Response of Bread Wheat Genotypes to Heat Stress

Fifty-eight spring wheat genotypes were evaluated for yield and yield component traits. these traits are flag leaf area, plant height, heading to date, spikes per plant, 1000-kernel weight, and grain yield. this study evaluated wheat genotypes of diverse origins for three sowing date treatments during three seasons, to assess the heat stress tolerance of these genotypes under nine environmental conditions. genotypes were sown on first november (early), middle november (medium) and middle december (late) during the winter seasons of 2009/2010, 2010/2011 and 2011/2012 at sohag university experimental farm, egypt. analysis of variance revealed that all of these traits were significantly affected by genotypes, heat stress treatments, and years. the results of this study indicated that six wheat genotypes could be selected to grow under heat stress conditions. optimum sowing in the middle of november resulted in a better performance of genotypes than early and late sowing. grain yield was reduced under heat stress, therefore highlighting the importance of breeding for genotypes with good adaptation in order to respond to future high temperature.