21st GiESCO International Meeting: ‘A Multidisciplinary Vision towards Sustainable Viticulture’ CHANGES IN PHYTOCHEMICAL COMPOSITION OF GRAPES INDUCED BY THE APPLICATION OF CALCIUM CHLORIDE 1 1 1 2 2

Trilicia GOMES , Luíza FREITAS , Isabela TOALDO , Carolina PANCERI , Bruno MACHADO , Alberto BRIGHENTI3, BURIN Vivian1, Marilde BORDIGNON-LUIZ1* 1 UFSC, Federal University of Santa Catarina, CAL-CCA, Department of Food Science and Tecnhology, Florianópolis, Brasil. 2 IFSC, Federal Institute of Santa Catarina, Urupema, Urupema, Brasil. 3 EPAGRI, Agricultural Research and Rural Extension Company of Santa Catarina, São Joaquim, Brasil. *Corresponding author: marilde.bordignon@ufsc.br

Abstract: Context and purpose of the study - The application of fertilizers directly to the fruit is considered a form of fertilization favorable to the environment, because requires a smaller portion of the fertilizer and reduces the use of synthetic phytosanitary products. Exogenous fertilization with calcium is beneficial to plants, providing better growth and development. The use of calcium chloride has promising potential as a natural fertilizer. Considering the possibility of using this substance to increase vineyard productivity and the bioactive composition of grapes, this study evaluated the effects of different concentrations of calcium chloride in the productivity and phytochemical characteristics of Sauvignon Blanc grapes. Material and methods - The experiment took place in a commercial vineyard of Sauvignon Blanc grapes, situated in São Joaquim (28°17'38’ S, 49°55'54’ W, 1,250 m altitude), Santa Catarina, Brazil, 2018 vintage. Treatments of calcium chloride (0.0%, 0.5%, 1.0% and 1.5%) were applied in the vegetative period: buckshot berries, veraison, beginning of berry softness, and 15 days before the harvest. The productivity parameters evaluated were cluster number per plant, productivity (kg/plant), estimated productivity (T/ha) and average cluster weight (g). Samples were analyzed for polyphenols using the Folin-Ciocalteu assay and the antioxidant capacity was determined by the ABTS method. Phenolic acids were quantified by high performance liquid chromatography with diode array detector. Results - The application of calcium chloride resulted in higher production per plant (40 to 175% higher), and consequently higher yield per hectare of the vineyards (36 to 160% higher), higher number of bunches per plant (up to 1,175%) and higher bunch weight (up to 18%) when compared to the control treatment. The application of calcium chloride influenced significantly the concentrations of polyphenols in samples. The Folin-Ciocalteu reducing capacity was higher for the grapes treated with 1.5% of calcium chloride (604.79 mg GAE/L). These samples had the highest antioxidant capacity (884.97 µmol TEAC/L). These results may be explained by the fact that calcium promotes the increase of the polysaccharide content in the cell wall of the fruit and the permeability of the membrane, therefore, the resistance of the cell wall can be maintained, which prevents the oxidation of phenolic compounds. Among the phenolic acids, the derivatives of hydroxycinnamic acid were the most abundant in Sauvignon Blanc grapes. Their concentrations were significantly higher with the application of calcium chloride, particularly of ferulic, trans-caftaric and pcoumaric acids. Exogenous nutrition with calcium chloride is an alternative to increase the yield of the plant without damaging the phytochemical characteristics of the fruit and its products.

Keywords: Natural fertilizers, sustainability, Sauvignon Blanc, phenolic composition, vineyard productivity, viticulture.
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