From University of Wisconsin-Extension:
What Happens Within The Corn Plant When Drought Occurs?
...Yield is reduced when evapotranspiration demand exceeds water supply from the soil at any time during the corn life cycle. Nutrient availability, uptake and transport are impaired without sufficient water. Plants weakened by stress are more susceptible to disease and insect damage. Corn responds to water stress by leaf rolling. Highly stressed plants will begin leaf rolling early in the day. Evapotranspiration demand of corn varies during its life cycle (Table 1). Evapotranspiration peaks around canopy closure. Estimates of peak evapotranspiration in corn range between 0.20 and 0.39 inches per day. Corn yield is most sensitive to water stress during flowering and pollination, followed by grainfilling, and finally vegetative growth stages.Table 1. Estimated corn evapotranspiration and yield loss per stress day during various stages of growth.
|Growth stage||Evapotranspiration||Percent yield loss per day of stress (min-ave-max)|
|inches per day||%|
|Seedling to 4 leaf||0.06||---|
|4 leaf to 8 leaf||0.10||---|
|8 leaf to 12 leaf||0.18||---|
|12 leaf to 16 leaf||0.21||2.1 - 3.0 - 3.7|
|16 leaf to tasseling||0.33||2.5 - 3.2 - 4.0|
|Pollination (R1)||0.33||3.0 - 6.8 - 8.0|
|Blister (R2)||0.33||3.0 - 4.2 - 6.0|
|Milk (R3)||0.26||3.0 - 4.2 - 5.8|
|Dough (R4)||0.26||3.0 - 4.0 - 5.0|
|Dent (R5)||0.26||2.5 - 3.0 - 4.0|
derived from Rhoads and Bennett (1990) and Shaw (1988)