HETEROTIC GROUPING OF SELECTED INBRED LINES OF MAIZE (Zea mays L.) USING TWO TESTERS IN KIAMBU AND EMBU COUNTIES, KENYA BY CHEMELI JANE (BSC. AGED) REG. NO. 156/CE/22771/2010 A thesis submitted in partial fulfillment of the requirements for the award of the degree of Master of Science (Genetics) in the School of Pure and Applied Sciences of Kenyatta University. FEBRUARY 2016 ii DECLARATION This thesis is my original work and has not been presented for a degree or any other award in any other university. Chemeli Jane Signature---------------------------------------Date ------------------------------- This thesis has been submitted for examination with our approval as the university supervisors. Dr. Fredrick Njoka Dean, School of Agriculture Embu University College Signature-----------------------------------------Date ----------------------------------- Dr. Philip Leley Maize Breeder KALRO Muguga South Nairobi, Kenya Signature-----------------------------------------Date ----------------------------------- iii DEDICATION To my progenies; Amon, Allan, Alvin, Austin and Adalia. Also to my husband for his love and encouragement. iv ACKNOWLEDGEMENT I am highly indebted to my supervisors, Dr. F. Njoka and Dr. P. K. Leley who I profoundly thank for their exemplary intellectual guidance and support during the entire degree course. This work could not have been accomplished without their concern, patience, understanding, moral and material support. Much thanks go to Prof. Dauglas Ndiritu for the genetic courses he taught me prior to this project. Special thanks go to Dr. F. Njoka for his useful and critical deliberations on the research proposal, progress reports and research findings. Dr. P. K Leley provided the germplasm that were used in the research, to him am indebted. Dr. Kipchumba Chelimo of Georgia University and Dr. Elias Thuranira of NARES were a constant source of knowledge and skills in breeding experiments. I am grateful to my course mate Jennifer Kariuki for the ideas shared and lessons learned. Her company and warmth in the course of the research made the going worthwhile. I would also like to appreciate the assistance from KALRO stations in Muguga and Embu for providing the field where this study was carried out. Furthermore I cannot thank enough, the KALRO staff; Peter Njoroge the senior technician at KALRO Muguga for his advice on randomization of the inbred lines, Ann Ndambuki and Florence Gatumu for taking good care of the trials, John Gaitho for providing transport logistics to the study areas. The constant encouragement from Stephen Gichobi the senior technician in the department of Plant Sciences of Kenyatta University cannot go unnoticed. To all the support staff of plant sciences and all those who were a constant source of knowledge and skills, I will always be grateful. v TABLE OF CONTENTS TITLE...……………………………………………………………………………………………i DECLARATION ....................................................................................................................... ii DEDICATION .......................................................................................................................... iii ACKNOWLEDGEMENT ..........................................................................................................iv TABLE OF CONTENT .............................................................................................................. v LIST OF FIGURES ................................................................................................................ viii LIST OF TABLES .....................................................................................................................ix LIST OF PLATES .....................................................................................................................xi LIST OF APPENDICES……………………………………..……………………………….…xii DEFINITION OF TERMS……………………………………………………………………...xii ACRONYMS AND ABBREVIATIONS .................................................................................. xv ABSTRACT ...........................................................................................................................xvii CHAPTER ONE ......................................................................................................................... 1 INTRODUCTION ...................................................................................................................... 1 1.2 Global production of maize ................................................................................................3 1.3 Maize production constraints .............................................................................................4 1.4 problem Statement .............................................................................................................5 1.5 Justification of the study ....................................................................................................6 1.6 Null hypotheses .................................................................................................................6 1.7 General objective ...............................................................................................................7 1.7.1 Specific objectives .......................................................................................................7 CHAPTER TWO ........................................................................................................................ 8 LITERATURE REVIEW ............................................................................................................ 8 2.1 Biology of maize ...............................................................................................................8 2.2 Maize breeding in Kenya ................................................................................................. 10 vi 2.3 Heterotic Groups.............................................................................................................. 16 2.4 Combining Ability ........................................................................................................... 18 2.5 Testers in breeding programs ........................................................................................... 19 CHAPTER THREE................................................................................................................... 21 MATERIALS AND METHODS............................................................................................... 21 3.1 Study area and materials .................................................................................................. 21 3.1.1 Study area ................................................................................................................. 21 3.1.2 Study materials .......................................................................................................... 24 3.2 Experimental layout ......................................................................................................... 25 3.3 Planting and field management ........................................................................................ 27 3.4 Data collected .................................................................................................................. 28 3.4.1 Plant height ............................................................................................................... 28 3.4.2 Ear height .................................................................................................................. 29 3.4.3 Moisture Content ....................................................................................................... 29 3.4.4 Disease scores ........................................................................................................... 29 3.4.5 Grain yield ................................................................................................................ 30 3.5 Data analysis.................................................................................................................... 30 CHAPTER FOUR ..................................................................................................................... 32 RESULTS AND DISCUSSION ................................................................................................ 32 4.1 Single site analysis ........................................................................................................... 32 4.1.1 Embu County………………………………………………………………………….32 4.1.1.1 Agronomic traits of the crosses between inbred lines and two testers in Embu County ............................................................................................................. 32 4.1.1.2 Correlation between agronomic traits of crosses in Embu .................................... 33 4.1.2 Muguga, Kiambu County……………………………………………………………..34 4.1.2.1: Agronomic traits of the crosses between inbred lines and two testers in Muguga, Kiambu county ............................................................................................ 34 4.1.2.2: Correlation between agronomic traits in Muguga ............................................... 37 4.2 Multiple site analysis in Embu and Muguga………………………………………………37 4.2.1 Agronomic traits of crosses between inbred lines and two testers in Embu and Muguga ....................................................................................................................... 37 4.2.2 Mean values of all the agronomic traits measured