Evaluation of genetic divergence in ashgourd (Benincasa hispida Cogn.)

Abstract

A research programme was carried out at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 1999- 2001 with the objective of assessing the genetic diversity 'present in a population of ashgourd genotypes. Twenty-five genotypes were evaluated adopting randomized block design with 3 replications. Genetic parameters, association among the characters, direct and indirect effects of characters on yield, D2 values and selection indices were estimated. Analysis of variance revealed significant differences for almost all the characters. Genotypic and phenotypic coefficients of variation were high for mean fruit weight, fruit yield per plant, flesh thickness and fruits per plant. Node to first male flower, vine length, fruits per plant, mean fruit weight, fruit yield per plant, fruit length, fruit girth, flesh thickness, 100- seed weight, seeds per fruit and dry matter content had high heritability coupled with high genetic advance. However high heritability and low genetic advance was noted for days to first male and female flower. High direct effect of days to first female flower, fruits per plant fruit length and fruit girth on yield indicate that selection based on the above components result in the improvement of yield per plant. Mahalanobis D2 analysis clustered the 25 genotypes into 8 groups with genotypes from different eco-geographic locations being grouped in the same clusters. The genetic distance was maximum between II and IV, while the minimum

-.----.~--- --- 2 divergence was between clusters VII and VIII. The character seeds per fruit contributed maximum to the total divergence. In future breeding programmes selection of parents from clusters II and IV for hybridization is likely to give the most heterotic hybrids. Fruit length and fruit girth can be used as the criteria for selection of genotypes since they had high direct effect on yield of the plant. There is a high scope of improvement for yield through selection since there exists high variation for the character along with high heritability and genetic advance.