Effects of Different Sodium Salt Stress on Seed Germination and Seedling Growth of Robinia pseudoacacia

In order to investigate the effects of different sodium salts on seed germination and seedling growth of Robinia pseudoacacia seeds, different concentrations of medium salts were used in this experiment(NaCl and Na₂SO₄, alkaline salt（Na₂CO₃） and mixed salt（NaCl+Na₂CO₃） were used to treat seeds, and the effects of different sodium salt stress on seed germination rate, germination potential, vigor index, fresh weight, seedling root length and seedling height, and relative salt damage rate were studied. The results showed that the germination percentage, germination index, vigor index, fresh weight, relative salt damage rate, root length and seedling length of seedlings increased first and then decreased with the increase of different sodium salt concentration, but the germination potential gradually decreased. The seeds were suitable for germination in low sodium concentration（Na⁺ concentration ranged from 0 to 25 mmol/L） environment. High concentration of sodium salt stress significantly inhibited seed germination and had a certain effect on seedling growth. Different kinds of sodium salts had different effects on seed germination. The salt tolerance of seeds in neutral salt was higher than that of basic salt and mixed salt. The maximum salt damage rate of seeds in two kinds of neutral salt was 73.91%, 52.17%, and the latter was 100%. The maximum germination rates of seeds under NaCl, Na₂SO₄ and Na₂CO₃ treatments were 73.69%, 74.5% and 66.54%, respectively, which were significantly different between neutral salt and alkaline salt treatments, and were more suitable for survival in neutral salt environment..There were differences for the limit of seeds in different sodium salts inspect of salt tolerance values. The limit salt tolerance values of basic salt and mixed salt appeared at the concentrations of 75 mmol/L and 150 mmol/L, respectively, but there was no limit salt tolerance value in neutral salt. The inhibition degree of different sodium salt stress on seed germination was : Na₂CO₃＞NaCl+Na₂CO₃＞NaCl＞Na₂SO₄. Seeds were more suitable to germinate in the environment of low concentration of neutral sodium salt. Robinia pseudoacacia seeds should be planted according to the content and type of soil salt.