Experiment And Mathematical Model Of Rice Photosynthesis Under Controlled Irrigation

Rice net photosynthesis rate under controlled irrigation is disscussed in comparison with shallow water irrigation (CK) as well as leaf photosynthetic characteristics, CO2 daily assimilation in this dissertation. The relativity are analyzed between Par, temperature, relative humidity, CO2 concentration in the air and rice net photosynthesis rate separately considering the influence of environment to rice photosynthesis. Specially the influence of soil moisture to rice photosynthesis is researched. Rice photosynthesis rate is simulated and validated by using photosynthetic models on the basis of a great lot of experimental datum. The influence of stomatal conductance to photosynthesis rate is researched primarily. Water use efficiency (WUE) of rice under two irrigation styles in shining day and all growth seasons are computed and compared. The main conclusions are the followings:1.The photosynthesis rate curves of rice under the controlled irrigation are almost the same as those under CK in shining day and photosynthesis rate peak value of rice under controlled irrigation are always in advantage almost all the time but the peak value appears in different time.2.The photosynthetic characteristics of rice under controlled irrigation at tellering , ear sprouting and florescence , heading , milk and mature stage are almost better than those under CK.3.The CO2 daily assimilation of unit area of rice under two irrigation styles are almost equal and does not show marked difference in the main growth seasons though that of the rice under controlled irrigation shows a little better. The change of the CO2 daily assimilation has the very comparability in the whole growth seasons.4.The soil moisture in all the growth seasons fits for the photosynthesis physiological want of rice, and the photosynthesis rate seldom decreases near the soil moisture low level.5.The Saeki-Monsi photosynthetic model has a good stimulating precision. After the model have been modified by adding soil moisture function, the results is better than the previous ones. The precision and applicability are also improved. Using the new model, the most fitting soil moisture for the rice photosynthesis is gained.6. The rice has the maximum photosynthesis rate (Pmax)and light quanta efficiency (a ) under controlled irrigation and CK at ear sprouting and florescence , heading stage. Pmax and a of rice under controlled irrigation are higher than those under CK at the most time.7. The difference of water use efficiency (WUE) of rice under two irrigation styles in general are not marked. The WUE of rice under controlled irrigation are higher than that under CK in all the growth seasons except at tellering stage.