Combining Ability Analysis of Locally Adapted Sorghum (Sorghum Bicolor (L.) Moench) Landraces Under Moisture Stress Environments

Abstract Sorghum is a climate-resilient crop that plays a vital role in food and nutrition security in the semi-arid regions of Africa, including Ethiopia. However, climate change is increasingly affecting sorghum productivity, particularly during the flowering and grain-filling stages. Therefore, the current study was conducted to estimate the combining abilities and determine the nature of gene action in locally adapted sorghum landraces for grain yield and key agronomic traits. A total of 169 sorghum genotypes were evaluated using a simple alpha lattice design with two replications at two dry lowland agro-ecological trial sites during the 2020/21 main cropping season. Combined analysis of variance showed highly significant differences among genotypes for yield and agronomic traits, signifying the presence of substantial genetic variation within the tested materials. Based on mean performance, the highest grain yields were recorded in the hybrids ATX2783 × IS38312 (6.67 tha− 1), ATX2783 × ETSL100383 (6.40 tha− 1), ATX2783 × ETSL100007 (6.21 tha− 1), ATX2783 × ETSL101152 (6.16 tha− 1), and ATX623 × IS38341 (5.82 tha− 1). The overall mean yield of the hybrids was 4.32 tha− 1, which exceeded the average yields of both the parental lines and the check varieties. The inbred lines ETSL100016, ETSL100301, IS38428, and the tester TX2783B were identified as the best general combiners for earliness based on their performance in reducing days to flowering, whereas ETSL101866 and ETSL101845 ETSL100016, and IS38428 were recognized as the best general combiner parents for days to maturity, indicating their potential use in breeding early-maturing sorghum hybrids. Parental lines ETSL100097, ETSL100016 and IS38428 were identified as the best general combiners for plant height. Lines IS3834, IS38324, ETSL100007, ETSL100541, IS38312, and the tester TX623B were identified as the best general combiners for 1000-grain weight. Lines IS38312, ETSL100383, IS38341, ETSL100007, and ETSL101152 and the tester TX623B were identified as the best general combiners for the grain yield trait. The hybrids ATX2783 × Muyra-1, ATX623 × ETSL101851, ATX623 × Gemedi, and ATX623 × Adukara were identified as the best specific combiners for days to flowering, indicating their potential for developing early-maturing sorghum hybrids. The hybrids ATX2783 × IS38324, ATX2783 × ETSL101865, ATX2783 × ETSL100392, ATX623 × ETSL101845, and ATX2783 × ETSL100392 were identified as potential specific combiners for panicle exertion. The hybrids ATX623 × ETSL101851, ATX623 × ETSL100301, ATX623 × ETSL101843, and ATX2783 × ETSL100088 were recognized as the best specific combiners for the grain yield trait. The ratio of general combining ability to specific combining ability variance was less than unity for all the traits studied. This suggests the predominance of non-additive gene action in the inheritance of these traits. In conclusion, the high-yielding and drought-resilient hybrids ATX2783 × IS38312, ATX2783 × ETSL100383, ATX2783 × ETSL100007, ATX2783 × ETSL101152, and ATX623 × IS38341 could be harnessed for commercial use following confirmation of their stability and adaptability across years and locations.