On farm conservation of Musa diversity in the great lakes region of East Africa

Banana (Musa spp.) cultivar diversity in the Great Lakes region of East Africa has been on the decline for the last several decades. A number of abiotic, biotic and socio-economic factors are thought to be responsible for this decline. In spite of low variation with respect to stress resistance, a number of farmers have continued to maintain a diversity of the local landrace highland banana cultivars in small plots. However, it is largely unknown whether farmers understand the value of banana diversity. If diversity is to be conserved and utilised, its value to farmers must be understood. Studies to assess diversity on farm were carried out in four benchmark sites in Uganda and Tanzania. The objectives of the study were to estimate levels of Musa diversity within and between benchmark sites; understand diversity trends over time in respect to changes in diversity within national genebanks and finally assess the usefulness of numerical methods in diversity assessment of a wider Musa genepool. Cultivar diversity per farm per site was assessed in 135 households and then compared with cultivar diversity in the national collections. Morphometric data was then taken from 135 sampled farms. Altogether, 257 accessions were studied; 125 from the national collection, and 132 from on farm. A total of 60 characters were used to measure diversity in the sampled household farms and the national collections. Two coefficients were used to measure diversity, group average clustering and principal component analyses were used to analyse similarity or dissimilarity among different groups of bananas and between different cultivars of the East African highland bananas. There was variation in cultivar diversity per site. The percentage variation explained by the first major components did not exceed 20% and these were able to separate genome groups. Within the highland bananas, clusters corresponding to clone sets were not very distinct in the first run of the analyses due to overlap. Thus, distinct clusters of the East African highland bananas were only observed in the second run of the analyses. Diversity varied in sites, and also between sites and national Musa collections due to different selection criteria and needs of different stakeholders. The level of viability between groups is demonstrated to be great but small within subgroups and this morphological diversity can be linked to utility of these traits by the farmers. Key Words: Cluster analysis, cultivars, morphometric data, principal component analysis RESUME La diversité des variétés des bananes dans la région des grands lacs de l'Afrique de l'est a été en déclin pour plusieurs dernières décennies. Un nombre des facteurs abiotiques, biotiques et socio économiques sont pensés être responsables pour ce déclin. Malgré la faible variation avec respect a la stresse de résistance, un nombre des fermiers a continué à maintenir une diversité des variétés locales des races de terre de banane des régions de montagne