Water deficit on the growth and yield of irrigated soybean in the Brazilian Cerrado region

ABSTRACT The increase in disputes over water use in the Brazilian Cerrado has demanded improvements in irrigation management and increase in water use productivity. In this context, deficit irrigation is an interesting management strategy, as it enables water savings without significant losses of yield. The present study aimed to evaluate the phenology and yield of a soybean cultivar subjected to different soil moisture contents. The experimental design used was randomized blocks with five treatments and four replicates. In each treatment, an irrigation strategy was applied based on the available water in the soil (AW). The T1 treatment was performed by applying from 80 to 100% AW; in T2 treatment, the allowed variation was from 60 to 80% AW; in T3 treatment, it was from 40 to 60% AW; in T4, from 20 to 40% AW; and in T5, from 0 to 20% AW. It was verified that, in winter and summer, even without the need to reduce water withdrawal, it is recommended to apply from 60 to 80% of the available water in the soil for soybean crop, without decreasing yield. In situations of water restriction, it is possible to have yield of around 55 and 70% in winter and summer, respectively, for the condition from 20 to 40% of the available water in the soil.

摘要 巴西塞拉多（Brazilian Cerrado）地区用水纠纷的增多，对灌溉管理优化与用水生产效率提升提出了更高要求。在此背景下，亏缺灌溉（Deficit Irrigation）作为一种颇具应用前景的管理策略，可在实现节水的同时避免产量出现显著损失。本研究旨在评估不同土壤含水量条件下某大豆品种的物候表现与产量水平。本试验采用随机区组设计，设置5个处理、4次重复，各处理均基于土壤有效含水量（Available Water, AW）制定灌溉方案：T1处理施加80%~100%的土壤有效含水量；T2处理允许的含水量波动范围为60%~80%AW；T3处理为40%~60%AW；T4处理为20%~40%AW；T5处理为0%~20%AW。研究结果证实，无论冬季还是夏季，即便无需缩减取水总量，大豆灌溉采用60%~80%的土壤有效含水量即可保证产量不受损失。在水分受限的场景下，当土壤有效含水量维持在20%~40%区间时，大豆冬季与夏季的产量分别可达到常规水平的约55%与70%。