Heterosis and combining ability analysis for growth, flowering and fruit yield characters in okra

Abstract

Twenty one F1 hybrids of okra produced by a 7 × 7 half diallel cross were evaluated along with their seven parents for studying heterosis and combining ability for growth, flowering and fruit yield. Analysis of variance for combining ability showed that the variances due to GCA and SCA were highly significant for all the studied traits, indicating the involvement of both additive and dominance types of gene action in the inheritance of these traits. Heterosis of F1 hybrids over the higher parent was estimated. The most heterotic combinations were Romi x Clemson Spineless, Balady Green x Balady Red, Balady Red x Clemson Spineless and Romi x Balady Green for yield. The hybrid Romi x Clemson Spineless exhibited heterosis of 13.31% in fruit yield per plant over the higher yielding parent. Combining ability analysis according to Griffing’s Method II, Model II revealed that Balady Red, Esmaily and Clemson Spineless gave high general combining ability effects for most of the traits. It was observed that the best cross combination in terms of SCA effects always involved one or both high general combiners as parents. The crosses Romi x Clemson Spineless, Dwarf Green Long Pod x Esmaily and Romi x Balady Red were found to be the best combinations for fruit yield per plant, earliness of flowering and number of fruits per plant, respectively. Genotypic and phenotypic correlations were calculated for fruit yield and its components among the parents and their F1 hybrids. Genotypic correlations were generally higher than those of phenotypic correlations suggesting an antagonistic effect of genotypes and environments on the phenotypic relationship between these traits. Fruit yield per plant showed significant and positive correlations with number of branches per plant and number of fruits per plant. This suggests that these two traits should be used as selection criteria in okra.