Studies on genetic diversity in okra (Abelmoschus esculentus L. Moench)

Abstract

Okra is a popular green vegetable crop grown in India for its delicious tender pods. The extent of initials genetic variability or genetic diversity determines the level of crop improvement to large extent. Hence, the investigation on genetic variance was carried out with 44 okra genotypes. The high GCV and PCV were observed for plant height, internodal length, first flowering node, first fruit producing node, average fruit weight and number of seeds per fruit. High heritability coupled with high GAM were observed for all the characters, studied, except for days to 50% flowering and days to 80% maturity showed high heritability with low GAM. In genetic divergence study, 44 okra genotypes had differed significantly for the 12 quantitative morphological characters and grouped in to 12 clusters based on D2 analysis. The cluster III was the largest with eight genotypes followed by cluster I and VIII with seven, cluster II with five, cluster XII with three genotypes while, cluster IV, V, VI, IX, X and XI were included two genotypes each. Maximum inter cluster distance was observed between the cluster VI and VIII (35.57) and inter cluster distance as in cluster XII (28.14). The characters namely days to 50% flowering (35.62%), 100 seed weight (28.44%), number of seed per fruit (17.23%) and average fruit weight (8.14%) were directly contributed towards maximum divergence. The extent of genetic diversity at molecular level was estimated for 44 okra genotypes using DNA markers (RAPD). The total genomic DNA was extracted and subjected to RAPD analysis using 14 arbitrary decamer primers, produced good polymorphic bands across the genotypes. RAPD data’s were subjected to calculate a SED matrix using Wards method. It clearly showed two major groups, first consisting of three genotypes and second one further grouped in to 11 sub groups included 41 genotypes. The present study also clearly grouped the six wild species in one cluster and five cultivated species in another cluster from the total of eleven okra genotypes; these results were hold good with by using ITS markers.