Development and selection of appropriate parents are prerequisites for hybrid variety development. The lack of a broad genetic foundation is the most significant constraint to crop improvement. The assignment of sorghum germplasm lines to appropriate heterotic groups is critical for obtaining useful heterotic patterns among germplasm lines in order to boost sorghum productivity. As a result, the experiment was carried out to determine the amount of standard heterosis in a line x tester mating design and to categorize sorghum inbred lines into distinct heterotic groups for yield and related parameters. In the 2019 main cropping season at Mieso and Kobo, 42 sorghum genotypes were tested using an alpha-lattice design with two replications. Combined analysis of variance showed that there was highly significant difference (p<0.01) among the genotypes for all studied traits. The maximum grain yield was obtained from a hybrid 4x14 (6.32 tha-1) followed by hybrid 8x15(5.92 tha-1), 1x15 (5.88 tha-1), 13x14 (5.78 tha-1) and 6x15 (5.57 tha-1). Hybrid, 4x14 recorded maximum grain yield with (30.71%) heterosis over the standard check (ESH-4) for grain yield. The two heterotic (A and B) groups were identified based on their specific combining ability effects whereas three heterotic groups were identified based on their general combining ability effects to develop superior hybrids from broad base and suitable parents. The selected genotypes are recommended as potential parents for sorghum hybrid breeding in moisture stress environments. Finally, based on mean yield performance, heterotic response and combining ability estimates for grain yield and its components, the hybrid crosses 4x14, 8x15, 1x15, 11x14, 11x15, 13x14, 6x15 were found to be the most promising and potential hybrids which could be exploited commercially after critical evaluation for their superiority and yield stability across the locations over years.

Keywords: Heterosis; Hybrids; Sorghum; Heterotic grouping; Combining ability