中文摘要：

本研究旨在阐明干湿交替灌溉影响水稻产量的生理机制。大田种植3个当地高产水稻品种武运粳24（粳稻）、扬两优6号（两系杂交籼稻）和甬优2640（三系籼/粳杂交粳稻）。自移栽后7 d设置：常规灌溉（CI,保持水层）和干湿交替灌溉（AWD）,观察这2种灌溉模式对水稻根系与地上部生长发育的影响。结果表明,与CI相比,AWD可以显著提高水稻产量与水分利用效率,3个供试品种产量分别提高了5.34%、5.85%和6.62%,水分利用效率分别提高了28.9%、25.3%和27.6%。产量与水分利用效率的提高主要得益于水稻根系和地上部植株的生理功能的改善,表现出灌浆期较高的根系氧化力、根系伤流液强度、根系与叶片中玉米素与玉米素核苷的含量、剑叶净光合速率、籽粒中较高的蔗糖合酶、腺苷二磷酸葡萄糖焦磷酸化酶和淀粉合酶活性、较大的深层（10-20 cm）根系、较高的分蘖成穗率与叶面积指数。

英文摘要：

Alternate wetting and drying（AWD） irrigation has been widely adopted to replace conventional irrigation（CI） for saving water and increasing water use efficiency（WUE） in irrigated rice systems in China. However, there is limited information about how AWD affects yield, WUE, and root and shoot growth and development. To fill this knowledge gap, we conducted the experiment using three local high-yielding rice cultivars, Wuyunjing 24（japonica）, Yangliangyou 6（two-line indica hybrid rice）, and Yongyou 2640（three-line indica/japonica hybrid rice） under the two water managements, CI and AWD, during the whole growing season. The results showed that, when compared with CI, AWD increased grain yield by 5.34%, 5.85%, and 6.62% and WUE by 28.9%, 25.3%, and 27.6%, respectively which mainly attributed to greater root oxidation activity, amount of root bleeding sap, content of cytokinins（zeatin ＋ zeatin riboside） in roots and leaves, highten photosynthetic rate of flag leaf, deeper root distribution, increased productive tillers and leaf area, and enhanced activities of enzymes involved in sucrose-to-starch conversion in grains during grain filling. The results demonstrate that AWD is an effective practice to increase grain yield and water use efficiency through enhancing root and shoot growth and development.