Foliar nutrient applications to 'Wonderful' pomegranate (Punica granatum L.). II. Effects on leaf nutrient status and fruit split, yield and size

Though pomegranates are beginning to be farmed more intensively, little is known about pomegranate leaf nutrient concentrations or the effects of foliar nutrient applications on those concentrations, including for one of the industry's standard cultivars, Wonderful. Foliar nutrient applications could potentially be used in commercial pomegranate production, not only to improve plant nutrient status, but also to prevent physiological disorders, such as pomegranate fruit split, the most important physiological disorder in pomegranate production. Pomegranate trees at two 'Wonderful' commercial orchards were treated with foliar applications of zinc sulfate (ZnSO4; 0.3%, 0.4%, and 0.5%), magnesium sulfate (MgSO4; 1%, 2%, and 3%), potassium nitrate (KNO3; 1%, 2%, and 3%), or deionized (DI) water (control). Leaf mineral nutrient concentrations were determined and fruit were analyzed for fruit split incidence, yield, fruit number per tree, fruit diameter, fruit mass, aril mass, and mass of 100 arils. Leaf Zn concentrations were significantly higher in response to all foliar ZnSO4 treatments. Foliar applications of KNO3 resulted in significant increases in leaf N and K concentrations and foliar MgSO4 resulted in a significant increase in leaf S concentration. All foliar fertilizer types resulted in significantly lower fruit split incidence at one of the study sites. The foliar fertilizer treatments did not have a significant effect on fruit number per tree, fruit diameter and mass, mass of all arils in fruit, or mass of 100 arils. The results suggest that foliar ZnSO4, MgSO4, and KNO3 could be used to improve pomegranate nutrient availability and to decrease pomegranate fruit split incidence without negatively impacting fruit yield or size of 'Wonderful' pomegranate.