Variation Changes of Net Photosynthetic Rate of Rice Research Under The Control of Farmland Water Levels

• 1、College of Water Conservancy and Hydropower，Hohai University

Abstract：The diurnal variation law and factors of photosynthetic rate of rice are investigated by the water-level control test of each growth stage of rice in evaporation-infiltration-test-pit. The daily variation of the net photosynthetic rate of the rice leave is affected by the water-level control. The photosynthetic rate of rice leave is reduced under water stress. The net photosynthetic rate of rice leave stricken by drought stress is rapidly recovery and sometime even higher than the normal under the normal water level. But the rice stricken by water logging is still lower than the normal rate. The diurnal variation of photosynthetic rate of rice leave is influenced by the intensity of photosynthetic active radiation and the shape of curve of it is an “M” under the condition of normal water-level and the Intensity of photosynthetic active radiation at noon more than 600μmol•m-2•s-1. But the shapes of curve of the rice whether under water stress or not is same and have a unimodal on the condition of the intensity of photosynthetic active radiation of the day lower than 600μmol•m-2•s-1. The photosynthetic rate of these two kinds of rice has little difference. But the rate of the rice leave under flooding and maintains a certain amount of leakage is faster than them.

Keywords： water level control water stress net photosynthetic rate photosynthetic active radiation rice