Genotypic Variation and Genotype × Environment Interaction for Yield‐Related Traits in Synthetic Hexaploid Wheats under a Range of Optimal and Heat‐Stressed Environments

Adaptation of wheat (Triticum aestivum L.) to high temperature could be improved by introgressions from wild relatives. The response of 137 D genome synthetic hexaploid wheats (SHWs) to high temperature was evaluated to determine their potential for wheat improvement. Field experiments were conducted in two temperature scenarios (normal sowing time [NOR] and late sowing time to expose the plants to heat stress [HS]) for 2 yr at three locations to assess the effect of terminal high temperature on yield‐related traits. High temperature stress overall led to a 46.9% reduction in grain yield and significant reductions of 25.2% in days to heading, 26.6% in plant height, 16.1% in grain number per square meter, and 18.3% in thousand grain weight. In ridge regression analysis, agronomic traits explained 8.74 to 35.2% of the variation in grain yield in the HS treatments with an average of 30.47%. In NOR treatments, agronomic traits explained 8.85 to 45.5% of the variation in grain yield, with an average of 34.5%. Days to heading was negatively correlated with grain yield in the heat‐stressed environments but did not explain significant variation in grain yield in optimal environments. Thousand‐grain weight explained the highest variation in grain yield in all environments, followed by grain number per square meter. The top ten highest grain‐yielding SHWs in the HS treatment were also tolerant to heat stress, with a heat susceptibility index ranging from 0.33 to 0.40. These SHWs could be a promising source to introduce yield‐related traits to develop high‐yielding wheat cultivars for heat‐stressed environments.