Effects of Soil and Foliar Fertilizing on Afus Ali Grapevine Buds' Winter Temperature Resistance and Cluster Chemical Composition

Abstract

The aim of this research was to determine the influence of soil and foliar fertilizing on the chemical composition of the clusters and the resistance of the clusters to low winter temperatures of grapevine cultivar Afus Ali grown in the Tikves vineyard area. In November, with the basic cultivation of the soil, the fertilizer NPK 10-20-30 was applied (500 kg∙ha-1). Foliar fertilizing was performed with 0.4%, 0.8%, 1.2% and 1.5% solution of NPK fertilizer 18-9-27+2MgO + ME (1000 mg∙kg-1Fe; 200 mg∙kg-1 B; 150 mg∙kg-1 Zn; 500 mg∙kg-1 Mn; 56 mg∙kg-1 Mo; 110 mg∙kg-1 Cu). Four foliar treatments were applied during the vegetation: 15 days before flowering, 15 days after flowering, in the phase of grain growth and in the phase of verasion. In the soil samples, a neutral pH value was determined, medium fertility with available nitrogen and phosphorus as well as good fertility with available potassium. Different concentrations of foliar fertilizing had a positive influence on the chemical composition of the clusters and the resistance of the oaks to winter temperatures in which a significantly higher (p<0.05) content at all tested temperatures in all variants was obtained compared to the control area. In the clusters of the Afus Ali variety, higher (p<0.05) content of nitrogen (1.49%), phosphorus (0.69%) and potassium (1.12%), as well as the lowest percentage of frozen buds (5.80%) at a temperature of –15 °C, 9.00% frozen buds at a temperature of –18 °C and 17.87% frozen buds at a temperature of –21 °C was determined at the variant 4 (NPK 10-20-30 + 1.2% solution of NPK 18-9-27+2MgO+ME). The content of calcium (1.57%) and magnesium (0.40%) in the clusters was determined in variant 3 (NPK 10-20-30 + 0.8% solution of NPK 18-9-27+2MgO+ME).