IMPROVING THE BUDS' WINTER TEMPERATURE RESISTANCE AND CLUSTER CHEMICAL COMPOSITION FROM ‘CARDINAL’ GRAPEVINE USING SOIL AND FOLIAR FERTILIZATION

Abstract

Grapevine (Vitis vinifera L.) is one of the most economically important productive drought stress-adapted crops grown globally. Fertilization is an important agrotechnical measure, where by applying optimal doses and types of fertilizers in an appropriate period, it is possible to significantly influence the development of the grapevine, and thus the production of high-quality grapes. This research aimed 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 ‘Cardinal’ grown in the Tikves vineyard area, North Macedonia. 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). 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 ‘Cardinal’ cultivar, higher (p<0.05) content of nitrogen (0.98%), phosphorus (0.98%) and potassium (1.03%), as well as the lowest percentage of frozen buds (6.05%) at a temperature of –15 °C, 8.85 % frozen buds at a temperature of –18 °C and 18.10% 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 highest content of calcium (1.73%) and magnesium (0.51%) in the clusters was determined in the variant 3 (NPK 10-20-30 + 0.8% solution of NPK 18-9-27+2MgO+ME).