Abstract: To investigate the effects of water and nitrogen application on water consumption and water use efficiency in soybean (Glycine max) intercropped with woad (Isatis indigotica) in the cool-temperate irrigation area of Hexi, the following treatments were established: pure woad (M1), pure soybean (M2), woad : soybean 2:1 (M3), woad : soybean 1:1 (M4), two nitrogen fertilizer gradients—low nitrogen (N1) 200 kg·hm–2 and high nitrogen (N2) 250 kg·hm–2, and two water stress gradients—severe water deficit (W1) and mild water deficit (W2). The effects of cropping patterns and water-nitrogen coupling on crop water consumption, yield, and water use efficiency were analyzed. Results indicate that throughout the crop growth period, crop water consumption increased with higher irrigation and nitrogen application rates, following the pattern W1N1 < W2N2. Under identical nitrogen application conditions, woad-soybean yield significantly increased with higher irrigation rates, while water use efficiency decreased with increased irrigation. Across all treatments, under mild water deficit, the yield of woad-soybean intercropping outperformed monocropping. Within intercropping systems, woad yielded higher, with the W2N1M3 treatment achieving the highest yield of 7500.91 kg·hm–2. Under identical nitrogen application conditions (N2 treatment), the W1 treatment exhibited significantly higher water use efficiency than the high-water W2 treatment. At the W1 level, both woad and soybean yields increased by 20.06% and 17.39%, respectively, compared to W2. This indicates that water-nitrogen coupling exerts significant interactive effects on water use efficiency and yield in woad-soybean intercropping. Simultaneous cropping enhances crop water use efficiency. Therefore, implementing mild water deficit combined with low nitrogen application in woad-soybean intercropping represents an optimal water-saving and high-yield model for woad cultivation in the cold-cool irrigation areas of Hexi corridor.

Key words: water-nitrogen coupling, intercropping, water consumption characteristics, yield, water use efficiency

摘要： 为探索水氮施用对河西冷凉灌区菘蓝Isatis indigotica间作大豆Glycine max耗水量及水分利用效率的影响规律，设单作菘蓝(M1)、单作大豆(M2)、菘蓝‖大豆2:1 (M3)、菘蓝‖大豆1:1 (M4)，两个氮肥梯度低氮(N1) 200 kg·hm–2、高氮(N2) 250 kg·hm–2，两个水分梯度重度亏水(W1)、轻度亏水(W2)处理，分析种植模式及水氮耦合对作物耗水量、产量及水分利用效率的影响。结果表明，在作物全生育期中，随着灌水与施氮量增加，作物耗水量呈增加趋势，表现为W1N1＜W2N2。在相同施氮条件下，菘蓝大豆产量随着灌水量的增加显著增加，而水分利用效率却随着灌水量的增加而降低。在所有处理中，轻度亏水下菘蓝大豆间作的产量优于单作，同时间作模式下菘蓝产量更高，W2N1M3处理的菘蓝产量最高，为7500.91 kg·hm–2。在相同施氮条件下(N2处理)，W1处理水分利用效率显著高于高水W2处理，菘蓝大豆在W1水平下较W2分别提高20.06%和17.39%。由此表明，水氮耦合对菘蓝大豆间作水分利用及产量具有显著互作效应，同时间作有利于提高作物水分利用效率。因此菘蓝大豆间作采用轻度亏水结合低氮处理是河西冷凉灌区种植菘蓝较佳的节水高产模式。

关键词: 水氮耦合, 间作, 耗水特征, 产量, 水分利用效率