Effect of Foliar Application of Zinc, Boron and Silicon on Growth and Fruiting of Balady Mandarin Trees

Abstract

This study was carried out at the experimental orchard, Faculty of Agriculture, Assiut University, Egypt, to investigate the effect of boron, zinc and silicon foliar spray on growth and fruiting of Balady mandarin trees during 2016 and 2017 seasons.The experiment was arranged in a randomized complete block design with three replications per treatment, one tree each. Boric acid (17% B), zinc sulphate (23% Zn) and potassium silicate (25% Si + 10% K 2 O) were sprayed three times on March, May and August. The obtained results could be summarized as follow:Spraying either boron, zinc or silicon singly or in combination significantly increased the growth traits and the total chlorophyll as well as the total carbohydrates, nitrogen content and C/N ratio of shoots compared to water spraying (control).The maximum values of these traits were recorded on trees that were sprayed with combination of 0.025% boron, 0.050% zinc and 0.10% silicon followed by silicon, zinc and boron spray, boron or zinc as well as zinc or silicon.All treatments significantly increased the fruit retention percentage and yield/tree compared to the untreated one.All foliar application treatments improved the fruit quality in terms of increasing the fruit weight, pulp percentage, total soluble solids, sugar and vitamin C contents and decreasing the total acidity compared to spraying water (control). The best fruit quality was recorded when the trees were sprayed with combination of boron, zinc and silicon.It is evident from the foregoing results that the foliar application of boron, zinc, silicon alone or combination improved the tree nutrient status, yield and fruit quality.As a conclusion it is suggested to use boric acid at 0.050%, zinc sulphate at 0.10% and potassium silicate at 0.2% (as a source of silicon) alone or a combination of boron 0.025, zinc 0.050 and silicon 0.10% three times during growth season for improving the growth and fruiting of Balady mandarin trees.