Performance of Yield and Stability of Wheat Genotypes under High Stress Environments of the Central Region of Saudi Arabia

The current study aimed at assessing the heat tolerance of twelve wheat genotypes under four environmental conditions (two sowing dates and two years). Wheat genotypes were sown at two dates: December (favorable) and January (heat stress) during winter seasons of 2005/2006 and 2006/2007. The combined analysis of variance showed that plant height, spike length, number of kernels per spike, harvest index and grain yield were significantly influenced by years, sowing dates, and genotypes. The results showed that sowing at the first date increased plant height, grain yield, and harvest index. Highly significant genotype differences were recorded for all characters. In general, genotypes (YR-19 and YR-20) produced the highest grain yield in both seasons, while, local cultivar Sama produced the lowest grain yield. Regarding the interaction effect between sowing dates and wheat genotypes on grain yield, YR-20 produced the highest grain yield under the first sowing date. The stability analysis revealed that genotypes YR-19 and YR-20 showed high and stable yielding. On the other hand, YR-2 and YR-3 showed below-average stability (b = 1.582 1.594). Also, the genotypes YR-20 and YR-19 were relatively heat resistant (HSI values 1), while local cultivar Sama and YR-2 were relatively heat susceptible (HSI 1).