2005·1.89 MB·English

by  Dan Makumbi

PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF
WHITE MAIZE INBREDS, HYBRIDS AND SYNTHETICS UNDER STRESS
AND NON-STRESS ENVIRONMENTS

A Dissertation
by
DAN MAKUMBI

Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of

DOCTOR OF PHILOSOPHY

August 2005

Major Subject: Plant Breeding
PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF
WHITE MAIZE INBREDS, HYBRIDS AND SYNTHETICS UNDER STRESS
AND NON-STRESS ENVIRONMENTS

A Dissertation
by
DAN MAKUMBI

Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of

DOCTOR OF PHILOSOPHY

Approved by:

Chair of Committee, Javier F. Betrán
Committee Members, William L. Rooney
J. Tom Cothren
Tim H. Murphy
Head of Department, C. Wayne Smith

August 2005

Major Subject: Plant Breeding
iii
ABSTRACT

Phenotypic and Genotypic Characterization of White Maize Inbreds, Hybrids and Synthetics
under Stress and Non-Stress Environments.
(August 2005)
Dan Makumbi, B.Sc., Makerere University, Kampala, Uganda;
M.Sc., Makerere University, Kampala, Uganda
Chair of Advisory Committee: Dr. Javier F. Betrán

Maize is susceptible to biotic and abiotic stresses. The most important abiotic stresses in
Africa are drought and low soil fertility. Aflatoxin contamination is a potential problem in areas
facing drought and low soil fertility. Three studies were conducted to evaluate maize germplasm
for tolerance to stress. In the first study, fifteen maize inbred lines crossed in a diallel were
evaluated under drought, low N stress, and well-watered conditions at six locations in three
countries to estimate general (GCA) and specific combining ability (SCA), investigate genotype
x environment interaction, and estimate genetic diversity and its relationship with grain yield and
heterosis. GCA effects were not significant for grain yield across environments. Lines with good
GCA effect for grain yield were P501 and CML258 across stresses. Lines CML339, CML341,
and SPLC7-F had good GCA effects for anthesis silking interval across stresses. Additive
genetic effects were more important for grain yield under drought and well-watered conditions.
Heterosis estimates were highest in stress environments. Clustering based on genetic distance
calculated using marker data from AFLP, RFLP, and SSRs grouped lines according to origin.
Genetic distance was positively correlated with grain yield and specific combining ability. In the
second study, synthetic hybrids were evaluated at seven locations in three countries to estimate
GCA and SCA effects under low N stress and optimal conditions and investigate genotype x
environment interaction. GCA effects were significant for all traits across low N stress and
optimal conditions. The highest yielding synthetic hybrids involved synthetics developed from
stress tolerant lines. Synthetics 99SADVIA-# and SYNA00F2 had good GCA for grain yield
across low N stress conditions. Heterosis was highly correlated with grain yield. Optimal
environments explained more variation than stress environments. The third study evaluated the
agronomic performance and aflatoxin accumulation of single and three-way cross white maize
hybrids at five locations in Texas. Inbreds CML343, Tx601W, and Tx110 showed positive GCA
iv
effects for grain yield. Significant GCA effects for reduced aflatoxin concentration were
observed in lines CML269, CML270, and CML78 across locations. Differences in performance
between single and three-way crosses hybrids were dependent mostly on the inbred lines.
v

DEDICATION

This dissertation is dedicated to the memories of my father Kosai, brothers Robert and
Kefa, and sisters Margaret and Beatrice who did not live to see me get this far. Your support was
always great.
vi

