Eight rice genotypes, including Binam, Hashemi, Deylamani, TH1, Hasani, Saleh, IR75479-199-3-3, and Gohar, were crossed in a line tester mating design to generate breeding populations, assess the general and specific combining ability (GCA and SCA) and identify suitable combinations for yield. 23 genotypes (15 F1s and eight parents) were evaluated in a randomized complete block design with three replications at the Rice Research Institute of Iran during the 2020 cropping season. Analysis of variance revealed significant genotype effects and GCA and SCA mean square values for all the investigated traits, which indicated the genetic diversity of the parental genotypes and the importance of both additive and non-additive gene effects in the inheritance of the studied traits. Results indicated that additive gene action controlled plant height. Meanwhile, non-additive gene action controlled panicle length, number of panicles per plant, heading date, hundred-grain weight, number of grains per panicle, and grain yield. Effects of general combining ability were significant for the panicle length, the number of panicles per plant, heading date, hundred-grain weight, number of grains per panicle, and plant height in all testers. Hasani and Saleh's genotypes demonstrated to be good general combiners for early maturity. Gohar was the best specific combiner to enhance yield components. Hashemi×Gohar was identified as the best combination for improving grain yield and reducing the number of days to heading. The predominance of non-additive types of gene actions related to grain yield and its components suggested that selecting the best plants should be postponed to advanced generation.
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