Evaluation of the influence of natural fertilizers in the phenolic composition during the maturation of the grape

Abstract

The use of natural fertilizers such as silicon and calcium chloride is a potential strategy to improve grape resistance versus fungal diseases due to changes in berries physical characteristic and secondary metabolites synthesis. The purpose of this work was to study the effect of calcium chloride and silicon on grapes phenolic composition during maturation. The experiment took place in a commercial vineyard, situated in the city of São Joaquim (28°17’38″S, 49°55’54″W, altitude 1.250 m), Santa Catarina, Brazil, 2017 vintage. The evaluated variety was Sauvignon Blanc. Treatments with calcium chloride (0; 0.5%; 1.0% and 1.5%) and silicon (0; 0.04%; 0.08% e 0.12% of Sodium metasilicate) were applied singly into vegetative period: buckshot berries, veraison, beginning of berry softness, and 15 days before the harvest. Grape berries were sampled four times during grape maturation. And total polyphenols, total flavanols, o-diphenols, browning index and antioxidant activity were analyzed. The phenolic composition has shown a significant difference (p<0.05) between control and the other treatments. The application of 0.5% of calcium chloride resulted in highest contents of total polyphenols and antioxidant activity. Berries treated with 0.08% and 0.12% of silicon, obtained highest values of phenolic composition and antioxidant activity. Further studies will be performed to determine the effect of this natural fertilizers on wine phenolic composition.