Asian Research Journal of Current Science

This investigation was carried out to estimate the combining ability, genetic components and the nature of gene action using four sorghum lines [Cytoplasmic-Genetic Male Sterile (CGMS) Lines], three males (testers) and their 12 top crosses (developed through line x tester mating design) under 2 irrigation treatments (environments). Highly significant differences were found among environments, genotypes (parents and crosses), lines and line x tester interactions for all studied traits from combined data in both seasons (2018 and 2019). Line x tester x environment (L x T x E) interactions were also significant for all studied traits in both seasons except for, number of green leaves in 2018 season, suggesting that the top crosses between the lines and the testers differed from environment to another. The best top crosses were (L₁xT₃, L₂xT₃, L₃xT₃ and L₄xT₃) which significantly out-yielded the crosses means, which were also tolerant to drought (low DSI values). In this respect, four top crosses (L₁xT₃, L₂xT₃, L₃x T₃ and L₄xT₃) were the most promising hybrids with the maximum desirable heterotic values for all studied traits over mid and better parents in both seasons. One line (L₂) exhibited positive highly significant GCA effect toward 1000 grain weight and grain yield per plant in both seasons, and one tester (T₃) was considered to be excellent general combiner for plant height, No. of green leaves and out-yielding the testers mean in both seasons. The promising top crosses which showed excellent desirable SCA effects were obtained from (good x good), (good x poor), (poor x good) and (poor x poor) general combiners, indicating that both additive and non-additive gene actions played an important role in the expression of the studied traits. The magnitudes of additive genetic variances (σ²A) were larger than those of non-additive ones (σ²D) for all traits in both seasons, indicating that the additive gene action were pronounced in the inheritance of these traits. The magnitudes of variances σ2A x E interaction were greater than those of σ²D x E ones for all studied traits in both seasons, indicating that additive variance was more affected by the drought environment conditions than non-additive ones. The result of heritability estimates presented additional evidences about predominance of non-additive gene action in the inheritance of the studied traits. For that, crossing programme could be used for producing supper promising grain sorghum hybrids which can facing the water deficient conditions in the upcoming climatic changes scenario.