Morphological Characterization and Genetic Diversity Assessment of African Yam Bean (Sphenostylis stenocarpa (Hochst. Ex A. Rich.) Harms) Accessions in Ethiopia By Noel Ndlovu (R121740D) University of Zimbabwe Faculty of Agriculture Department of Crop Science A Research Project Submitted in Partial Fulfillment of the Requirements of the Masters of Science (MSc.) Degree in Crop Science (Plant Breeding) Supervisors: Prof. W. A. Gebresselasie, Dr. E. Gasura and Dr. S. Dari June 2019 DECLARATION UNIVERSITY OF ZIMBABWE FACULTY OF AGRICULTURE The undersigned certify that they have read and recommended to the Department of Crop Science for acceptance, the thesis entitled: MORPHOLOGICAL CHARACTERIZATION AND GENETIC DIVERSITY ASSESSMENT OF AFRICAN YAM BEAN (SPHENOSTYLIS STENOCARPA (HOCHST. EX A. RICH.) HARMS) ACCESSIONS IN ETHIOPIA Submitted by: NOEL NDLOVU in partial fulfilments of the requirements for the Master of Science (MSc) Degree in Crop Science (Plant Breeding) Approved by Supervisors: Prof. W. A. Gebresselasie: Date: 12 August 2019 Dr. E. Gasura…………………………......................................Date………………… Dr. S. Dari………………......…………………........................Date…………………. Department chairperson: Dr. E. Gasura…………………................................................Date…………………. ABSTRACT African Yam Bean (Sphenostylis stenocarpa (Hochst. Ex A. Rich.) Harms) (AYB) is an underutilized tropical leguminous plant which produces edible seed grain, leaf spinach and tubers. Africa yam bean possess a greater potential in alleviating food and nutritional insecurities facing Africa in the wake of climate change and its associated effects. However, limited research emphasis has been placed on the crop to establish the extent and magnitude of genetic diversity among the collected AYB accessions. Morphological characterization and genetic diversity analysis study was conducted on 169 AYB accessions sourced from the International Institute of Tropical Agriculture (IITA), Nigeria. The main objective of the study was to determine the extent of genetic diversity and assess trait inter-relationships among AYB accessions for utilization in future breeding and germplasm conservation. The field experimental trial was conducted during the 2018/19 agricultural season at the Ethiopian Institute of Agricultural Research (EIAR), Oromia Region, Ethiopia. The study was fitted into a 13 x 13 Alpha lattice design (0.1) with two replications. The morphological characterization experiment was conducted following the method of the IITA Reference Guide for AYB. Data was collected on quantitative and qualitative traits; and analyzed using R Studio Version 3.6.1, DARwin Version 6 and IBM SPSS Statistics Version 25 statistical packages. Analysis of Variance (ANOVA) indicated significant variations (p≤0.05) in AYB accessions for some morphological traits evaluated. The significant variations were observed on parameters; seed yield per plant, petiole length, terminal leaf length, days to 50% flowering and number of primary branches. African yam bean accessions with least and highest seed yield per plant recorded means of 22 g and 54 g respectively with accession TSs 357 as the highest yielder. Similarly, 100 seed weight varied widely across the studied accessions and recorded a mean value of 21.36 g. Seed grain yield per plant was highly correlated to terminal leaf length and width; and plant part pigmentation parameters. ii Furthermore, 100 Seed Weight was significantly correlated to terminal leaf length (r = 0.441), leaf colour (r = 0.72) and seed yield per plant (r = 0.862). The study further revealed that, there was a negative correlation between seed yield per plant and days to 50% flowering (r = -1.42). Principal Component Analysis (PCA) was performed to ascertain the main components explaining the total variation observed. The first five components accounted for 78.98% of total variation among accessions. The differential trait loadings on the first two PCs showed that, the delineation of diversity among accessions emanated from seed yield per plant, 100 seed weight, main stem pigmentation, primary branches pigmentation and petiole pigmentation parameters. Hierarchical clustering analysis based on seed grain parameters grouped the tested accessions into three major clusters (at 100% similarity level) and five sub-clusters (at 50 % level of similarity). The data was further classified into four sections using the Unweighted Neighbour-Joining method according to identified characters loading to the first five principal components. The present research proved the existence of significant genetic diversity and trait association among the studied accessions of AYB. The observed variation and inter-character association should be exploited for AYB genetic advancement and conservation. Keywords: Africa Yam Bean, Genetic Diversity, Hierarchical Cluster Analysis, Morphological Characterization, Principal Component Analysis, Unweighted Neighbour- Joining Method iii ACKNOWLEDGEMENTS I would like to start by giving special thanks to God Almighty for his everlasting love and favour that has sustained me through this journey. Secondly, I want to extend my profound gratitude to the GENES EU Intra-Africa Mobility Scheme for providing the financial and technical support needed for the swift execution of this project. I would also like to express my deepest appreciation to my research supervisors Prof. W. A. Gebreselassie (Jimma University, Ethiopia), Dr. E. Gasura and Dr. S. Dari (University of Zimbabwe) for their guidance and technical input throughout the course of the research tenure. Furthermore, I gratefully acknowledge the University of Zimbabwe and Jimma University for providing me with the necessary skills and tools in executing the various elements of the project. The Ethiopian Institute of Agricultural Research (EIAR) and International Institute of Tropical Agriculture (IITA) played a pivotal role in ensuring the success of the research and for that I am forever indebted to them. I would also like to extend my hand of appreciation to the Doyo Community Small Holder Farmers Group (Oromia Region, Ethiopia) who provided an ideal environment for me to settle and execute my due activities in their region. I would also like to shine light on Norman Munyengwa, Tedious Choga and Tatenda Mayaya for assisting me in attending to some local administrative procedures when I was out of Zimbabwe. I feel great pleasure to also acknowledge Suzzy Shitta Ndenum and Florence Simbota for their priceless efforts to make this work a success. Lastly, I would like to express my profound gratitude to my family for their unceasing support and belief in me. iv DEDICATION This research study is dedicated to my mother (Mrs. T. Ndlovu), father (Mr. D. Ndlovu) and siblings (Nicole and Nigel). I will always strive to put a smile on your faces. v TABLE OF CONTENTS DECLARATION.......................................................................................................................i ABSTRACT..............................................................................................................................ii ACKNOWLEDGEMENTS....................................................................................................iv DEDICATION..........................................................................................................................v TABLE OF CONTENTS........................................................................................................vi LIST OF TABLES..................................................................................................................ix LIST OF FIGURES.................................................................................................................x LIST OF APPENDICES.........................................................................................................xi LIST OF ACRONYMS.........................................................................................................xii CHAPTER ONE.......................................................................................................................1 1.0 INTRODUCTION............................................................................................................1 1.1 Background of the Study.............................................................................................1 1.2 Research Problem Statement.......................................................................................4 1.3 Justification.................................................................................................................5 1.4 Objectives....................................................................................................................6 1.4.1 Main Objective..................................................................................................6 1.4.2 Specific Objectives...........................................................................................6 1.5 Hypotheses...................................................................................................................7 CHAPTER TWO......................................................................................................................8 2.0 LITERATURE REVIEW.................................................................................................8 2.1 Africa Yam Bean: Background...................................................................................8 2.1.1 Taxonomy and botanical