The effects of foliar spray of methyl jasmonate (MJ; 0, 50 and 100 µM) on phytochemical changes and nutritional balance of two grapevine (Vitis vinifera L.) cultivars [‘Sultana’ (as moderately salt-tolerant) and ‘Rishbaba’ (as a least salt-tolerant)] were evaluated under different saline conditions (NaCl; 0 and 75 mM). To explore optimum concentration of MJ treatment, grapevine plants were sprayed with MJ twice a day at 12-h intervals during the second week of salinity stress. The results showed that foliar spray of MJ especially at 100 µM was effective in alleviating deleterious effects of NaCl-induced salinity stress on both cultivars. The MJ at 50 and 100 µM significantly decreased ion leakage and production of malondialdehyde and hydrogen peroxide, but increased photosynthetic pigments, soluble carbohydrate, proline, and total phenol and flavonoid contents, especially in ‘Sultana’ compared with ‘Rishbaba’. Moreover, application of 100 µM MJ was associated with enhanced the activities of catalase, guaiacol peroxidase, and ascorbate peroxidase, resulting in greater leaf cell biomembranes stability in vines under saline condition compared with control plants (no treatment). The MJ was also associated with decreased accumulation of sodium and chlorine in leaves, but increased leaf minerals and trace elements compared with control vines. These findings suggest that foliar application of MJ, especially at 100 µM, might be useful to reduce negative effects of salinity stress in vineyards and nurseries.
