Influence of Gca and Sca on Sorghum Parental Selection: Based on Progenies' Performance

Choosing elite sorghum parents and hybrids based on the general combining ability (GCA) and specific combining ability (SCA) is an effective hybrid breeding approach. The GCA contributes in offering demarcation on the average performance of parents in cross combination from the deviation of half-sib families targeting homozygous dominance. On the other hand, the SCA assists in providing responses about cross combination betterment from the covariance of full-sib families intended heterozygous dominance in the hybrid. As a result, both GCA and SCA offer valuable perspectives on hybridization. The aim of this study was, to pinpoint the role that GCA and SCA play in parental selection and identification of desirable cross combination based on the progenies' performance using line x tester mating in alpha lattice design. As indicated by lower than unity of predictability ratios (δ ² GCA/δ ² SCA) and low narrow-sense heritability (h ² ) values, the non-additive gene effects and environmental factors contributed significantly to the observed variations. Consequently, it is recommended that the selection procedure for exceptional individual plants should prioritize individual cross-performance. This approach would help ensure that the selected plants possess the desired traits due to non-additive genetic differences and are better equipped to withstand the environmental variability that affect trait expression. The GCA and SCA of five quantitative traits were examined for 38 crosses using the resultant of 2 lines and 19 testers with two standard checks at four locations. Results showed significant differences in GCA and SCA among parents and crosses. Six testers and one line were identified as the best general combiner by merit of significant negative GCA effects for plant height, resulting in short hybrids. The tester, Melkam has been found as a top general combiner for yield-enhancing traits, but it may also produce mid-maturing long hybrids. The three crosses PU209A/ICSR 14, PU209A/PRL 984182, and PU209A/PRL 984422 showed significant negative SCA effects in desired direction for days to 50% flowering, plant height and days to maturity. Four hybrids (PU209A/Birhan, PU209A/Meko, ATX623/PRL 020962 and PU209A/PU304) had high positive SCA effects for grain yield per hectare, which obtained by cross combination of good x poor GCA values in either direction. These results reflect the effects of polygenic variations, which are significant contributors to the expression of heterotic hybrids. Hybrid vigor can be achieved by crossing parents with different GCA values using various genetic processes. The degree of genetic distance affects the level of hybrid vigor achieved. This method of hybridization is useful in increasing production and profitability in agriculture.