Selective uptake of nitrogen by Suaeda salsa under drought and salt stresses and nitrogen fertilization using 15N

Plant nitrogen uptake can be influenced by drought and salt stresses and nitrogen fertilization; however, the selective uptake of different forms of nitrogen is poorly understood. We conducted a short-term N-15-labeling experiment to investigate the preferences of Suaeda salsa for nitrate, ammonium and amino acid. Our results indicated that nitrate and glycine, especially nitrate, were major nitrogen sources and glycine was absorbed after decompostion. Drought and salt stresses had no significant effect on the uptake of ammonium (p > 0.05). However, nitrate uptake was strongly related to water content and nitrogen application (p < 0.05) instead of salinity (p>0.05). Drought and nitrogen application reduced the uptake of nitrate by almost 65.73% and 90.29%, respectively, suggesting appropriate soil water content and nitrogen deficiency could promote nitrate uptake. The uptake of glycine was mainly influenced by water content, and drought stress decreased glycine uptake by almost 89.74%. (C) 2017 Elsevier B.V. All rights reserved.