The effect of the foliar application of potassium sulfate, potassiumnano chelate and humic acid at different concentrations (0, 1000 and 2000 mg/l) on the yield, qualitative and quantitative properties of the ‘Bidaneh Sefid’ grape cultivar were studied in a commercial vineyard over 2013-2015. Three foliar applications were considered: one application before flowering, two weeks after fruit development and one month after the second application. Based on the results, the highest concentration of potassium and zinc in leaves were obtained for 2000 mg.liter potassium sulfate. The maximum amount of phosphorus and iron in leaves were observed for potassium nano chelate at 2000 mg/liter. Also the treatment with 2000 mg.liter humic acid produced the largest leaf area (1207.7 cm2) compared with the control group. Potassium nano chelate fertilizer at the concentration of 2000 mg.l produced the greatest yield (128.7 kg.vine) and TSS (27.39%). Potassium sulfate and humic acid at the concentration of 2000 mg.l provided the highest levels of starch (81.87 mg/m FW) and carbohydrates (39.19 mg.g FW). The highest level of resveratrol (3.56 mg.g FW) was achieved in treatment with potassium nano chelate and humic acid of 2000 mg.l. It was concluded that potassium sulfate, potassium nano chelate and humic acid at 2000 mg.l have noticeable impacts on the quantitative and qualitative characteristics of the‘Bidaneh Sefid’ grape cultivar.
