Abstract: The effect of irrigation modes on the senescence of hybrid rice and some physiological activity was studied in the experiment. The results showed that irrigation modes affected obviously the senescence of hybrid rice. By cutting off the water supply at different stages after flowering, plant was subjected to water stress, and the decrease rate of the physiological activity speeded up, then the rate for the accumulation of dry weight in grain slowed down and seed setting percentage reduced, as a result, the output reduced. The earlier stare the water supply was cut off at, the more serious the yield reduced. However, intermittent irrigation, because of delaying the senescence of root, increasing photosynthetic rate, prolonging the duration of the accumulation of dry weight in grain, enhancing seed setting, and raising efficiency of increase production, consequently, the yield respectively increased by 7.4% and 17.7-28.3% compared with long term irrigation and cutting off the water supply earlier than expected. It is possible that irrigation modes control the senescence of the aerial parts by means of promoting the synthesis of some amino acids and restraining the synthesis of other amino acids in roots.

Key words: Hybrid rice, Irrigation mode, Senescence, Amino acid

摘要： 对长灌水、间歇灌和早断水等灌水方式对杂交水稻衰老和生育后期一些生理活性的影响进行了研究，以期有助于杂交水稻衰老的谢节及最佳灌水方案的建立。结果表明，灌水方式明显影响杂交水稻的衰老，早断水使植株开花后不同时期遭受水分胁迫，不同程度上加速植株生理机能的衰退，使籽粒干物质积累受阻，结实率下降而减产。断水的时间越早，减产越严重而间隙灌溉由于延缓根系衰老，增强叶片光合能力，延长灌浆时间，提高了结实率，从而提高增产效率，其最终产量比长灌水和早断水分别增7．4％ 和13．7～28．3％ 不同供水状况可能通过对根系中某些氨基酸合成的促进和另一些氨基酸合成的抑制而对上部的衰老进行调节。

关键词: 杂交水稻, 灌水方式, 衰老, 氨基酸, 生理特征