Estimation of standard heterosis and heterotic grouping of elite sorghum [Sorghum bicolor (L) Moench] inbred lines under moisture stress conditions

Abstract

The development and selection of appropriate parents are prerequisites for sorghum hybrid variety development. The lack of a broad genetic base is the most significant constraint to sorghum crop improvement. The assignment of sorghum germplasm lines to appropriate heterotic groups is critical for increasing sorghum productivity. The experiment was conducted to determine the amount of standard heterosis and to categorize sorghum inbred lines into distinct heterotic groups. In the 2019 main cropping season, 42 sorghum genotypes were tested using an alpha-lattice design with two replications. Combined analysis of variance showed that there was a highly significant difference (p < 0.01) among the genotypes for all studied traits. The maximum grain yield was obtained from the hybrids 4x14 (6.32 tha^-1), followed by the hybrids 8x15 (5.92 tha^-1), 1x15 (5.88 tha^-1), 13x14 (5.78 tha^-1) and 6x15 (5.57 tha^-1), with an average value of 5.0 tha^-1. Similarly, the 4x14 hybrid exhibited a maximum grain yield with 30.71 % heterosis, which was greater than 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. Finally, based on yield performance, heterotic response and combining ability estimates for grain yield and its components, the hybrid crosses 4x14, 8x15, 1x15, 11x14, 11x15, 13x14, and 6x15 were found to be the most promising and potential hybrids that could be exploited commercially after critical evaluation for their superiority and yield stability across locations over the years.