This subset contains Triticum aestivum materials selected by Dr. Yann Manes, formerly a CIMMYT dryland bread wheat breeder, for tolerance to drought.

A drought stressed crop rapidly loses potential yield. When a young crop has too little water its first response is to conserve what water there is by closing its stomata. Without carbon dioxide photosynthesis stops and so the sugars it normally makes from the carbon are no longer available for growth. So growth stops. If moisture remains limiting, the crop eventually runs out of time to produce leaves, tillers and spikes and the consequence is a thin canopy with few small spikes, few grains and low yield. If moisture stress occurs after anthesis the grains are affected, as they are now the growing part of the crop. The consequence of post-anthesis stress (milk stage) is that grains are pinched, shriveled and small.