Physicochemical characteristics of pomegranate fruits as affected by foliar application of potassium and zinc

Foliar application of mineral nutrients can considerably improve fruit yield and quality. In this study, the effects of K and Zn application by spraying on leaf mineral contents, and some physical and biochemical characteristics of pomegranate fruits cv. 'Malas Saveh' were investigated. The mineral treatments were three concentrations of K2SO4 (0, 1, and 2%) and three concentrations of ZnSO4 (0, 0.5, and 1%). The solutions were applied in 2020–2021 and in four times: the first application was during the time of flowering and rest three applications were applied at two-week intervals. The results showed that leaves of trees fed with different concentrations of K2SO4 and ZnSO4 accumulated higher concentrations of N, P K, Zn, Fe, and Mn than those untreated. Pomegranate trees treated with the mineral treatments had higher chlorophyll a and total chlorophyll. Applying most mineral treatments, especially 2% K2SO4+0.5% ZnSO4, significantly increased the fruit yield, fruit diameter, fruit length, aril percentage, aril/skin, the weight of 100 arils, and juice content of 100 g arils, but reduced the cracking percentage, skin thickness, skin percentage and firmness of fruits. Moreover, fruits of pomegranate trees treated with the most mineral treatments and especially 2% K2SO4+0.5% ZnSO4, showed a greater level of TSS (total soluble solids), TSS/TA (total soluble solids/titratable acidity), anthocyanin, total phenol, flavonoid, antioxidant activity, and vitamin C, and a lower level of TA. The study results evidenced that K and Zn application by spraying has a high potential for improving fruit yield and quality of pomegranate.