Use of Minimal Pruning to Delay Fruit Maturity and Improve Berry Composition under Climate Change

Abstract

Minimal pruning (MP) is a technique used to reduce labor costs and produce high-quality winegrapes. To evaluate the effects of MP on grapes cultivated in warm-climate regions, a long-term study on Tempranillo (Vitis vinifera L.) was conducted in Badarán, La Rioja, Spain. For each vintage between 1999 and 2013, yield and total soluble solids (TSS) were evaluated in grapes from MP vines and from conventionally hand-pruned (CHP) vines. In 2014 and 2015, grapes were analyzed at 22 Brix to assess the effects of MP on fruit maturation and quality. The long-term study showed that MP increased yield by 56% and reduced TSS by 9% compared to CHP. Results from 2014 and 2015 demonstrated that MP delayed fruit maturity (22 Brix) by ~17 days. At the same TSS level (22 Brix), MP vines had 24% lower berry weight, 57% lower cluster weight, and 51% greater yield. Must from MP fruit had greater total anthocyanin concentrations compared to must from CHP fruit (+17% in 2014 and +21% in 2015); however, potential improvements in wine color were more likely due to smaller berry size than to greater anthocyanin synthesis per unit area of berry skin. These results indicate that MP can delay berry ripening and may help to improve wine color.