Effects of salt stress and nitrogen application on growth and ion accumulation of Suaeda salsa plants

Suaeda salsa is a typical pioneer species which can grow well in high salt environmental conditions. The objective of this study is to evaluate the effect of different levels of salinity (5.25, 10.5 and 21g NaCl per kg soil) and nutrient supply (0, 0.3, 0.6 and 1.2g urea per kg soil) on plant morphology, biomass, accumulation of ions and C/N ratio in leaves of S. salsa. The results showed that the plant height, number of branches, length of branches and diameter of shoot were significantly affected by salt stress, and the nitrogen released the negative effects of salt. The nitrogen treatment increased the biomass of leaf, shoot and root. Leaf water content was significantly affected by the interaction of salt stress and nitrogen treatment. The content of Na⁺ and Cl^- increased significantly as increasing of salt, the content of K⁺, Ca²⁺, Mg²⁺ and SO₄^2- decreased simultaneously to keep ion balance. The C/N ratio decreased significantly as increasing of nitrogen treatment. The content of proline increased significantly with the increasing of salt and nitrogen treatments. The results together indicated that at different salt environment, different amount of nitrogen supply can be used to improve the population growth of S. salsa plants, and the restoration of degraded wetland could be accelerated by nutrient supply reasonably.