极端干旱区滴灌量对冬小麦水氮利用及根系分布的影响

为明确新疆南部极端干旱区滴灌小麦的灌水量阈值，在常规沟灌(总灌量为3 750 m·hm^-2)的基础上，设计了四种减量滴灌模式(灌水量分别为3 376、3 000、2 625和2 250 m·hm^-2)，分析了滴灌量对冬小麦产量、水氮利用效率及根系分布的影响。结果表明，土壤无机氮残留量因灌水量不同而异，灌水3 376和2 625 m·hm^-2时较低；各灌水条件下土壤无机氮残留量均随小麦生育期推进先降后升，在灌浆期达到最高，而后下降。随土层深度的增加，土壤中无机氮含量也逐渐递减。冬小麦水分利用效率随灌水量的增加呈先增后降趋势，灌水量在2 250 ~3 000 m·hm^-2范围内，随灌水量的增加，水分利用效率先逐步增加，而后下降。小麦根系长度随灌水量的减少呈递减趋势，当灌水量高于或低于3 000 m·hm^-2时，小麦根系出现早衰现象。

Effect of Drip Irrigation Amount on Water and Nitrogen Usage and Root System Distribution of Winter Wheat under Drought Condition

In order to determine the threshold of water supply for winter wheat with drip irrigation and to provide a scientific basis for production, different irrigation experiments were carried out in the extremely arid areas in Southern Xinjiang. In this study, 4 decreasd drip irrigation treatments were conducted as experiment groups (total water volume of growth stage were 3 376, 3 000, 2 625 and 2 250 m·hm^-2), compared with normal furrow irrigation (total water volume of growth stage was 3 750 m·hm^-2). This research investigated the yield, water and nitrogen efficiency, and root distribution of different treatments. The result indicated that with the succession of the growing stages, inorganic nitrogen residues in soil showed increased firstly, then decreased, reaching a peak at the filling stage, and then decreased secondly. The inorganic nitrogen showed decreasing trend with the increase of soil depth. Along with the increase of irrigation volume, water use efficiency increased firstly, and then decreased, reaching a peak at 3 000 m·hm^-2. Root length reduced with the decrease of total irrigation volume. The root showed distinctively earlier senescence when the irrigation volume was higher or lower than 3 000 m·hm^-2.