Foldable lyre as an alternative to improve yield and oenological potential of grapes for a sustainable viticulture

Abstract

Actually, many countries around the world are studying different strategies for adapting winegrowing regions to climate changes, focusing on a sustainable viticulture. There are many ways trying to mitigate the effect of global warming on wine sector, including the use of disease-resistant varieties, new clones of cultivars, new rootstocks, new enological protocols for winemaking, such as autochthonous yeasts producing lower alcohol content. Other possibilities are changing grapevine canopy architecture, the vineyard orientation, and new training and trellising systems. Serra Gaucha is the most important Brazilian winegrowing region, located in Southern in a humid temperate climate. In 2023, the country produced around 300 million liters of wines, composed by 80-85% from Vitis labrusca grapes, and15-20 % from Vitis vinifera L. In 2002, the first Geographical Indication of the country (as Protected Indication of Origin-PI) was recognized, named Vale dos Vinhedos, including more than twenty varieties authorized. In 2012, this PI became a Controlled Designation of Origin-DOC, and Merlot Noir was the only variety allowed for red wines. This study aimed to evaluate and compare the impact of vertical shoot positioning (VSP) and foldable lyre training systems, using three different angles (20°, 30°, and 40°), on vine development, physiology and yield, as well as on oenological potential of Merlot Noir grapes at Serra Gaucha, in two vintages (2022 and 2023). In 2022 season, the cycle between pruning and harvest was 161 days; while in 2023 was 193 days. The leaf and yield of the lyres systems were around 50% higher as compared to VSP, but no significant differences were observed for physiological parameters. The oenological parameters of grapes presented significant differences, except for total soluble sugars. In 2022, total anthocyanins was higher in the treatments VSP, 30º and 40º than 20º, while in 2023 vintage, 20º was higher than other. For tannins, foldable lyre at 40º presented the highest values. Foldable lyre showed that can be an alternative to wine sector in the region, increasing the yield and improving oenological potential of Merlot Noir grapes. The system proposed can be easily transformed in VSP, by using an adjustable closure mechanism. It allows mechanization of all vineyard management, including winter pruning, shoot topping and mechanical harvesting, thus reducing production costs and going to a sustainable viticulture.