Abstract: In order to learn what role of carbohydrates content play in the plant adapting to salt soil, the structural and non-structural carbohydrates content in the leaves and roots of Leymus mollis and Calystegia soldanella grown in different distances from the high tide line and Na⁺ content in the soil and plants were tested. The results showed that in closed to high tide line with higher Na⁺ content in the soil, there were higher Na⁺ and water contents, soluble sugar and starch contents in the leaves and roots of L. mollis. With increasing distance far from the high tide line and decreasing of Na⁺ content in the soil, there were decreasec in Na⁺ content, soluble sugar and starch, increase in cellulose content and ratio of cellulose to total carbohydrate in the leaves and roots of L mollis. While, with far away high tide line, there were stable content of Na⁺, soluble sugar, increase in the starch content, decrease in the cellulose content in the leaves of C. soldanella. At same times, there were increase in the Na⁺, stable soluble sugar, decrease in starch and cellulose contents in the roots of C. soldanella. It indicated that L. mollis negetively accumulated Na⁺ and increase non-structural carbohydrates to maintain water balance of leaves and roots when there was higher Na⁺ content in the soil, used more non-structural carbohydrates to its growth and conversion to cellulose to built plant tissue when reducing of Na⁺ content. L. mollis and C. soldanella grown in different distances from the high tide line would increase its ability of holding water and taking up water by accumulating Na⁺ in the roots and leaves, and regulate the ratio of non-strutural and structural carbohydrates to total carbohydrates, which would be an important characteristics for them to adapt to different Na⁺ soil environment.

Key words: salt concentration, total carbohydrates, non-structural carbohydrates, structural carbohydrate