Assessing wheat genotype performance under heat, drought and combined stresses using multiple stress indices

As a crucial staple for millions, climate-resilient wheat genotypes are vital for safeguarding livelihoods and ensuring food security. The study encompassed 80 genotypes and was conducted during the Rabi seasons of 2019-2020 and 2020-2021. This study provides a comprehensive analysis of various stress indices to determine their effectiveness in predicting wheat genotypes performance under diverse environmental conditions. Based on strong positive correlation of indices with grain yield per plot along with insights from principal component analysis, our findings showed that the Stress Tolerance Index (STI), Mean Productivity (MP), Geometric Mean Productivity (GMP), Harmonic Mean (HM), and Yield Index (YI) are the most reliable indicators of yield performance under drought, heat, and combined stress conditions. This confirms their effectiveness in selecting resilient genotypes. Additionally, while these indices are robust in predicting performance, it is important to consider their trade-offs with yield stability under stress conditions to ensure a balanced approach in genotype selection. A negative correlation between yield stability index (YSI) and grain yield in favorable conditions suggests that genotypes with high yield stability prioritize consistency over maximum yield potential. The genotypes C-306, HD-2888, GW-477, RW-5, WH-1142, PBW-773 and HD-30 are identified as the best performers under these environmental conditions. The findings highlight the consistent and significant relevance of stress tolerance, stress susceptibility indices, reduction and relative stress index in both PC1 and PC2 explaining the majority of variance within all stress contexts. These revelations offer valuable insights for devising crop enhancement strategies aimed at elevating yield and productivity under diverse stress conditions. Moreover, this knowledge can guide the selection of parental lines for crafting new cultivars with heightened stress tolerance.