Abstract: We usedpot cultivation with coastal soil containing total 3% salinity to identify the salt tolerance of 895 wild soybean plants collected in the Tianjin and Tangshan region of China, and to determine Na⁺, Cl^–, K⁺, Ca²⁺, Mg²⁺ contents in the stems and leaves of 203 plants that died at different stages and at maturity. The aim was to evaluate the differences of ion accumulations in the dead and survival wild soybean plants, and to discuss the mechanism of salt tolerance. The results showed that there were no significant differences in the content of every ion (Na⁺, Cl^–, K⁺, Ca²⁺, Mg²⁺) among these plants with a different survival time during the vegetative growth period. When the content of Na⁺ or Cl^– was accumulated to a certain high level in plants, the low salt-tolerant plants would be dead. Wild soybean individuals could die when their stems accumulated Na⁺ and Cl^– to the range of 3.239–4.682% and 4.639–6.328%, and their leaves accumulated Na⁺ and Cl^– to the range of 1.754–2.349% and 4.126–5.073%, respectively. The salt-tolerant plants could be divided into three types of low, moderate, and high levels in ion accumulations. The contents of Na⁺ and Cl^– in the stems and leaves of the high salt-tolerant plants were less than those of the low salt-tolerant ones. With survival time prolonging, the contents of K⁺ in the stems and Ca²⁺and Mg²⁺ in the leaves were increased. There were two types for the content levels of Na⁺ and Cl^– ions in stems and leaves of the survival plants, i.e. a low-level accumulation and a high-level accumulation, suggesting that the salt-tolerant wild soybean lines may have two kinds of mechanisms for the salt tolerance: one is high bearing and another is low absorption.

Key words: Glycine soja, Saline-alkali stress, Ions accumulation, Mechanisms of salt tolerance