Quantification of leaf and grape removal consequences on chemical and sensory characteristics of grenache wines in Montsant region (Spain)

Abstract

Leaf and grape removal are antiques cultural practices used in Montsant region to improve wine color and structure of Grenache (Vitis vinifera L.). Nevertheless it has not been deeply studied the real consequences of the application of these techniques on grape composition and wine quality. The aim of this study was to quantify the effect of leaf and grape removal on yield, chemical and sensory characteristics of Grenache, under rainfed conditions. This study offers the growers a criterion to discriminate the suitability of the application of those cultural practices. A four treatment trial was designed on a non-irrigated vineyard: C: Control; LR: Leaf removal; GR: Grape removal; LR+GR: Leaf removal + Grape removal. Leaf removal was done after berry set, from the shoot base to the leaf opposite to the second cluster. Grape removal was done in veraison, leaving only one cluster per shoot.

Removing from 94.5 cm to 78 cm of  vegetation wall total height (23 % of External Foliar Surface), grape maturity analyses reported higher values of total and extractable anthocyanins, total phenols index, total tannins and color intensity in LR+GR than in C. This treatment was the best rated by a trained panel in sensory analysis. However, a yield loss of over 40 % was observed in LR+GR in comparison with C treatment. An increase in color was obtained in LR wines, but the excess of cluster sunlight exposure resulted in non-balanced wines in terms of sensory analysis. GR, which was the second best rated by judges, lost 29 % of yield respect to C and improved color intensity and phenolic content using 1.8 m2 of total leaf area per kilo of fruit produced.