Background and aims: In recent years, increasing summer temperatures coupled with reduced and erratic rainfall during the growing season have induced accelerated fruit ripening in several regions, resulting in an undesirable increase in wine alcohol content. This study was designed to evaluate the impact of canopy and water management on grape sugar and flavonoid accumulation, with the goal of reducing wine alcohol content while conserving or enhancing flavonoid concentration.
Methods and Results: In 2011 and 2012, two irrigation treatments (I–irrigated and DI–deficit irrigated) and two canopy heights (HC–high canopy and SC–short canopy) were applied in a ‘Merlot’ vineyard. No interactions between treatments were observed, and thus, independent results were obtained; DI berries had significantly higher sugar concentration (+5%) than I in both years and higher wine alcohol content only in 2012. SC berries had lower sugar concentration (-4%) than HC and lower wine alcohol (-8%) only in 2011. Anthocyanins and tannins in berry and wine were increased by water deficit and not affected by severe trimming.
Conclusion: DI did not reduce berry sugar concentration and wine alcohol content but did enhance desirable wine attributes. SC reduced berry sugar concentration and alcohol content in wine in one of the two seasons. Water deficit and severe trimming showed independent effects on berry composition.
Significance of the Study: Severe canopy reduction performed at early stages of ripening can reduce sugars without affecting anthocyanin accumulation in ‘Merlot’. Conversely, deficit irrigation applied before veraison, despite promoting anthocyanin accumulation, may also increase berry sugar concentration at harvest.
