ABSTRACT

Thirteen collections of white yam (Dioscorea rotundata Poir) (Abbi, Obiaoturugo, Nwopoko, DRN/UYT/053, DRN/UYT/194, DRNIUYT/001, DRNIUYT/095, DRN/UYT/094, DRNIUYT/92A, DRN/UYT/052, DRN/IJYTIO44, DRN/UYT/094 and DRN/EJYT/085), were screened in the field at the Western farms of the National Root Crops Research Institute, Umudike, for tuber yield and some Morphological and Agronomic characters. The design was Randomized Complete Block Design (RBCD) with 6 replications. Variations were observed in both the yield and the characters studied. Genotype was found to be significantly different (P

<0.01) in tuber yield and all the characters studied, except in number of tubers per plant, percentage stand at harvest and number of tubers per plot. Fresh tuber yield conelated positively (P ><0.05) with all the characters studied. Multiple regression analysis, however, showed that length of tuber, plant height at 6 months after planting (MAP), leaf area index at 4 MAP, leaf area duration, diameter of tuber, number of leaves at 2 MAP and number of leaves at 6 MAP regressed negatively with tuber yield. Estimates for genetic coefficient of variation, phenotypic coefficient of variation and heritability, were high for leaf area index at 2 MAP, leaf area index at 4MAP and leaf area ratio. Path coefficient analysis revealed that leaf area index at 6 MAP had the highest direct influence on the tuber yield (P = 1.434). Correlated Response and Expected Genetic advance were high for weight per tuber, number of leaves at 2 MAP and number of leaves at 4 MAP. Based on the observed result, it is suggested that weight per tuber, leaf area index at 6 MAP, number of leaves at 2 MAP, number of leaves at 4 MAP and leaf area duration if selected for can lead to short term improvement in tuber yield. >