Flowering and pollination appear to be the most sensitive periods. Several studies have been conducted with spring wheat and winter wheat to evaluate limited irrigations on the crop. Stress was most critical during and after heading. This response is similar to that for barley. There is little or no measurable benefit from irrigating spring grains before the boot stage, unless moisture stress is evident.
Stress is likely to occur when the plants appear wilted and the leaves curl.
The period between grain filling and maturity is critical. Yield is reduced most when stress starts during soft dough or during or following heading. Stress during maturing results in about a 10 percent lower yield. Moderate stress during the early vegetative period has essentially no effect on yield. Drought stress on winter wheat production during early spring regrowth results in heading about seven to 10 days prematurely, a shortened growth period and thus reduced yield.