Effect of Potassium Sulfate and Zinc Sulfate Foliar Spray on some Physical and Chemical Traits of Grape (Vitis vinifera cv. Bidaneh Ghermez)

In order to study the effects of foliar application of Potassium sulfate and Zinc sulfate on some physical and chemical properties of grape (Vitis vinifera cv. Bidaneh Ghermiz) berries, a factorial experiment was accomplished based on a randomized complete block design with three replications. The treatments comprised of potassium sulfate in three levels (0, 5 and 10 g L-1) and zinc sulfate in four levels (0, 5.0, 1and 2 g L-1). The solutions were sprayed on grape plants for three times during the growth season. The results showed that the maximum length of berries was observed in plants treated simultaneously with 10 g L-1 of potassium sulfate and 0.5 g L-1 of zinc sulfate. Also, the highest fruit width, cluster width, and number of berries per cluster were obtained from 10 g L-1 of potassium sulfate and 2 g L-1 of zinc sulfate. The highest TSS and the lowest pH were observed in the spray solution containing 10 g L-1 of potassium sulfate with 2 g L-1 of zinc sulfate. Total antioxidant, total flavonoid and catalase enzyme activity were significantly affected by foliar application. Total phenol and guaiacol enzyme activity were increased by spraying potassium sulfate or zinc sulfate but the interaction effect of potassium sulfate and zinc sulfate on these parameters was not significant. Therefore, it can be concluded that simultaneously foliar application of potassium sulfate and zinc sulfate may lead to increasing some secondary metabolites, enhancing antioxidant capacity and improving physical properties of grape (Vitis vinifera) cv. Bidaneh Ghermiz.