Agronomic and enological potential of ‘Cabernet Franc’ and ‘Malbec’ produced under cycle inversion in subtropical climate in Brazil

ABSTRACT The cycle inversion technique enhances the maturation and health of grapes by shifting the harvest to months with milder temperatures and lower precipitation. This study aimed to characterize the ‘Cabernet Franc’ and ‘Malbec’, managed using this technique in São Roque, São Paulo, Brazil, focusing on productive parameters, the relationship between vegetative growth and fruit yield, and the evolution of technological and phenolic maturation of the berries. The experiment was conducted in a non-irrigated commercial vineyard, using a vertical trellis system and trained with bilateral spur cordon, over the 2020, 2021, 2022, and 2023 growing seasons. The results indicated that ‘Cabernet Franc’ produced an average yield of 1.71 kg per plant, with looser clusters averaging 64.2 g. On the other hand, ‘Malbec’ yielded an average of 3.12 kg per plant, with denser and heavier clusters averaging 114.3 g. Both cultivars exhibited a Ravaz index (RI) below the recommended threshold, with values of 1.9 for ‘Cabernet Franc’ and 3.6 for ‘Malbec’. Technological maturation followed a similar progression for both cultivars, with only minor differences. Total soluble solids accumulated to levels above 21 °Brix, and total acidity remained below the 5-6 g·L-1 range. Phenolic maturation, particularly in total polyphenols (TP) and total anthocyanins (TA), demonstrated a consistent accumulation trend throughout the maturation process. The ‘Cabernet Fran’ averaged 415.28 mgGAE·100 g-1 for TP and 279.67 mg·100 g-1 for TA, while the ‘Malbec’ showed significantly higher levels of 1,371.06 mgGAE·100 g-1 for TP and 726.18 mg·100 g-1 for TA.