Post-flowering drought stress response of advanced breeding lines and cultivars in post-rainy season sorghum [Sorghum bicolor (L.)]

Abstract

Sorghum is a prominent cereal crop grown in dry and semi-arid regions of South Asia and sub-Sahelian Africa, where moisture stress is a significant constraint in the post-rainy (rabi) season. Sorghum grain yields are poor during post-rainy season because the crop is grown on residual moisture and suffers from moisture stress beginning in December, which coincides with the post-flowering growth period. Understanding the correlation between productivity and physiological characteristics is essential for breeding high-yielding cultivars of sorghum that can better withstand drought after flowering. In the current study, 52 genotypes consisting of 41 advanced breeding lines (16 RILs, eight NILs and 17 improved lines for yield) and 11 released varieties (landraces and elite cultivars) were evaluated for morpho-physiological and yield traits for two years (2018–19, 2019–20 post-rainy seasons) under well-watered (WW) and water stress (WS) conditions. Pooled data from two years showed a reduction in yield (22.84 %), green leaf area (58.09 %) and green leaves (48.01 %) under WS condition compared to WW condition, whereas epicuticular wax load increased under WS condition by 41.21 %. For the selection of the drought-tolerant genotypes, the trait green leaf area 30 days after flowering (GLA_30 DAF) was reliable based on rank correlation and PCA under WS conditions. Based on stability analysis, drought susceptibility indices, multi-trait stability index and the yield performance under WS condition, seven superior lines (SPV2544, PA, STG25, RL167, CRS65, BJV362 and STG44) were identified for post-flowering drought tolerance.