WATER USE AND MOISTURE STRESS EFFECTS
AT DIFFERENT GROWTH STAGES
Water use and moisture stress effects vary at different growth stages of rice.
Sufficient moisture supply is more critical in some growth stages than others.
Moisture stress reduces crop yield most when it occurs during the critical growth
stages.
Water Use
It is generally believed that cereal crops show a marked sensitivity to moisture
stress during the formation of the reproductive organs and during flowering. By
and large, cereal crops can withstand and recover from mild or relatively brief
periods of moisture stress if favorable conditions are quickly reestablished. With
more severe stress, the preflowering stage is the least sensitive and the anthesis
and spikelet-filling stages are the most sensitive. Matsushima (1962) reported
that rice is most sensitive to moisture stress from 20 days before heading to 10
days after heading. Van de Goor (1950) had earlier reported that flooded rice
used the maximum amount of water at that time. That suggests that the critical
period for moisture stress coincides with the period in which plants use the most
water.
Seasonal water requirement differs with different growth stages. For water
management practices of rice, the growth stages of rice can be divided as the
seedling, vegetative growth, reproductive, and ripening stages. In areas with low
rainfall or a highly variable rainfall pattern, irrigation practices should be
developed to assure needed water at the critical growth stages.