Gene Action and Combining Ability Studies for Grain Yield and its Related Traits in CMS Based Rice Hybrids Using Line × Tester Analysis

The present study intends to estimate the nature and magnitude of gene action and combining ability for yield and related traits in CMS based rice hybrids developed by crossing three CMS lines with 14 testers in Line × Tester mating design. During kharif 2023, 42 F1’s were developed which were evaluated along with their 17 parents in Randomized Block Design (RBD) with three replications during kharif, 2024 at the Rice and Wheat Research Centre, Malan, Himachal Pradesh. The observations were recorded for various characters viz., days to 50% flowering, days to 75% maturity, plant height at maturity, effective tillers per plant, panicle length, spikelets per panicle, grains per panicle, grain yield per plant, spikelet fertility, 1000-grain weight, grain length, grain breadth and L:B ratio. The analysis of variance for combining ability showed that Lines × Testers had significant differences for all the characters studied which indicated presence of sufficient amount of variation for yield and its component traits. Combining ability analysis revealed that among testers, HPR 2143 and among lines, IR 58025A exhibited desirable general combining ability (GCA) effects for grain yield and majority characters. IR 58025A × HPR 2612 reflected desirable significant specific combining ability (SCA) effects for majority characters studied. Preponderance of non-additive gene action was found in the inheritance of characters which was validated by higher values of SCA variances than their corresponding GCA variances. The study revealed the potential parents and promising cross combination(s) which could be further exploited for heterosis breeding. However, Multi-environment trials will be needed for efficient selection because they help to understand the true genetic potential of genotypes.