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Abstract

Understanding the inheritance pattern, heterotic groups and inbreeding depression is the prerequisite for hybrid seed production in rice. Therefore, this study employed a full diallel mating design involving five diverse high-yielding rice genotypes, encompassing two tall-statured varieties and three medium-statured mutants. The results demonstrated statistically significant differences for for plant height, panicle length, tillers per plant, fertility percentage and grain yield. Heterosis was most pronounced for grain yield (24.2%), followed by tillers per plant (19.8%) and panicle length (19.2%). Conversely, inbreeding depression was lowest for tillers per plant (-11.5%) and grain yield (-6.8%). Additive-dominance model provided a good fit for tillers per plant and plant height, implying the significance of both additive (D) and dominance components (H1 & H2) in their genetic control. However, for panicle length, fertility percentage, and grain yield, the model provided a partial fit, indicating a more intricate genetic architecture involving both additive and non-additive genetic effects. Plant height and tillers per plant appear to be predominantly exhibited by additive genes, making them well-suited for improvement through pedigree selection strategies. Conversely, fertility percentage and grain yield seem to be more influenced by over-dominant gene effects, indicating the potential for exploiting hybrid vigor to enhance these traits in breeding programs. Moreover, high narrow-sense heritability (plant height: 84%, tillers per plant: 93%) and dominance of additive effects suggest significant potential for genetic improvement of these traits in rice breeding programs.

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