Title: Formation of new rice breeding population with the aim of early maturity, high yield potential, and desirable quality
Author: Mostafa Modarresi
Eight rice genotypes, including Binam, Hashemi, Deylamani, TH1, Hasani, Saleh, Line23, and Gohar, were crossed in a line tester mating design in order to generate breeding populations, assess the combining ability, determine the nature and magnitude of gene actions, and estimate heterosis and heritability. The 23 genotypes (15 F1s and their parents) were evaluated in a randomized complete block design with three replications at the Rice Research Institute of Iran during the 2020 cropping season. The analysis of variance revealed significant genotype effects for all the investigated traits. The results indicated that additive gene action controlled plant height, grain length, grain width, and the grain shape. Meanwhile, non-additive gene action controlled panicle length, flag leaf length, flag leaf width, flag leaf area, number of panicles per plant, last internode length, panicle exertion, number of days to 50% flowering, number of days to maturity, grain weight per panicle, number of grains per panicle, number of filled grains per panicle, number of empty grains per panicle, panicle fertility, number of primary branches per panicle, awn length, and yield. Gohar proved an excellent general combiner for increasing panicle length, flag leaf length, leaf area, number of filled grains per panicle, panicle fertility percentage, and 100-grain weight when the parents’ general combining ability was evaluated. In addition, Hasani and Saleh demonstrated good general combiners for early maturity. The hybrids of Gohar were the best specific combiners to enhance yield components and displayed the highest heterosis in these traits. Hashemi × Gohar and Binam × Line23 were the best specific combiners to increase grain yield. Hashemi × Gohar and Hashemi × Saleh hybrids exhibited positive heterosis for grain yield. Between 2,000 and 3,500 plants were planted per population in 2021 as the F2 generation. A total of 1,521 plants were selected based on certain traits such as plant height, ideal plant type, seed appearance, and the findings of line × tester analysis.
Keywords: Combining ability, Gene action, Heterosis, Line by tester mating design, Rice