Selection of suitable wheat genotypes under thermal stress and complex genotype-environment interaction using stability analyses and selection indices

Thermal stress is a consequence of climate change that threatens food security, causes plant tissue damage, and harms crop production, particularly during the pollination and fertilization period and in grain-filling stages negatively impacting the number of grains, grain size, and quality. Genotype-environment interaction (GEN: ENV) complicates the selection of optimal wheat genotypes due to the complex genetic basis of yield under varying conditions. Diversified approaches were put forth in response to the pressing demand for simultaneous enhancements in high-yield performance combined with stability. This study investigates the selection of ideal wheat genotypes under thermal stress and complex GEN: ENV using stability analyses and selection indices to assess genotype performance and stability. Twenty wheat genotypes were evaluated across optimal conditions (OC) and thermal stress conditions (TSC) over three growing seasons with six ENVs. Results demonstrated significant GEN: ENV, revealing genetic variations in thermal tolerance. The additive main effects and multiplicative interaction (AMMI2) biplot indicated a combined variance of 99.00%, and eleven genotypes showed stable grain yield (GY) with six ENVs, three (G05, G09, and G17) were more stable. The G04, G05, G06, G09, and G18 genotypes were chosen for GY as perfect (stable and high-performance) genotypes by weighted average of absolute scores biplot (WAASB) and were also identified as the best genotypes group by WAASB-GY, with the exception of G18. Ten selection indices showed significant positive associations under GY_oc and GY_tsc, so they can be leveraged to detect the genotype's high yield of GY_tsc indirectly. The heritability, accuracy, and r_{gen: env} values for most indices were high, indicating a major role of the genotypic effect in their inheritance, with the exception of the stress-non-stress production index (SNPI) index. Out of the five that were examined by WAASB, G04, G05, G06, and G09 were the top-ranking genotypes by the multi-trait genotype ideotype distance index, either before or after removing variables. This suggests that they could be examined for validation stability measures. The findings of this study offer valuable insights for ENVs variety selection, facilitating the identification of improved cultivars and supporting the development of thermal stress-resilient breeding programs.