ACKNOWLEDGEMENTS

I would like to thank most sincerely Dr. Javier F. Betrán, my major professor and chair
of my graduate committee for his guidance and support not only in accomplishing this research
work and doctoral level studies here at Texas A&M University but also in other aspects
throughout the entire stay here in the United States. I greatly appreciate all the help he availed to
me while pursuing my studies. I would also like to thank the members of my graduate
committee, Dr. William L. Rooney, Dr. Tom Cothren, and Dr. Tim Murphy for their guidance
and constructive comments during the course of my studies.
I would also like to extend my sincere thanks to the Rockefeller Foundation, through Dr.
John O’Toole and Dr. Joe DeVries for the financial support that enabled me to study at Texas
A&M University. Special thanks go to Dr. Marianne Bänziger and Dr. Kevin Pixley of
CIMMYT for their tremendous support, guidance, encouragement, and input throughout this
period. The assistance provided by Dr. Jean-Marcel Ribaut of CIMMYT with molecular marker
work is highly appreciated. The help provided by the Head, Cereals Program at NARO, Dr.
George Bigirwa is greatly appreciated. At the same time I would like to thank all the technical
staff at all the locations for their dedication to duty which enabled me to collect good data. The
help of Nathan Damu and Sebastian Mawere at CIMMYT-Zimbabwe; Annet Nakayima, Majid
Walusimbi, Paddy Kibuuka, and Michael Abigaba at Namulonge Research Station in Uganda;
and Moses and Anne at Alupe in Kenya is greatly acknowledged. To all, I say thank you so
much.
I would like to express my appreciation to my colleagues and fellow students at the Corn
Breeding and Genetics laboratory – Francis, Cosmos, Rosan, Kerry, Halima, Brett, Cody,
Sandeep and Dennis for their support, companionship and encouragement.
I would also like to acknowledge the love and understanding of my family during my
studies and stay in Texas. My wife Rose and children Doreen, Beatrice, Brittany, Alvin and
Kelvin - thank you for your patience. The help provided by Lydia was great.
In closing, I thank God. For only through God’s grace and blessings has this pursuit
been possible.
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TABLE OF CONTENTS

Page

ABSTRACT………………………………………………………………………………. iii

DEDICATION………………………………………………………………..................... v

ACKNOWLEDGEMENTS……………………………………………………................. vi

TABLE OF CONTENTS………………………………………………………................. vii

LIST OF TABLES………………………………………………………………............... ix

LIST OF FIGURES…………………………………………………………..................... xiv

CHAPTER

I INTRODUCTION………………………...…………….……....................... 1

II COMBINING ABILITY, HETEROSIS, AND GENETIC DIVERSITY IN
TROPICAL MAIZE INBREDS UNDER STRESS AND NON-STRESS
CONDITIONS…...……………….................................................................. 5

Introduction…………………………………….…………................. 5
Review of Literature……………………………..………………….. 7
Materials and Methods……………………………...…..…………... 18
Results and Discussion……………………………...…..…………... 24
Conclusions………………………………………………………….. 82

III PERFORMANCE OF SYNTHETIC MAIZE HYBRIDS UNDER LOW
NITROGEN STRESS AND OPTIMAL CONDITIONS……………............ 83

Introduction………………………………………..………………… 83
Review of Literature……………………...………..………………... 85
Materials and Methods…………………………….………………... 91
Results and Discussion…………………………….………………... 98
Conclusions……………………………………………….................. 132

IV AGRONOMIC PERFORMANCE AND AFLATOXIN ACCUMULATION
IN SINGLE AND THREE-WAY CROSS WHITE MAIZE HYBRIDS…… 133

Introduction………………………………………..…..….................. 133
Review of Literature………………………...……..………………... 135
Materials and Methods……………………………..……………….. 140
Results and Discussion………………………….....………………... 144
Conclusions……………………………………………….................. 171
viii
CHAPTER Page

V SUMMARY AND CONCLUSIONS ……………………..………………... 172

Study 1: Combining ability, heterosis, and genetic diversity in
tropical maize inbreds under stress and non-stress conditions…...…. 172
Study 2: Performance of synthetic maize hybrids under low nitrogen
stress and optimal conditions…..…..…..…..…..…..………………... 173
Study 3: Agronomic performance and aflatoxin accumulation in
single and three-way cross white maize hybrids..…………………... 174

REFERENCES………………………………………………………...………....………. 175

APPENDIX A………………………………………………………….………...………. 189

APPENDIX B………………………………………………………….………....………. 192

APPENDIX C………………………………………………………….………....………. 195

APPENDIX D………………………………………………………….………...………. 196

APPENDIX E………………………………………………………….………....………. 197

APPENDIX F………………………………………………………….………....………. 200

APPENDIX G……………………………………………………….……….......………. 202

APPENDIX H………………………………………………………….………...………. 204

VITA……………………………………………………………….......………...………. 205
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LIST OF TABLES

