The effect of salicylic acid on antioxidant properties of "Shahani" and "Fakhri" grapes cultivars

Grape (Vitis vinifera L.) contains antioxidant compounds which are very useful for human. Unfortunately, most of the antioxidant compounds, such as flavenoides, are reduced during grape ripening stages. Therefore, the study of elicitors for increasing these compounds at the time of ripening, is necessary. In this study, the effect of salicylic acid (SA) spraying in three concentrations of 0 (control), 0.1 and 1mM on the leaves and fruits of two grape cultivars "Shahani" (with black berries) and "Fakhri" (with green berries) at two growth stages (unripe and ripe) were investigated. Detection indicators at unripe stage were acidity and berry size, and at ripe stage were juiciness and total soluble solid of berries . This study was conducted in 2013-2014 on the vineyards of the "Malayer Grape Research Center". The experimental vines were ten years old and their growing system was a row planting and drip irrigation method. This experiment was carried out based on completely randomized design (CRD) with seven treatments and three replications. The results showed that the maximum amount of carotenoids were at the unripe stage in the fruit skin of "Shahani" and "Fakhri" cultivars treated by SA at 0.1mM concentration to amount 73.65 and 69.94 mg/gFW, respectively. Results of comparing two growth stages showed that the maximum amount of anthocyanins were at ripe stages in the fruit skin and leaves of "Shahani" cultivar treated by SA at 0.1mM concentration to amount 3.21 and 2.343 mg/g FW respectively. In addition, Measurement of total flavonoids content as showed the increasing effect of SA at 0.1mM concentration on total flavonoids of leaves and all parts of fruits (exception of seeds) both "Shahani" and "Fakhri" cultivars at ripe stages were more effective. Also, SA treatment as significantly increased the antioxidant activity content of most parts both cultivars at unripe stages at 0.1mM concentration and ripe stages at 1mM concentration. These results showed that the use of common materials, such as SA, can greatly increase antioxidant properties of grapes during ripe stage.