Morphological variability of greater yam (Dioscorea alataL.) in Malaysia

Abstract

An assessment of morphological variation among 70 accessions of greater yam (Dioscorea alataL.) collected throughout Malaysia was made. Data of 47 morphological variables measured from the accessions were subjected to multivariate analysis using principal component (PCA) and cluster analysis (CA). The PCA results indicated that the characters contributing largely to the species variability were those related to the shape, size and flesh colour of underground tubers; shape and colour of aerial tubers; position, shape, size and vein colour of the leaves; petiole colour; shoot growth rate; and number of days for shoots to germinate. The two-dimensional plot of the first two PCs showed a separation between accessions of purple tuber groups and those of white tuber groups, but was unable to distinguish accessions according to tuber shape groups, i.e. irregular, oblong and round, as revealed by visual observation. The dendrogram of CA revealed four major groups ofD. alatain Malaysia, which supported the PCA grouping. This study demonstrated thatD. alatain Malaysia consists of numerous genotypes revealing wide inter- and intra-group variability.