Effects of timing of leaf removal on yield, berry maturity, wine composition and sensory properties of cv. Grenache grown under non irrigated conditions

Abstract

Aims: The objective of this study was to investigate the effects of timing of leaf removal on yield components, berry sensory characteristics, composition and sensory properties of Vitis vinifera L. Grenache wines under non-irrigated conditions.

Methods and results: The effects of timing of defoliation (fruit set and veraison) on yield components, berry maturity, wine composition and sensory properties of head trained, non irrigated, Grenache vines grown in Rioja appellation were studied. Leaf removal did not significantly modify total leaf area per vine as well as yield components. Grenache berries from early defoliated vines achieved the highest skin and technological maturity. Wine parameters, such as alcohol content, pH, titratable acidity, tartaric acid and total polyphenol index were unaffected by defoliation. Conversely, early leaf removal carried out at fruit set, significantly reduced the malic acid content of the wine and enhanced its colour intensity. Aroma complexity, mouthfeel, tannin quality and persistence were found to be significantly higher in the wine corresponding to the early leaf removal treatment. This was also the most preferred wine in terms of overall value.

Conclusion: This article shows that timing of leaf removal had a marked effect on berry maturity, wine composition and sensory properties of Grenache wines made from grapes grown under dry-farmed conditions.

Significance and impact of study: The results suggest that the timing of defoliation induces significant changes in Grenache wine composition and its sensory attributes. Late leaf removal was much less effective than early leaf removal in affecting final wine composition and quality. Grenache wine from the early defoliation treatment was rated the most preferred as of global value.