GENETIC DIVERGENCE ANALYSIS IN YARD LONG BEAN GENOTYPES (Vigna unguiculata)

Abstract

The present study was conducted in the experimental field of Hajee Mohammad Danesh Science and Technology University, Dinajpur during the period from March, 2012 to July, 2012. 48 yard long bean genotypes collected from different locations of Bangladesh were grown in a Randomized Complete Block Design(RCBD) with three replications. This was done mainly to study genetic diversity among the genotypes and correlation and path coefficient among the characters of the genotypes studied. Data were recorded on days to first flowering, pod length, number of pods per plant, number of pod bearing nodes per plant, number of seeds per pod, 100 seed weight, seed yield per plant, days to first harvesting, length of harvesting period and green pod yield per plant. The results of the experiment revealed that significant variations were present in all the characters studied. Among the yard long bean varieties, YB-465 showed the highest days for days to first flowering and harvesting time. The maximum pod length (56.43 cm) was found in Sabuj Sathi and highest yield (259.00g) per plant in the variety BD-1583. Phenotypic coefficient of variation (PCV) was higher than the genotypic coefficient of variation (GCV) for all the traits. The highest genotypic (26.70%) and phenotypic (28.16%) coefficient of variations were recorded in seed yield per plant. Heritability estimates were higher for days to first flowering, pod length, number of pods per plant, seed yield per plant, days to first harvesting and pod yield per plant. High heritability coupled with high magnitude of genetic advance in percent of mean was found in pod length, seed yield per plant and pod yield per plant. Correlation coefficient indicated that yield per plant had highly significant and positive association with days to first flowering, pod length, number of pods per plant, number of seeds per pod and days to first harvesting. Path coefficient analysis revealed that pod length had maximum positive direct effect on yield per plant. Using Mahalanobis’s D? statistics method, 48 genotypes were grouped into 6 divergent clusters. Maximum differences among the genotypes within the same cluster (intra cluster distance) was shown by cluster VI (42.21) followed by cluster TV (28.22) and minimum differences among the genotypes within the same cluster was shown by cluster V (16.64) followed by cluster III (19.97). Cluster IV and VI showed maximum inter cluster distance of 1076.74, and the lowest inter cluster distance was noticed between clusters II and III (49.04), indicating wide genetic variability. It is desirable to select accessions from clusters having high inter cluster distance and also with high vegetable pod yield as parents in the recombination breeding programmes. The cluster means were calculated for each characters and ranks were given based on scores obtained for all the 10 characters. Of the clusters, cluster III with 4 genotypes ranked first and appears to be the most potential group. Similarly, other clusters IV and VI were next in ranking order and can be utilized in future breeding program.