The purpose of this study was to assess how ‘IAC 572’, ‘IAC 766’, and ‘Paulsen 1103’ rootstocks affected the duration of phenological phases, thermal demand, and chemical evolution throughout production cycle of the ‘BRS Vitória’ table grape cultivated in subtropical conditions. The duration of the following phenological stages was measured in days after pruning throughout two production seasons: budburst, flowering, setting, veraison, and harvest date. The thermal demand was determined using the degree-day concept. Titratable acidity, pH, soluble solids, and the maturation index were all measured throughout berry maturation. In general, the rootstocks ‘IAC 572’ and ‘IAC 766’ increased vine precocity in comparison to ‘Paulsen 1103’ during the early phenological phases. However, the vines grafted on ‘Paulsen 1103’ were earlier in the later phases, that is, at the veraison and at the harvest date, when compared to those grafted on the rootstocks ‘IAC 572’ and ‘IAC 766’. Under subtropical conditions, the total cycle period of the ‘BRS Vitória’ vine varied from 131 to 143 days, with thermal demands ranging from 1,545 to 1,725 DD. In comparison to the ‘IAC 572’ and the ‘IAC 766’, the ‘Paulsen 1103’ supplied the berries with a higher accumulation of soluble solids and a higher maturation index.

Brazil has emerged as a significant producer of seedless grapes due to high consumer demand. This has led to increased production of seedless grapes in non-traditional cultivation regions, such as subtropical areas. To meet this demand, the search for new grape varieties suitable for these conditions, such as the ‘BRS Isis’ variety, has become an option for growers. The interaction between grape cultivars and rootstocks is specific, and their adaptability to climatic conditions can result in uneven performance. Therefore, the choice of rootstock should be considered before making any recommendations. The purpose of this study was to assess the productive performance, physical-chemical, and biochemical properties of the ‘BRS Isis’ vine grafted onto rootstocks (‘IAC 572’, ‘IAC 766’, and ‘Paulsen 1103’) in two production cycles. The experimental design consisted of randomized blocks, with seven blocks and three plants per plot, for a total of 63 vines. Thus, the vine’s income components, physical qualities of bunches and berries, chemical profile, bioactive substances, and antioxidant activity were assessed. The Tukey test (5% probability) was used to compare means between rootstocks. The data on scion cultivar and rootstock pairings were further evaluated using principal component analysis (PCA). There were substantial variations in the rootstocks, with ‘IAC 572’ and ‘IAC 766’ producing more bunches, generating more fresh mass, and having a longer bunch length than ‘Paulsen 1103’. However, phenolic compounds and flavonoids were greater in ‘BRS Isis’ grapes than in ‘Paulsen 1103’. ‘BRS Isis’ shows good adaptation to subtropical environments when employing the IAC 572 and IAC 766 rootstocks due to their higher yield and bioactive component accumulation compared to grapes grafted onto ‘Paulsen 1103’. However, regardless of the rootstock utilized, ‘BRS Isis’ grapes perform well commercially in subtropical environments.

The production of winter wines in Southeastern Brazil represents a relatively recent but expanding viticultural approach, with increasing adoption across diverse wine-growing regions. This system relies on the double-pruning technique, which allows for the harvest of grapes during the dry and cooler winter season, favoring a greater accumulation of sugars, acids, and phenolic compounds. This study aimed to characterize the phenological stages, thermal requirements, yield, and fruit quality of the fine wine grape cultivars ‘Sauvignon Blanc’, ‘Merlot’, ‘Tannat’, ‘Pinot Noir’, ‘Malbec’, and ‘Cabernet Sauvignon’ under double-pruning management in a subtropical climate. The vineyard was established in 2020, and two production cycles were evaluated (2022/2023 and 2023/2024). Significant differences in the duration of phenological stages were observed among cultivars, ranging from 146 to 172 days from pruning to harvest. The accumulated thermal demand was higher in the first cycle, with a mean of 1476.9 growing degree days (GDD) across cultivars. The results demonstrate the potential of Vitis vinifera L. cultivars managed with double pruning for high-quality wine production under subtropical conditions, supporting the viability of expanding viticulture in the state of São Paulo. ‘Cabernet Sauvignon’ and ‘Sauvignon Blanc’ showed the highest yields, reaching 3.03 and 2.75 kg per plant, respectively, with productivity values of up to 10.8 t ha⁻¹. ‘Tannat’ stood out for its high sugar accumulation (23.4 °Brix), while ‘Merlot’ exhibited the highest phenolic (234.9 mg 100 g⁻¹) and flavonoid (15.3 mg 100 g⁻¹) contents. These results highlight the enological potential of the evaluated cultivars and confirm the efficiency of the double-pruning system in improving grape composition and wine quality in non-traditional viticultural regions.