Water Requirement Rules And Water Use Efficiency Of Rice Under Different Water Treatments

The experiment was carried out in the farm of Chahayang from 2006.5 to 2007.10, to study water requirement characteristic of rice, physiology process, yield formation and water use efficiency under different irrigation treatments. By taking different extent water deficit in each period of rice, the characteristics and rules of water demand for rice in cold area were found; and yield of rice in different water treatments was obtained. Following primary results were obtained:Earing stage is the largest water requirement rate in all stages, and it is most sensitive to water deficit, jointing-booting stage is second, tillering stage and filling stage are not so sensitive to water deficit.By taking different extent water deficit in each growing period of rice, the effects on growth, development and yield of rice are different from each other. The greatest effects on yield of rice by the same extent water deficit is jointing-booting stage, earing stage is second; It's found that taking proper extent water deficit in tillering stage of rice don't make great effect on yield, and taking some extent water deficit in filling stage of rice don't make great effect on yield while it will be more better than control treatment in some indexes,such as spike length, ear length, plant height, and 1000-grain weight.Different soil moisture conditions are closed with water requirement and yield of rice, the effects on growth and development of rice is not the same by different water deficit in different growing period. It's primarily presented that the water deficit would significantly decrease water demand of rice, the greatest effect period is jointing-booting stage, earing stage is second; But it doesn't have the same effects on yield of rice. It's found that proper extent water deficit in tillering and filling stage would beneficial to coordination and development of rice, and it doesn't have great effect on rice yield.It's found that leaf photosynthesis rate and transpiration rate are nonlinear relation, photosynthesis rate and stomatal conductance are nonlinear relation by correlation analysis of physiological factors. This study holds that it's feasible that not only decrease water consumption but promote increasing output of photosynthesis by taking some measures to increase stomatal resistance.The effects on water use efficiency of rice are different from each other by taking different extent water deficit in each growing period of rice. The general relation of leaf water use efficiency in testing time is: light drought>control treatment>heavy drought, the water use efficiency of former period of continuous middle drought treatment is slightly higher than control treatment, while the water use efficiency of later period of continuous middle drought treatment is less than control treatment. The water use efficiency of treatment (1) (2) (10) and (11) was higher than treatment (12) of control treatment. The water use efficiency of treatment (6) was the lowest, and the treatment(8)was much lower. The water use efficiency of other treatments is lower than control treatment in some extent, but it has no large difference. Through comparing with every experiment result, heavy and long time drought will make leaf water use efficiency of rice decrease, and taken some proper measures will beneficial to obtain more higher water use efficiency.