| To reveal influence of dripping water amount on the ultra-high-yielding soybean root growth，a field research method was employed. Treatments with four dripping levels at 975 m3·hm-2(W1), 1 575 m3·hm-2 (W2), 2 175 m3·hm-2 (W3), and 2 775 m3·hm-2 (W4) were set to examine the influences on moisture in 0～100 cm soil layer, soybean root dry weight, lateral root length and yield. The results showed that with the increase of water dripping amount, soil moisture in 0～40 cm was increased. Soil root dry weight density and lateral root length density in 0～20 cm had been increased most, followed by those in 20～40 cm soil layer. At late growth stage, total root dry weight and total lateral root length in 0～80 cm soil were increased significantly. At the beginning of filling period, compared to those with W1 treatment, root dry weight with W2, W3, and W4, were increased by 14.2%, 30.4%, and 41.1%, respectively. Additionally, lateral root lengths became increased by 17.4%, 25.7%, and 40.3%, respectively. Root activity in 0～40 cm soil was increased significantly, as well as root bleeding sap, resulting in improvement of water use efficiency. Moreover, with W3 and W4 treatments at the beginning of filling period, soil root dry weights in 0～80 cm were 88.6 g·m-2 and 95.8 g·m-2, respectively; lateral root lengths were 432.4～482.9 m·m-2; yields were 6 082.6 kg·hm-2 and 6404.7 kg·hm-2, respectively; and water use efficiency was about 1.30. In conclusion, suitable drip amounts for soybean in Xinjiang Yining were 2 175～2 775 m3·hm-2. |