Tolerance to high temperature at reproductive stage: Trade-offs between phenology, grain yield and yield-related traits in wild and cultivated barleys

High-temperature stress at the reproductive stage poses a substantial constraint on cereal production worldwide. This study was conducted to assess tolerance to terminal high-temperature stress in 45 wild (Hordeum vulgare ssp. spontaneum) genotypes, four cultivars (H. vulgare ssp. vulgare), 98 F-3 and 79 BC1F2 families derived from hybridization of a high-temperature tolerant wild genotype and a susceptible cultivar 'Mona'. Results of analysis of variance showed significant genotypic and high-temperature stress effects on all the traits studied. Approximately one quarter of the wild genotypes originating from a warmer climate were slightly affected by high-temperature stress. Grain yield strongly correlated (p < .01) with stress tolerance, yield stability and heat tolerance indices. The reduction in the reproduction period caused by high temperature was much higher in cultivated genotypes than in wild ones. Grain number and weight were the most effective yield components to screen high-temperature tolerant F-3 and BC1F2 families. In conclusion, strategies like escape/avoidance are being used primarily to cope with heat stress by cultivars, whereas adaptive strategies such as tolerance are being implemented by wild barley.