Diversity and drought indices analysis reveals potential sorghum accessions for post-flowering drought stress tolerance

Abstract Drought is a significant limitation to crop production in sub-Saharan Africa, with the response of sorghum genotypes to pre- and post-flowering drought stresses varying. In Ethiopia, post-flowering drought has a significant impact on yield reduction. The study aimed to evaluate the response of 216 sorghum accessions to post-flowering drought stress and non-stress regimes. The experiment was conducted using a row-column design with two replications at Melkassa and Werer Agricultural Research Centers in Ethiopia. Results from both sites showed a significant difference among accessions in post-flowering water-stress and well-water regimes, indicating diversity among the tested accessions. While the phenotypic variance was higher than the genetic variance for all characters under study, most characters were less influenced by the environment due to the narrow range of difference. Drought tolerance index analysis identified stress tolerance index, mean productivity, geometric mean productivity, harmonic mean productivity, and yield index as appropriate indices to select post-drought tolerant sorghum accessions. Selection by these indices can help identify a genotype with desirable yield in both stress and non-stress conditions. Cluster analysis showed that accessions tended to group into four clusters: post-drought tolerant, semi-tolerant, semi-sensitive, and sensitive, based on significant associated indices. Acc#222888, Acc#28546, and Acc#216739 were identified as potential sources of genetic material for post-drought tolerance in both research sites. The study highlights the importance of evaluating sorghum genotypes for post-flowering drought resistance under different irrigation conditions to identify potential sources of genetic material for breeding programs aimed at developing drought-tolerant sorghum varieties.