INFLUENCE OF ROOTSTOCKS AND TRAINING SYSTEMS ON BIOACTIVE COMPOUNDS AND ANTIOXIDANT ACTIVITY IN THE SKINS AND PULPS OF Vitis labrusca AND BRAZILIAN HYBRID GRAPES

Bioactive compounds in grapes, such as phenolics and anthocyanins, are valued for their antioxidant properties and health benefits. Agronomic factors, such as rootstocks and training systems, can influence these compounds. This study aimed to evaluate the influence of rootstocks and training systems on the bioactive compounds and antioxidant activity in the skins and pulps of Vitis labrusca and Brazilian hybrid grapes. Grapes from an experimental site located in Jundiaí, São Paulo, Brazil (23º 06’ S, 46º 55’ W, and 745 m altitude) were analyzed using a completely randomized design with a 2 x 2 factorial scheme, comprising two rootstocks (‘IAC 766 Campinas’ and ‘106-8 Mgt’) and two training systems (low and high vertical shoot positioning). Total phenolic compounds, flavonoids, monomeric anthocyanins, and antioxidant activity (assessed by DPPH and FRAP assays) were measured in the skins and pulps of Vitis labrusca (‘Bordô’ and ‘Isabel’) and hybrid grapes (‘IAC 138-22 Máximo’ and ‘BRS Violeta’). Data were subjected to analysis of variance, and means were compared using Tukey's test (p < 0.05). The results demonstrate that both rootstock and training system significantly affect the bioactive compound content and antioxidant activity in Vitis labrusca and Brazilian hybrid grapes. Grapes on the ‘IAC 766 Campinas’ rootstock and trained with the high vertical shoot positioning system had higher concentrations of phenolics, flavonoids, and anthocyanins, as well as improved antioxidant activity. These findings suggest that this combination enhances the bioactive quality of the grapes, offering potential benefits for both fruit quality and health.