Combining ability and gene action studies for various yield contributing traits in local cucumber (Cucumis sativus L.) of Jammu region

The present investigation was conducted at the Vegetable Research Farm, Division of Vegetable Science, FoH & F, Chatha, SKUAST-Jammu (J & K) during 2022-23 and 2023-24 and was aimed at evaluating the general and specific combining abilities among the existing germplasm and assessing the gene action of different quantitative characters in 8 × 8 half-diallel mating design to facilitate the formulation of a sound breeding programme in this crop with the objective of studying combining ability and gene action in cucumber genotypes for various horticultural traits. Combining ability analysis showed that the mean sum of square attributable to General Combining Ability (GCA) among parents were significant for all traits and Specific Combining Ability (SCA) among crosses were significant for all traits. Parents identified as good general combiners included CS-5 (days to first female flowering), CS-4 and CS-7 (node number at which first female flower appears), CS-1 and CS-8 (number of female flowers per plant), CS-4 (fruit length and fruit diameter), CS-1 (average fruit weight), CS-2, CS-1 and CS-5 (number of fruits per vine) and CS-1, CS-5 and CS-3 (fruit yield per vine and fruit yield/ha). Crosses identified as good specific combiners were CS-2 × CS-8 (days to first female flowering), CS-3 × CS-5 (node number at which first female flower appears), CS-6 × CS-8 (number of female flowers per plant), CS-5 × CS-8 (fruit length), CS-5 × CS-6 (fruit diameter), CS-4 × CS-7 (average fruit weight), CS-2 × CS-8 (number of fruits per vine) and CS-2 × CS-8 (fruit yield per vine and fruit yield/ha). Estimates of gene action revealed that for most traits such as days to first female flowering, node number of first female flower, number of female flowers per plant, fruit dimensions, weight, fruit yield per vine and yield per hectare SCA variances (σ²s) exceeded GCA (σ²g), suggesting that non-additive gene action dominates their inheritance. The GCA/SCA ratio was less than unity for the majority of traits studied, supporting the greater influence of non-additive gene action. This implies that hybridization or heterosis breeding would be effective for exploiting hybrid vigour in cucumber crops in the future.