Qualidade e potencial antioxidante das uvas ‘Isabel Precoce’ e ‘BRS Cora’ em função de sistemas de condução, porta-enxertos e safras, em condições tropicais

Abstract

In tropical vitiviniculture, annual minimum temperatures are not enough to induce the dormancy, favoring two or more scheduled crops per year, in the same vineyard. Currently, the main region of tropical grape juice production in Brazil is the Submiddle of São Francisco Valley, based on the cultivars Isabel Precoce, BRS Cora, BRS Violeta and BRS Magna. In addition to the climatic conditions in each production season, the production system can also affect the quality and phenolic composition of the grapes, depending on the architecture of the canopy in each trellis system and the scion-rootstock interaction. Thus, the study had the aim of characterizing the quality and antioxidant potential of 'Isabel Precoce' and 'BRS Cora' grapes in different trellis systems and rootstocks, in four consecutive seasons. The experimental design was in randomized blocks, in sub-subplots through time, with four replications. Three trellis systems and two rootstocks were studied in cycles of the first and second semesters of 2017 and 2018. At harvest, bunch mass; berry mass; soluble solids content; soluble sugars; titratable acidity; resistance of the berry to the compression force; color attributes of skin L, a* and b*; anthocyanin and yellow flavonoid content in the skin; content of total extractable polyphenols in skin and pulp; antioxidant activity by the free radical capture methods ABTS●+ e DPPH● were evaluated. Trellis systems that allow greater interception of solar radiation, such as lyre and overhead trellis system, and less vigorous rootstocks, which provide greater opening of the canopy and consequent interception of solar radiation, have induced an increase in berry mass and soluble sugar content, as they contributed to the synthesis of phenolic compounds. Some components of grape quality and composition showed variations, even with climatic factors, trellis system, rootstock and the same genetic characteristics of the scion, indicating that other elements may influence them. Therefore, the choice of the trellis system and rootstock should consider the stability of the chemical compounds of commercial importance in the cycles of the same period of the year, in order to allow predictable quality of the grape and its derivatives throughout harvests.