Combining Ability Analysis and Nature of Gene Action for Yield, Oil Content and Associated Quantitative Traits in Linseed (Linum usitatissimum L.)

Abstract

Aims: The present investigation was undertaken to estimate the general combining ability (GCA), specific combining ability (SCA), and nature of gene action governing seed yield, oil content, and associated quantitative traits in linseed (Linum usitatissimum L.), and to identify superior parents and cross combinations for future breeding programmes. Study Design: Line × Tester mating design. Place and Duration of Study: The experiment was conducted at the Oilseeds Research Station, Latur, Maharashtra, India, during the rabi season of 2025–26. Methodology: Seven genetically diverse lines were crossed with six testers using the Line × Tester mating design to produce 42 F₁ hybrids. The experimental material, comprising 13 parents, 42 F₁ hybrids, and one standard check, was evaluated in a randomised block design with two replications. Observations were recorded for ten quantitative traits: days to 50% flowering, days to maturity, plant height, number of branches per plant, number of capsules per plant, number of seeds per capsule, harvest index, 1000-seed weight, seed yield per plant, and oil content. Combining ability analysis was conducted following the method proposed by Kempthorne (1957) to estimate GCA and SCA effects and determine the nature of gene action. Results: Analysis of variance revealed significant differences among the genotypes for all the traits studied, indicating substantial genetic variability. Significant GCA and SCA variances were observed for most traits, demonstrating the involvement of both additive and non-additive gene effects in their inheritance. Among the parents, T-397, RLC-198, RLC-197, JLS-95, and RL-18123 were identified as superior general combiners for different economically important traits. The crosses OL-2013-14-2026 × BLS-2023R-20, NL-421 × BLS-2023R-19, LCK-2431 × JLS-95, and OL-2022-23-5 × BLS-2022R-30 exhibited desirable specific combining ability effects for seed yield and related traits. The results indicated the predominance of additive gene action for certain traits and non-additive gene action for others, suggesting the usefulness of both selection and hybridisation in linseed improvement. Conclusion: The identified superior general combiners and specific cross combinations constitute valuable genetic resources for developing high-yielding linseed cultivars with improved quality. The findings provide useful information for selecting suitable parents and adopting appropriate breeding strategies for the genetic improvement of linseed.