Dissecting gene action for yield traits in rice using Line × Tester analysis

Rice (Oryza sativa L.) production is increasingly threatened by abiotic stresses, notably salinity and phosphorus (P) deficiency which constrain crop performance in vulnerable agro-ecosystems. The current study was designed to assess the combining ability of four Saltol 1 introgressed backcross inbred lines and two Pup1 introgressed testers through a Line × Tester mating design with the objective of identifying the nature of gene action of yield traits and superior parental genotypes and cross combinations for the genetic enhancement under stress-prone conditions. Eight F₁ hybrids along with six parental lines were assessed using a randomized complete block design with two replications during Rabi 2023-24. Analysis of variance revealed considerable genetic variability across all the traits studied. Combining ability analysis demonstrated that BIL 33, D5-1-3-2-1 and C16-1-2-8 were superior general combiners, particularly for grain yield and associated component traits while cross combinations such as BIL 33 × C16-1-2-8 and BIL 1102 × D5-1-3-2-1 exhibited significant specific combining ability effects reflecting the yield potential of hybrids. Variance component analysis further indicated that traits such as days to 50% flowering, plant height and grain yield were chiefly administered by additive gene action whereas traits viz., flag leaf length, spikelet fertility and grain number were influenced by non-additive action. These findings provide valuable insights into the genetic construction of key agronomic traits and offer a strong basis for breeding stress-resilient, high-yielding rice hybrids.