Wheat requires cool temperatures, particular during it's vegetative phases, for proper development. Large areas of wheat are grown under warmer or hotter than optimal temperatures causing significant yield reductions.

Exposure of wheat to warm and hot conditions may be due early or late sowing, cultivation in sub-optimal environments, or climate change. This subset identifies bread wheat (Triticum aestivum) materials that are tolerant to heat.

Source: CIMMYT Wheat Germplasm Bank