Effect of Potassium Sulphate Foliar Application on Some Quantitative and Qualitative Traits of Grape (Vitis vinifera L.) cv. Rashe

In this study, the effects of foliar application of potassium sulfate were evaluated on yield and quality of grape (Vitis vinifera cv. Rashe). Five foliar spray treatments including control, once foliar spray at two concentrations of 1.5 g.l-1 and 3 g.l-1 and two foliar sprays at two concentrations of 1.5 g.l-1 and 3 g.l-1 were used. The first and second foliar spray were done at the end of flowering period and fifteen days after the first spraying, respectively. The results showed that the average berry and cluster weight, total soluble carbohydrates and vitamin C significantly increased compared to control in potassium applied treatments. The difference was not significant between different treatments of potassium sulfate. Foliar application of potassium sulfate significantly increased the average berry volume, berry pulp and berry skin anthocyanin. Twice foliar applications of potassium sulfate treatment at concentration of 3 g.l-1 had the highest amounts of anthocyanin contents. Potassium-sprayed treatments increased total soluble solids and pH of the fruit juice. Titratable acidity was at least in 3 g.l-1 treatment and other treatments were not significantly different. In general, the results of this experiment showed that foliar application of potassium sulfate improves the quantity and quality of the grape berry.