Evaluation of agronomic and physiological traits associated with high temperature stress tolerance in the winter wheat cultivars

Post-anthesis high temperature stress is a major concern for the winter wheat producing areas in east China, especially in Shandong province. Fourteen agronomic and physiological traits were studied in 58 Chinese wheat accessions under high-temperature conditions in 2012 and 2013. High temperature stress led to reduction in grain yield and other yield component traits. Significant variations were observed for grain yield per plant (GYPP), grain weight per spike (GWS), thousand kernel weight (TKW), grain number of the main-spike, spikelet number and biological yield per plant. Among the physiological traits measured, chlorophyll content and normalized difference vegetation index showed significant variation under high temperature stress. The results indicate that heat susceptibility index estimated for TKW, GYPP, GWS and flag leaf senescence scale (FLSS) could be used as selection criteria for identifying heat tolerant genotypes for the Shandong province. The results also suggest that FLSS is a good, quick visual indicator of stay-green for field selection for heat tolerance. After harvest, TKW can be measured as final indicator of heat tolerance. The varieties Gaoyou 9415, Hemai 13, Jimai 22, Kexin 9, Shannong 8355, Taishan 23, Yannong 5286 and Zimai 7 were heat tolerant and potential germplasm for heat tolerance breeding in Shandong province and other parts of China. The results could be useful for breeding climate resilient varieties for China or other countries in the world suffering high temperature stresses during grain filling period.