Impact of foliar sprays of potassium, calcium, and boron on fruit setting behavior, yield, and quality attributes in fruit crops: a review

Plant nutrients are chemical elements necessary for plant growth and its metabolism. The external application of mineral nutrients modifies as well as regulates the physiological processes when applied directly to leaves in small concentrations. Plants can absorb essential elements via stomata and epidermis present in leaves. Plant nutrients applied to leaves are more rapidly absorbed as compared to soil application. Foliar application for supplementing the nutrient requirement of fruits crop appears to be more practical method being target-oriented as well as environmentally friendly. Fruits are high-value crops being perennial in nature are exposed to abiotic stresses during their life and even a little alteration in productivity, quality, or improved cosmetic appeal can increase fruit value immensely. Foliar application of various nutrients like potassium, calcium, and boron proved to be efficacious in increasing fruit set, retention, yield attributes as well as quality apart from reducing fruit drop in fruit crops. In this review, the role of macronutrients, that is, potassium and calcium in addition to micronutrient boron in fruit crops such as foliar sprays are discussed.