Genetic Variation For Heat Tolerance In Primitive Cultivated Subspecies Of Triticum Turgidum L.

High temperature (heat) stress is a major constraint for the productivity of crops worldwide. Wheat (Triticum spp.) is particularly vulnerable to high temperature stress compared to other crops. The principal way to mitigate heat damage is to develop heat-tolerant varieties by identifying heat-tolerant germplasm and employing the tolerant lines in breeding programs. The objectives of this study were to investigate the genetic variation for heat tolerance in primitive cultivated subspecies of tetraploid wheat Triticum turgidum L. (AABB genome) and to identify heat-tolerant genotypes. Thirty-eight tetraploid wheat accessions belonging to five subspecies collected from 19 countries were studied for heat tolerance in day/night temperatures of 36/30 degrees C beginning at anthesis. Several lines were classified as heat-tolerant based on small reductions in seed number, single-kernel weight, and total grain weight, as well as slow chlorophyll degradation under heat stress. T. turgidum subsp. polonicum IG110572 from Algeria, T. turgidum subsp. dicoccum IG45067 from Oman, and T. turgidum subsp. dicoccum IG45393 from Eritrea had responses similar to the reference heat-tolerant hexaploid wheat, 'Kauz'. These heat-tolerant accessions may be useful to breeding programs for the improvement of heat tolerance in tetraploid or hexaploid wheat.