Study of genetic divergence for yield and quality traits in cowpea [Vigna unguiculata (L.) walp.]

The genetic divergence analysis was done using Mahalanobis D² statistics. The mean intra-cluster and inter-cluster D² values are compared for drawing conclusions on superiority of cowpea genotypes for various plant yield and quality attributes.

In the field of Vegetable Research Farm of Department of Horticulture, RPCAU, Pusa, Indiaduring 2018–19 (Rainy season) thirty-three cowpea genotypes were taken for genetic divergence analysis. The genotypes exhibited marked divergence and thus grouped into clusters following Tocher's method of clustering. The mean intra-cluster and inter-cluster D² values among the clusters were compared for their superiority of yield and quality attributes.

All the selected genotypes displayed marked divergence. Among the five clusters, cluster I consisted eight, cluster II had three, cluster III had eleven, cluster IV had nine and cluster V had two genotypes. The clustering pattern had no parallelism between genetic diversity and geographical distribution, suggesting that the selection of parental genotypes for hybridization will be more appropriate based on genetic diversity. The intra-cluster D² values ranged from 0.00 in cluster II, cluster III, cluster IV and cluster V to 16.12 in cluster I. The inter-cluster D² values revealed that highest inter-cluster generalized distance (44.50) was between cluster V and cluster III, while it was the lowest (20.12) between cluster II and cluster I. From this study it can be concluded that for selection and heterotic recombinants emphasis may be given to attributes such as seed germination percentage, peduncle length and average pod weight to enhance the yield of cowpea. Similarly, with respect to the clusters for obtaining the heterotic recombinants, genotypes placed in cluster V, cluster II and cluster III may be used in the crossing program.