Genetic variation and morphological diversity in cowpea (Vigna unguiculata L. Walp)

Abstract

Cowpea is multipurpose pulse crop grown by poor and marginal farmers in arid zones of India. The extent of genetic diversity present in the cowpea accessions was studied for utilizing the most divergent parents for cowpea improvement programme. Genetic variability and genetic divergence was assessed in the 169 genotypes of cowpea using Mahalanobis D². High phenotypic and genotypic coefficient of variation, heritability and genetic advance were observed for days to 50 per cent flowering, number of branches per plant, number of pods per plant and seed yield per plant. The genotypes were grouped in to eight clusters, of which maximum intra cluster distance was exhibited by cluster VI and minimum by cluster II. The inter cluster distance was maximum between cluster II and IV. The genotypes from cluster II and IV, which have high and low cluster means for majority of the characters. The genetic advance estimates were medium to high (17.34% to 87.94%) for all the characters. seed yield contributed maximum towards the total diversity (48.05%), followed by days to 50 per cent flowering (21.08%), test weight (17.68 %), days to physiological maturity (3.58 %), plant height (3.49 %), pod length (1.69 %), number of clusters per plant (1.35 %), number of pods per plant (1.07 %), number of seeds per pod (0.75 %) lowest contribution was noted from number of branches (0.05 %)  per plant. Therefore, genotypes from same regions are not recommended for hybridization because of close genetic background which was evident from the result showing genotypes belonging to same cluster.