Morphological variability within the Kenyan yam (Dioscorea spp.)

Abstract

Objective: To characterize 43 Kenyan yam cultivars using morphological characters. Methodology and results: Yam cultivars were collected in the major yam growing districts in Kenya. Data of 17 morphological variables measured on these accessions were subjected to multivariate analysis using Principal Component Analysis (PCA) and clustering criterion. The results indicated that the characters contributing most to variability were twining direction, stem colour, spine shape, leaf type and presence or absence of flowering for above ground plant parts; and tuber flesh colour, skin colour, shape of the tuber, hardness of the tuber when cooked, and presence or absence of roots on the tuber surface for the parts below ground. The pruned dendogram generated through agglomerative hierarchical clustering based on the similarity matrix revealed four main groups of this species. One group had only one cultivar which was collected in only one locality in Meru. This is possibly a newly discovered cultivar that has not been previously documented. Conclusion and potential application of findings: This study has showed that there is wide variability in the major yam cultivars grown in Kenya and this can be used to breed higher yielding varieties or screen for cultivars resistant to pests and diseases. The results would also be useful for conservation planning and genetic improvement of the crop. Nevertheless further confirmatory research is required using molecular tools to analyze the diversity detected