Variation, heritability and genetic advance of eight characters in white yam.

Phenotypic and genotypic coefficients of variation, heritability, and genetic advance were estimated for: time to vine emergence, leaf size, leaf virus infection, plant leafiness, shoot height, vine dry weight, number of tubers per hill and tuber yield per hill in white yam (Dioscorea rotundata Poir.) using plants recently derived from seedlings (SP) as well as those that have been clonally propagated for 3-5 years (CP). Estimates for these parameters were much lower in SP than in CP plants. Mean squares of characters in SP families were significant for leaf virus infection, plant leafiness, vine dry weight and tuber yield; and for all characters in CP except number of tubers per hill. Although in CP, heritability (%) was high for leaf size (67.8), plant leafiness (66.9) and fresh tuber yield (58.1), only tuber yield had a correspondingly high expected genetic advance (74.3%). The study indicated that rapid genetic advance can be achieved for tuber yield, under more uniform environment, by single plant selections followed by clonal propagation.