TABLE Page

2.1 Maize inbred lines used in the diallel study evaluated under stress and non-stress
conditions in Africa and America, their pedigree, and classification..………………. 18

2.2 Locations and environments used to evaluate F1 hybrids and inbred lines and their
characteristics and codes……………………………………….................................. 21

2.3 Combined analysis of variance and means for grain yield and agronomic traits
across well-watered environments…………………………………………………… 25

2.4 Combined analysis of variance and means for grain yield and agronomic traits
across low N stress environments …………………………………………………… 27

2.5 Combined analysis of variance and means for grain yield and agronomic traits
across drought stress environments …………………………………………………. 28

2.6 Combined analysis of variance and means for grain yield and agronomic traits
across environments ………………………………………………………………… 30

2.7 General combining ability effects (GCA) of fifteen maize inbred lines for anthesis
silking interval per environment and across environments………………………….. 32

2.8 General combining ability effects (GCA) of fifteen maize inbred lines for ears per
plant per environment and across environments…………………………………….. 33

2.9 General combining ability effects (GCA) of fifteen maize inbred lines for grain
yield (Mg ha-1) per environment and across environments………………….………. 36

2.10 General combining ability effects (GCA) of fifteen maize inbred lines for anthesis
date per environment and across environments….…………………………………... 37

2.11 General combining ability effects (GCA) of fifteen maize inbred lines for silking
date per environment and across environments…..………………………………….. 38

2.12 General combining ability effects (GCA) of fifteen maize inbred lines for plant
height per environment and across environments…...……………………………….. 40

2.13 General combining ability effects (GCA) of fifteen maize inbred lines for ear height
per environment and across environments……..……………………………………. 41

2.14 General combining ability effects (GCA) of fifteen maize inbred lines for grain
moisture per environment and across environments...………………………………. 42
x

TABLE Page

2.15 General combining ability effects (GCA) of fifteen maize inbred lines for leaf
senescence at two environments and across environments…..……………………… 43

2.16 Ratio of additive genetic variance to total genetic variance for grain yield and
agronomic traits at each environment and across environments…..………………… 47

2.17 Genetic correlations (upper diagonal) and phenotypic correlations (below diagonal)
between grain yield and agronomic traits across well-watered environments…….… 50

2.18 Genetic correlations (upper diagonal) and phenotypic correlations (below diagonal)
between grain yield and agronomic traits across drought stress environments……… 50

2.19 Genetic correlations (upper diagonal) and phenotypic correlations (below diagonal)
between grain yield and agronomic traits across environments…............................... 51

2.20 Repeatability on mean basis (± standard error) for grain yield and agronomic traits
at each environment…………………………………………………………………. 54

2.21 Variance component estimates for grain yield of 15 maize inbred lines at 8
environments………………………………………………………………………… 55

2.22 Repeatability on mean basis for grain yield and agronomic traits across
environments………………………………………………...………………………. 55

2.23 Variance component estimates for agronomic traits of 15 maize inbred lines across
low N stress, drought stress, and well-watered environments……………………….. 57

2.24 Combined analysis of variance and means for grain yield and agronomic traits
across environments for inbred lines………………………………………………… 58

2.25 Genetic correlations (upper diagonal) and phenotypic correlations (below diagonal)
between grain yield and agronomic traits across environments for inbred
lines……………………………………….………………………………………….. 59

2.26 Repeatability on mean basis (± standard error) for 15 maize inbred lines at 4
environments and across environments…………………..………………………….. 60

2.27 Mean grain yield and anthesis silking interval of inbred lines in hybrid combination
and grain yield of inbred lines per se and their phenotypic stability
(b)………………..…………………………………………………………………… 68

2.28 Analysis of variance for the Additive Main Effect and Multiplicative Interaction
(AMMI) model……………………………………………………..………………... 70