Abstract: To clarify the factors determining the diurnal courses of photosynthesis in a day, photosynthetic rate(P_n), photosynthetic photon flux(PPF), stomatal conductance(S_c), intercellular CO₂ concentration(C_i), relative humidity(RH), temperature(T), transpiration(Trans), initial Rubisco activity(RI), total Rubisco activity(RT),Rubisco activase activity(RCA) were measured. The maximal photosynthetic rate occurred at about 8:30 a.m. when initial Rubisco activity reached the maximum. Then both of them gradually decreased down. After 13:00 p.m., they rose up positively correlated with P_n and the regression coefficient between them was 0.9368. By the correlation analysis and path analysis, stomatal conductance and initial Rubisco activity were found to be major factors limiting photosynthetic rate. The interaction of Rubisco activase activity and other factors on photosynthetic rate were studied by using response surface, and the response surface of every mathematical model was drawn to express their intrinsic relationship. The study showed that Rubisco activase activity had an effect on photosynthetic rate by its regulating initial Rubisco activity.

Key words: photosynthesis, enzyme activity, environmental factor, correlationship, factor analysis, rice

摘要： 研究了水稻光合日变化中Rubisco活化酶活力、Rubisco初始活力、光强、相对湿度、气孔导度、蒸腾速率、胞间CO2浓度、温度等因素的作用。Rubisco活力的动态变化研究结果表明，Rubisco初始活力是双峰曲线，其参与光合日变化过程，存在着明显的“午休”现象。Rubisco初始活力和气孔导度是影响光合速率的重要生理和生化因子，而光强是影响光合速率的重要生态因子。Rubisco活化酶活力对光合速率的直接影响较小，其本质是调节Rubisco初始活力。

关键词: 光合作用, 酶活性, 环境因子, 相关关系, 因子分析, 水稻