中文摘要：

以夏玉米为材料,设4个灌水水平：337.5、6751、012.5、1 350 m^3/hm^2;4个施氮水平：75、150、225、300 kg N/hm^2,研究限量灌溉和施氮对夏玉米苗期生长及生理指标的影响。结果表明：严重干旱会抑制玉米的生长。在玉米苗期,充分供水和高氮对玉米的生长不利,轻度亏缺与中氮组合使玉米苗期处于最佳生长状态,水氮共同作用对玉米的光合速率有促进作用;玉米苗期适度经受水分亏缺,有利于根系的生长;在同一施氮水平下,不同程度水分亏缺处理的根冠比（R/S）大于充分供水的处理。玉米苗期叶水势随灌水量的增大而增大,在灌水量相同时,叶水势随施氮量的增加而逐渐变大;干旱会使玉米光合速率下降,但适量增施氮肥可增加玉米的光合速率。

英文摘要：

The effects of limited irrigation and nitrogen fertilization on the growth and development and physiological characteristics of maize were tested.Take summer maize as the experimental material,water was supplied by four levels： 337.5,675,1 012.5 and 1 350 m^3/hm^2;and nitrogen also by four levels： 75,150,225,300 kgN/hm^2.The result showed that serious water stress restrains maize growth.During maize seedling,sufficient water and high nitrogen make against growth of maize crop.However,mild water stress and moderate nitrogen made an optimum growth state of maize,and water and nitrogen can enhance photosynthesis rate of maize;During maize seedling,water stress is advantage of root growth,under the same nitrogen level,the root shoot ratio（R/S） of different water stress is bigger than that of sufficient water.The leaf water potential increases with the increase of irrigation water amount.Under the same irrigation water amount,with the increase of nitrogen fertilization,leaf water potential of maize during seeding is increased.While under drought condition,the photosynthesis rate is decreased,and increasing of nitrogen can increase the photosynthesis rate.