Épocas de poda e sua influência na fenologia, produtividade e qualidade em cultivares de videiras em Dom Pedrito, RS, Brasil

Abstract

This study aimed to evaluate the influence of pruning times on vine phenology, productivity, and quality of grapes and wine of different cultivars in the 2022/2023 production cycle. The experimental design was in randomized blocks, with 3 replications, and the experimental unit consisted of 5 plants. The treatments consisted of four pruning times (at the end of May, June, July and August), carried out on four cultivars of Vitis vinifera L. (Cabernet Sauvignon, Merlot, Sauvignon Blanc and Chardonnay), with phenology evaluations (in beginning and end of budding, flowering, and maturation), percentage of bud sprouting, production and quality of the grape and wine. Production was evaluated in number of bunches per plant; average weight and size of bunches; productivity per plant and per hectare. Analyzes of must before processing, and wine, were performed, these being pH; total acidity; sugars and soluble solids (°Brix). Analyzes of pH, total acidity, sugars, alcohol and volatile acidity were carried out in the wine, in addition to analyzes of color, tannins, anthocyanins and ionization index in red wines. The budding of plants of cultivars pruned early, in May, occurred at the same time as plants pruned in June and July, with the exception of the Chardonnay cultivar. Early pruning, carried out in May, reduces the duration of the phenological cycles, with the exception of Sauvignon Blanc, where the different pruning times did not influence. Early pruning of Chardonnay and Merlot can increase the risk of late frosts in years with severe winters. For Cabernet Sauvignon and Chardonnay, early pruning resulted in lower production. For Merlot, the highest yields were in May and July. Sugars for Chardonnay denoted the highest values for plants pruned in May, and Sauvignon Blanc for plants that were pruned at the time established by the producer in July. The must of all cultivars with late pruning, in August, presented higher total acidity, with the exception of Chardonnay; and minors for soluble solids and sugars, including Chardonnay. Early pruning increased the accumulation of tannins and anthocyanins in red cultivars. Early pruning did not alter the duration of the phenological subperiods of the studied cultivars, nor did it bring forward the harvest, in relation to the control. However, especially in Chardonnay and Merlot, it can favor the risk of damage to shoots by late frosts, in winter years with temperatures close to 0°C. The different pruning times influenced the productivity more than the composition of the grapes and wines. Therefore, it is possible to extend the period of pruning at the time adopted by the producer. In this way, it is possible to schedule and optimize the workforce for carrying out dry pruning.