Research On Compensation Effect Of Rice Under Water Stress

Pot and test-pit experiments were conducted to study the compensation effect of rice under water stress. The results indicated that the compensation effect of rice on development, growth, physiological and ecological characteristics, accumulation of dry matter ,yield and water use efficiency(WUE) were likely to appear during or after water stress period. Degree of compensation effects depends on srress severity, growth stage and duration of stress. The main results were as following:1. The development and growth of rice were depressed by water stress, some indexes such as the height of plant, number of tiller and leaf, leaf area and leaf area index were restricted. The effect of inhibition has some hysteresis and was enhenced with the increasing degree and stress duration. After rewatering, the height of plant, number of tiller and leaf, leaf area and leaf area index of the stressed treatments accelerated, then approached or exceeded those of CK and showed obvious compensation effect.2. Pot experiment indicated that photosynthesis of rice leaf was depressed. The effect of photosynthesis inhibition became more obvious with the increasing degree and longer stress duration. Rewatering after drought improved photosynthesis of the stressed treatments and performed compensation effect. Hysteresis of water stress greatly affected transpiration rate (Tr) and stomatal conductance (Cs) of the rice leaf. Stomatal factor was a very important factor to affect photosynthesis. The chlorophyll content could be greatly improved by water stress of different stages and decreased after rewatering. The malondialdehyde (MDA) content of rice leaf increased because of water stress in tillering stage and rewatering could release the bad effect. Water stress of different stages could decrease root activity. Root activity of stressed treatments greatly exceeded CK after rewatering and obviously performed compensation effect.3. Water stress of different degree and duration could reduce accumulation of dry matter and biomass yield. Rewatering had compensation effect in the compensative growth and accumulation of root and shoot, stimulated partition and transportation of dry matter equitably in order to high yield.4. Water stress of different stage could improve WUE of rice in leaf lever and yield lever. Water stress adjusted Stomatal behaviour to reduce water consumption of rice in the whole growth stage, so WUE of rice was greatly improved.