后期水分亏缺与增施氮肥对杂交稻叶片光合功能的影响

为了探讨以水肥调控延长水稻结实期叶片功能的可能性，研究了早衰型和非早衰型杂交稻组合后期衰老过程中叶片光合功能对适度水分亏缺和增施氮肥的响应。结果表明，水稻灌浆期水分亏缺促使叶绿素和叶面积衰减加剧，加速Rubisco羧化活性和叶片光合功能衰退，叶片ZR (玉米素核苷)含量下降。对缺水较敏感的中优838、天优998和隆平601其叶绿素衰减率提高了9%~12%；光合速率各下降了19.55%、19.12%、12.73%；ZR含量、Rubisco羧化活性的降幅相对高于其余组合。在限水的同时增施氮肥明显缓解了水分亏缺胁迫的影响，但增氮效果组合间存在较大差异。叶绿素衰减率降低6.14%~27.10%；光合速率，隆平601、天优998、汕优63和中优838提高9.30%~15.81%，两优6326和C两优396提高3%~5%；Rubisco羧化活性，隆平601提高18.94%，中优838提高12.16%，其他组合提高3%~9%；增施氮肥提高了叶片ZR含量，中优838叶片ZR平均含量提高16.05%，C两优396和汕优63分别提高8.31%和8.16%，两优6326和隆平601分别提高4.90%和1.13%。相关分析表明，叶片ZR含量与叶光合速率和Rubisco活性呈极显著正相关，Rubisco羧化活性与光合速率和叶绿素含量极显著相关，叶片总糖含量和稻谷产量与光合速率相关显著和极显著。水稻灌浆期水分不足加速叶片衰老和光合功能衰退，在干旱胁迫时适量增施氮肥，是降低干旱胁迫危害、增强叶片光合功能、延长叶片功能期，防御早衰的有效措施。

Effect of Water Shortage and Increasing Nitrogen Application on Photosynthetic Function of Different Hybrid Rice Combinations at Grain Filling Stage

The response of photosynthetic function of leaves in aging process to water shortage and additional nitrogen application were studied using premature senescence type and non-premature senescence type of hybrid rice combinations. The results showed that chlorophyll content, leaf area, Rubisco activity and photosynthetic rate decreased, and ZR (zeatin riboside) content declined by water deficiency. There were significantly different responses to water shortage among different combinations. Under water stress, Zhongyou 838, Tianyou 998, and Longping 601 were more sensitive than others, and their chlorophyll decline rate increased by 9–12%, whereas photosynthetic rate decreased by 19.55%, 19.12%, and 12.73% respectively, and their ZR content, Rubisco activity dropped much more than those of other combinations, Under water shortage, additional nitrogen application rate could relieve the effect of water shortage stress, the decline rate of chlorophyll decreased by 6.14–27.10%, photosynthetic rate increased by 9.30–15.81% for Longping 601, Tianyou 998, Xianyou 63, and Zhongyou 838, and 3–5% for Liangyou 6326 and C Liangyou 396. And Rubisco activity was enhanced by 18.94% in Longping 601, 12.16% in Zhongyou 838, and 3–9% in other combinations. Additional nitrogen application increased ZR content by 16.05% in Zhongyou 838, 8.31% and 8.16% in C Liangyou 396 and Xianyou 63, and 4.90% and 1.13% in Liangyou 6326 and Longping 601.The correlation analysis showed that ZR content was positively correlated with, photosynthetic rate and Rubisco activity. Rubisco activity and photosynthetic rate had a positive correlation with chlorophyll content, and content of total sugars and yield were significantly correlated with photosynthetic rate.The conclusion was that water shortage speeds up the aging and the decline photosynthetic function decrease. Increasing moderate nitrogen fertilizer will delay the premature senescence of leaves caused by drought stress, enhance the photosynthetic function, and extend photosynthetic function period, suggesting that N nutrition is the most important factor for regulating rice leaf senescence.