Phenotypic diversity within yam (Dioscorea spp.) germplasm collection in Uganda

Abstract A deeper understanding of the morphology of available germplasm is an indispensable initial step for yam genetic improvement and enhanced production in Uganda. However, there is limited information in Uganda on the diversity of yam. The objective of this study was to characterize the diversity of yam cultivars farmers have utilized for decades in Uganda together with germplasm recently introduced from West Africa using phenotypic traits. A germplasm collection of 291 genotypes was characterized based on 28 phenotypic variables. The phenotypic traits data were subjected to multivariate analysis using principal component analysis (PCA) and cluster analysis. Phenotypic traits assessed were informative and discriminating, with 62% of total variation explained among the first six principal components. Our results showed that the important phenotypic traits contributing to most of the variability among the genotypes were leaf characteristics, flowering characteristics, and tuber traits. In general, most genotypes collected within Uganda were identified with amorphous tuber shapes compared to material sourced from West Africa. Dendrogram generated using “ward” hierarchical clustering revealed two major clusters with few of the genotypes sharing similarities. The study has shown that there is ample phenotypic variability within the major yam genotypes in Uganda yam germplasm that can be used for genetic improvement. The results are also useful with regard to the identification and conservation of elite genotypes for future genetic improvement of yam in Uganda. More in-depth molecular and biochemical studies to further understand the diversity are recommended.