EN
Field investigation was carried out to study the genetic variability, heritability and genetic advance and the variability studies showed significant differences among the thirty genotypes for all the thirteen characters. Yield per plant was maximum in CL 4 genotype collected from Atchirupakkam in Villupuram district. The characters viz., number of vines per plant, sex ratio, days to first female flowers, node number of first female flower, days to fruit maturity and number of fruits per plant were recorded the maximum in the same genotype. Genetic analysis indicated maximum phenotypic and genotypic coefficient of variation for single fruit weight and 100 seed weight. The characters viz., fruits diameter, flesh thickness, number of fruits per plant and yield per plant, recorded highest estimate of PCV and moderate estimation of GCV. The characters viz., number of seeds per fruits, flesh thickness, number of primary branches and fruit diameter recorded moderate estimate of PCV and GCV. Lower estimation of GCV was observed for sex ratio, fruit length and number of male and female flowers. High heritability (broad sense) was observed for 100 seed weight, number of seeds per fruit, single fruit weight, vine length, fruit diameter, fruit length, flesh thickness, number of male flowers,sex ratio, yield per plant, number of primary branches per plant, number of female flowers and number of fruits per plant. Based on mean performance, CL 4 followed by CL 22 and CL 10 were selected as the best genotypes in watermelon for the costal ecosystem, by virtue of their higher yield combined with desirable component characters.