Genetic divergence in cluster bean (Cyamopsis tetragonoloba (L.) Taub.)

Abstract

The present study aimed at evaluating a collection of clusterbean (Cyamopsis tetragonoloba (L.) Taub.) genotypes for yield and related characters and grouping of genotypes was carried out at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during the period 2003-2004. Twenty nine genotypes of clusterbean were evaluated for yield and yield related characters in randomized block design with three replications. The analysis of variance revealed significant differences among the varieties for all the characters studied which include days to 50 per cent flowering, plant height, number of primary branches, number of pod clusters per plant, number of pods per cluster, pod weight, pod length, number of seeds per pod, number of pods per plant and yield per plant. High values of PCV with correspondingly high values of GCV were observed in the present study for number of pod clusters per plant, number of pods per plant, number of pods per cluster and yield, which indicated the existence of high degree of genetic variation and ample scope for improvement of these characters through selection. High values of heritability coupled with high genetic advance was observed for number of pod clusters per plant, pods per plant, pod yield and number of pods per cluster suggesting additive gene action for these traits. There is immense scope for improvement of number of pod clusters per plant and number of pods per plant through selection on account of their high magnitude of heritability and exceptionally high genetic advance. Vegetable pod yield showed high positive genotypic correlation with the characters number of pods per plant, number of seeds per pod, pod weight and number of pod clusters per plant. Path coefficient analysis revealed number of pods per plant and pod weight are the characters with high direct effect. These two characters had got high indirect effect on yield through number of pod clusters per plant and number of seeds per plant respectively. Hence these characters can be identified as the major characters contributing towards pod yield and selection based on these characters would be effective for developing high yielding varieties of clusterbean genotypes. Based on Mahalanobis statistic, the 29 genotypes of clusterbean were grouped into four clusters. Cluster II was the largest with 10 genotypes. Intercluster distance was observed maximum between clusters I and IV while the close proximity was noticed between the clusters II and III. Cluster IV having the single variety Ct 11 exhibited the maximum mean value for yield per plant, number of pods per plant and number of clusters per plant indicating that this cluster is superior to the others with respect to these characters. Cluster II having Ct 7 was superior for pods per cluster, pod weight and days to 50 per cent flowering. On the basis of selection index the genotypes IC 10350 (Ct 11) and IC 8423 (Ct 7) recorded highest index value. Hybridization of the superior genotype Ct 11 of cluster IV with Ct 7 of cluster II having high pod weight would be beneficial for evolving high yielding genotypes.