Salicylic acid (SA) is an endogenous growth regulator that participates in the regulation of physiologic processes in plants. It plays an important role in plant response to adverse environmental conditions. In this study, SA in three concentrations—0, 0.1mM, and 1m—was sprayed on the leaves and fruits of two grape cultivars (Bidane Ghermez and Bidane Sefid) at two growth stages: unripening and ripening. The SA 0.1-mM concentration effectively increased leaf chlorophyll a of the Bidane Sefid cultivar at both growth stages. Chlorophyll b and proline of the leaves and berry skin of both cultivars increased at both growth stages under SA treatment, especially with the 0.1-mM concentration. The SA 0.1-mM concentration increased carotenoids in leaves and berry skin of Bidane Ghermez cultivar at both growth stages and of Bidane Sefid cultivar in the unripening stage. The SA 0.1-mM concentration was also associated with increased soluble sugars of the leaves and berry skin of both cultivars at both growth stages. However, the effect of SA on insoluble sugars was different. At the unripening stage, the SA 1-mM concentration significantly increased the total protein of the berry flesh and leaves of Bidane Sefid. The results show that in both growth stages, the SA treatment, especially the 1-mM concentration, effectively increased the superoxide dismutase (SOD) enzyme activity of leaves, skin, and flesh of berries of both cultivars. The results indicate that SA treatment in grapes may stimulate the synthesis of some photosynthetic pigments, carbohydrates, proline, protein, and SOD enzymes.
