Effect of shoot trimming on Yield, Fruit Maturity and Reserves in malbec vineyards under single high wire trellis system

GASTÓN E. AHUMADA; MIGUEL PIRRONE; SEGURA DANIELA; BELMONTE MARCELO; CARLA V. GIORDANO; CARINA V. GONZÁLEZ

Congreso; LXXII ASEV National ConferenceLXXII ASEV National Conference; 2021

Argentina is the world’s fifth largest wine producer and Malbec is its most emblematicvariety. Vineyards producing high-quality winegrapes are mainly trellised to verticalshoot-positioned systems. The single high-wire (SHW) system is a highly productivefree canopy trellising/training system used in many world wine regions. We evaluated,for the first time in Argentina, the effect of different shoot-trimming levels onleaf area development, yield, grape maturity, and reserve levels of Malbec (clone598) from SHW-trellised vineyards in Mendoza (Winkler = V). We imposed differenttotal leaf areas (TLA) by shoot-trimming, varying shoot length at full bloom (0.45 m,0.80 m, or untrimmed) during three growing seasons (2017, 2018, and 2019). Wemeasured yield and fruit composition at harvest and soluble and structural reservesin trunk and canes at leaf fall. Different shoot-trimming levels produced differenttotal leaf area development. The 0.8 m treatment produced 30% less TLA than theuntrimmed treatment, while the 0.45 m treatment produced 60% less TLA than theuntrimmed treatment, consistently among seasons. The treatments affected yield differentially by season. Overall, the untrimmed treatment had the greatest yields.The 0.80 m treatment, while producing high yields in the second season, was notsustained in the third season and declined to similar yield values as the 0.45 m treatment.This drop in yield could be due to the decrease of starch in the trunk duringthe second season. On the other hand, grape maturity was greater in the 0.80 m anduntrimmed treatments. Our results suggest that the untrimmed treatment producesgreater sustained yields over time, with good levels of reserves and grape maturity.