水分胁迫条件下不同形态氮素营养对水稻叶片光合效率的调控机理研究

The Regulatory Mechanism of Different Nitrogen Form on Photosynthetic Efficiency of Rice Plants Under Water Stress

【目的】研究不同形态氮素和水分胁迫耦合作用下水稻的光合生理特性。【方法】采用营养液培养及聚乙二醇(PEG,6000)模拟水分胁迫的方法,研究不同形态氮素营养和水分胁迫耦合作用下水稻叶片光合特性及1,5-二磷酸核酮糖羧化酶(Rubisco)含量的变化规律,分析羧化效率(CE)、全氮含量、可溶性蛋白与Rubisco含量之间的关系。【结果】在水分胁迫条件下,NH4+-N营养水稻新完全展开叶中Rubisco含量与非水分胁迫下的相比显著增加,单位Rubisco活性(CE/Rubisco含量)与非水分胁迫条件下相应供氮形态处理相比下降了13.3%;而NO3--N营养水稻的Rubisco含量则明显降低,单位Rubisco活性下降了23.0%。因此,水分胁迫对NH4+-N营养水稻单位Rubisco活性的抑制作用小于供NO3--N营养水稻;其次,水分胁迫提高了NH4+-N营养水稻新完全展开叶的全氮含量,而对NO3--N营养水稻则无明显影响;此外,水分胁迫虽然也明显增加了3种形态氮素营养条件下水稻新完全展开叶中可溶性蛋白的含量,但其对NH4+-N营养水稻的Rubisco含量占可溶性蛋白的比例无显著影响,而对NO3--N营养水稻则有显著的降低效应。【结论】水分胁迫对供NH4+-N营养水稻光合效率的抑制效应小于供NO3--N营养水稻。

[Objective] The effects of different nitrogen forms and water stress on the characteristics of photosynthetic physiology of rice plants were studied. [Method] A hydroponic experiment with simulated water stress by PEG （6000） was conducted. The photosynthetic characters and Rubisco content and activity were studied by analyzing carboxylation efficiency （CE）, total nitrogen content, soluble protein content and Rubisco content in newly expanded leaf of rice plants. [Result] The results showed that, under ammonium nutrition, there was no significant difference in CE of rice plant between water stress and non-water stress. Rubisco activity, however, was reduced 13.3% by water stress. Under nitrate nutrition, both of CE and Rubisco content reduced under water stress, and Rubisco activity reduced 23.0%. Thus, the inhibitory effect on Rubisco activity （CE/Rubisco） of rice plants supplied with ammonium was lower than that of supplied with nitrate. Furthermore, water stress also increased total nitrogen content in newly expanded leaf of rice plants supplied with ammonium, while it had no effect under nitrate supply. Water stress increased soluble protein content in newly expanded leaf supplied with three nitrogen forms, although there was no significant effect on the ratio of Rubisco content to soluble protein under ammonium supply. The ratio decreased under nitrate supply. [ Conclusion ] The inhibitory effect of water stress on photosynthetic efficiency of rice plants supplied with ammonium was lower than that of plants supplied with nitrate.