Evaluation of Combining Ability in Hybrid Rice (Oryza sativa L.) Parental Lines for Yield and Grain Zinc Concentration
P. Madhukar *
Regional Agricultural Research Station (RARS), Polasa, Jagtial – 505529, PJTAU, Telangana, India.
B. Srinivas
Regional Agricultural Research Station (RARS), Polasa, Jagtial – 505529, PJTAU, Telangana, India.
P. Gonya Nayak
Regional Agricultural Research Station (RARS), PJTAU, Telangana, India.
B. Laxmi Prasanna
Rice Research Unit (RRU), ARI, PJTAU, Rajendranagar, Hyderabad, India.
*Author to whom correspondence should be addressed.
Abstract
The present investigation was undertaken to assess the combining ability of selected cytoplasmic male sterile (CMS) lines and restorers for grain yield, yield-attributing traits and grain zinc concentration in hybrid rice. Analysis of variance for combining ability revealed highly significant differences among lines, testers and line × tester interactions for grain yield, grain zinc concentration and most yield-related traits, indicating substantial genetic variability among the parental materials. Both general combining ability (GCA) and specific combining ability (SCA) variances were significant for most traits. The GCA/SCA variance ratio indicated the predominance of additive gene action for days to 50% flowering and grain zinc concentration, whereas non-additive gene action predominated for grain yield and most yield components. Among the CMS lines, CMS 69B was identified as a superior general combiner for grain yield, while CMS 11B and CMS 64B were promising general combiners for grain zinc concentration. Among the testers, CR Dhan 411, IET 28713, IET 27984 and CR Dhan 315 exhibited desirable GCA effects for grain zinc concentration, with IET 28713 and IET 27984 also showing good combining ability for grain yield. Several hybrids exhibited significant positive SCA effects for grain yield and grain zinc concentration. Notably, CMS 64A × IET 28703, CMS 69A × IET 27984 and CMS 11A × IET 28701 showed promising performance for the simultaneous improvement of grain yield and grain zinc concentration. The findings indicate that heterosis breeding would be effective for enhancing grain yield, while selection-based breeding approaches could be utilised for improving grain zinc concentration. The identified superior parents and hybrids may serve as valuable genetic resources for developing high-yielding, nutritionally enhanced rice hybrids and warrant further evaluation in multi-location trials.
Keywords: Hybrid rice, combining ability, general combining ability, specific combining ability, line × tester analysis, grain yield, grain zinc concentration, biofortification, cytoplasmic male sterility, gene action