Numerical Taxonomic Studies of the East African Highland Bananas (Musa AAA-East Africa) in Uganda
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THE UNIVERSITY OF READING eborah A. Karamura D ● AAA-East Africa) IN UGANDA NUMERICAL TAXONOMIC Musa STUDIES OF THE EAST AFRICAN HIGHLAND BANANAS (Musa AAA-East Africa) IN UGANDA Deborah A. Karamura A thesis submitted for the degree of Doctor of Philosophy Department of Agricultural Botany January, 1998 ISBN : 2-910-810-31-3 STUDIES OF THE EAST AFRICAN HIGHLAND BANANAS ( NUMERICAL TAXONOMIC The printing of the thesis “Numerical taxonomy studies of the East African Highland bananas (Musa AAA- East Africa) in Uganda” was made possible with the support of the International Network for the Improvement of Banana and Plantain (INIBAP). In this regard, the role of Claudine Picq and Emile Frison is duly recognized. ISBN: 2-910810-31-3 Realisation CIRPAC - Printed in France © IPGRI 1999 Abstract i ABSTRACT The purpose of this study was to determine the variation pattern that exists in the East African Highland bananas (Musa AAA) grown in Uganda, estimate levels of dissimilarity caused by different growing conditions, and establish a flexible provisional classification and identification system. Techniques of numerical taxonomy were employed to determine the variation pattern and these included two different coefficients, three different clustering methods, principal component analysis and classificatory discriminant analysis. Sixty one morphological characters were employed to determine differences among the 238 accessions available for the study; 192 accessions were from the national banana germplasm collections, 46 were from farmers’ fields in selected sites. Phenetic classifications resulting from different analyses were compared with an independent subjective classification. The phenetic classifications agreed with the subjective classification with regard to the positions of the majority of accessions. Accessions which were inconsistently placed in the cluster analyses were classified by classificatory discriminant analysis and 84 clones were identified. It was advantageous to compare different methods because they often gave complementary results. For example the comparison of cluster analysis versus principal component analysis revealed similar clusters of accessions in the phenograms and along the first four principal components. The East African Highland bananas have been kept as a subgroup within a Group (Musa AAA) as defined by the International Code of Nomenclature for Cultivated Plants. The smallest distinguishable units in the subgroup are clones and they have been grouped into clone sets. In summary four categories have been adopted in the classification of the East African Highland bananas; Group, subgroup, clone set and clone. Five clone sets were delineated, based mainly on qualitative characters. The clone sets were distinct enough for new accessions to be fitted into them. Beer and Musakala were very distinct from each other and from the rest of the clone sets. Nakabululu, Nfuuka and Nakitembe were least distinct from each other. These data can now be used to develop hypotheses concerning the evolutionary background of the East African Highland bananas and to exploit vigour, pest and disease resistance in the representative clones of the different clone sets proposed. Acknowledgements This work has been possible by the financial support of the Rockefeller Foundation to which I am very grateful. In this connection, I am indebted to Dr. John Lynam who has been a strong pillar in this work. My sincere appreciation and special thanks go to Dr. B. Pickersgill for her guidance on all the technical aspects of this thesis. The staff of the School of Plant Sciences, Reading, in particular Dr. T. Hedderson and Dr. A. Culham were of tremendous assistance during the preparation of this thesis. Data gathering was carried out at two genebanks, Kawanda and Kabanyolo Agricultural Research Institutes. I am most grateful for the support rendered to me at the two Institutes. Dr. D. Vuylsteke and Dr. C. Gold deserve special thanks for their advice, guidance and all the supervision of the practical aspect of this Thesis. The field work support was provided by the International Institute of Tropical Agriculture (IITA) and National Agricultural Research Organisation (NARO), Uganda. In this connection my thanks go to Dr. Cliff Gold, Dr. Eldad Karamura and their staff at Kawanda who provided both field labour and technical guidance for the project. I would like to acknowledge the support and assistance provided by Mr. Andrew Kiggundu during this same period, in addition, the contributions of Mr. Michael Walyawula, Mr. Z. Kiwanuka, Ms. Alice Nanyonjo, Ms. Edith Kiwanuka and Mr. Gerald Kyeyune are deeply appreciated. Thanks also go to Prof. E.A. De Langhe, Prof. R. Swennen (INIBAP), Dr. H. Tézenas du Montcel and Dr. X. Perrier (CIRAD) who gave their time to discuss the various aspects of tackling the problem of identification and classification of this crop. I am grateful to Dr. Gareth Davis who translated the major French papers related to the topic of this Thesis. Thanks go to Ms. Sheelagh Warren who read through some of the transcripts of this Thesis. I am very much indebted to my family who have waited so patiently to enable me complete this work. This work would not have been possible without the collaborative arrangements between IITA, NARO and The University of Reading. To my husband, Eldad Karamura, children: Elizabeth, Georgina, Phillip and Timothy Table of contents iii Table of contents Chapter 1 GENERAL INTRODUCTION Background ______________________________________________________________1 Bananas in East Africa ______________________________________________________2 Current problems in banana production ________________________________________4 Banana germplasm collections________________________________________________6 Research objectives ________________________________________________________7 Chapter 2 EVOLUTIONARY AND TAXONOMIC BACKGROUND OF BANANAS Banana classification and distribution __________________________________________9 Evolution of cultivated bananas ______________________________________________10 Introduction of bananas to Africa ____________________________________________11 Taxonomic studies of Musa species __________________________________________14 Chapter 3 ACCESSIONS, CHARACTERS AND DATA ANALYSIS Introduction ____________________________________________________________23 National banana collections ________________________________________________23 Accessions studied ________________________________________________________25 Character selection and scoring ______________________________________________29 Data analysis ____________________________________________________________38 Chapter 4 MULTIVARIATE ANALYSES OF KAWANDA BANANA GERMPLASM COLLECTION Introduction ____________________________________________________________45 Multivariate analysis of accessions of different genome groups ____________________46 Materials and methods ____________________________________________________46 Results ________________________________________________________________46 Discussion ______________________________________________________________51 Multivariate analysis of the East African Highland bananas in Kawanda banana germplasm collection-Material and methods____________________52 Results ________________________________________________________________52 Cluster analyses __________________________________________________________53 Phenetic versus subjective classification ______________________________________53 Principal component analysis________________________________________________63 Discussion ______________________________________________________________70 Chapter 5 MULTIVARIATE ANALYSES OF ACCESSIONS IN THE TWO UGANDA NATIONAL BANANA COLLECTIONS Introduction ____________________________________________________________73 Materials and methods ____________________________________________________73 Results ________________________________________________________________75 Cluster analyses __________________________________________________________75 Principal component analysis________________________________________________82 Discriminant analysis ______________________________________________________84 Discussion ______________________________________________________________87 iv Numerical taxonomic studies of the East African Highland bananas (Musa AAA-East Africa) in Uganda Chapter 6 ESTIMATION OF NUMBER OF DISTINCT CLONES IN THE TWO UGANDA NATIONAL BANANA COLLECTIONS AND PROPOSED COMPOSITION OF A CORE COLLECTION Introduction ____________________________________________________________91 Materials and methods ____________________________________________________92 Results ________________________________________________________________92 Accessions known to be ramets ______________________________________________92 Accessions sharing the same names __________________________________________92 Similar accessions which do not share names __________________________________103 Probable synonyms and distinct clones ______________________________________112 Discussion ____________________________________________________________118 Proposal for the establishment of a core collection of Ugandan Highland bananas ____________________________________________119 Chapter 7 STUDIES OF BANANA CLONES IN FARMERS’ FIELDS Multivariate analysis of farmers’ clones together with the reference collection ______129 Materials and methods ____________________________________________________129 Results ________________________________________________________________135