Abstract:When barley ( Hordeum vulgare L. ) seedlings were treated with 100 mmol/L NaC1 for 2 d, the index of unsaturated fatty acid (IUFA) increased in the tonoplast vesicles that were isolated from the seedlings mots of two barley cultivars with different salt tolerance, whereas no change were observed when the seedlings were treated with exogenous fatty acids with different satumbility. Exogenous stearic acid and linoleic acid decreased Na + absorption and transportation to the shoots, increased K + absorption and transportation, decreased the leakage of electrolytes, and increased the phospholipid and galactose contents of lipids in tonoplast, enhanced the activities of tonoplast H+ -ATPase and H+ -PPase. This is consistent with the results that the two fatty acids, linoleic acid and stearic acid, regulate ion absorption and distribution, mitigate salt stress to some extent, the effects of linoleic acid being more the latter.