中文摘要：

采用水培试验方法,研究了供氮水平对苗期大豆生长和根系吸水特性的影响。结果表明,同一阶段,营养液氮素浓度为2 mmol·L-1的处理,大豆地上部干物重和根干重均为最大,供氮水平对根干重的影响小于对地上部干重的影响;播种后30 d内,供氮水平对单株大豆日平均根系吸水速率的影响较小,30 d后大豆日平均根系吸水速率随营养液氮素浓度的升高呈现出先增大后平稳的趋势;最优水分条件下,单位根长潜在吸水系数并非一个常数,它受供氮水平和生长阶段的影响。

英文摘要：

A nutrient solution experiment was conducted to investigate the effect of different levels of nitrogen supply on growth and root water uptake characteristics of soybean seedlings.The results showed that at the same growth period ,both the root dry weight and shoot dry weight were highest when nitrogen concentration was 2 mmol· L-1.Nitrogen concentration had less effect on root dry weight than on shoot dry weight.Within 30 DAS ( DAS: days after sowing ) , daily average root-water-uptake rates per plant were insignificant among different nitrogen supply levels.After 30 DAS, daily average root-water-uptake rates per plant increased gradually with increasing nitro-gen level but changed slightly when nitrogen concentration was over 2 mmol· L-1.Under optimal water condition , potential root-water-uptake per unit root length was not a constant , which was affected by nitrogen supply levels and growth periods.