遮光对杂交水稻组合生育后期光合特性和产量的影响

对6个光敏感性不同的杂交稻组合在遮光处理条件下的光合特性及其对逆境的适应机理进行了研究。结果表明，在田间通过抽穗期遮光处理(80%遮光率) 15 d，及恢复自然光照15 d后，水稻的产量显著降低；水稻剑叶叶绿素含量增加，恢复生长15 d后，并未恢复到正常水平；弱光降低功能叶片的净光合速率，减少光合产物向籽粒的运输，增加MDA含量和叶面积指数，而SOD活性变化不一。杂交水稻适应弱光环境的能力是由自身因素决定的，组合之间存在很大差异。弱光胁迫下剑叶能保持较高的净光合速率、量子效率、叶绿素含量以及较低的MDA含量、SOD活性，是耐弱光水稻品种的生理基础。

Effect of Shading on the Photosynthetic Characteristics and Yield at Later Growth Stage of Hybrid Rice Combination

Photosynthetic characteristics in shading treatment and adaptation mechanism under adverse conditions were studied using in six hybrid rice combinations with different photosensitivity. The results showed that the grain yield was significantly reduced under shading treatment (80% shading rate) at heading stage, then recovered to natural illumination; the chlorophyll (a+b) and chlorophyll b contents were increased, but failed to reach the normal level after the recovery period; low light reduced the photosynthetic rate of the functional leaves and the quantity of photosynthetic products transported to grain, meanwhile, the content of malondialdehyde (MDA) and leaf area index were increased, the activity of SOD varied differently. There was a great difference in adaptability to low light environment among combinations. It is the physiological basis of rice tolerance to shading that the flag leaf under low light stress can maintain a higher net photosynthetic rate (P_n), quantum efficiency, chlorophyll content, and lower content of malondialdehyde (MDA) and lower SOD activity.