On-vine grape drying combined with irrigation allows to produce red wines with enhanced phenolic and rotundone concentrations

•We studied the impact of on-vine grape drying on grape and wine characteristics, and rotundone.•We showed that the technique had a limited impact on rotundone in wine which suggests that the compound is not translocated.•On-vine grape drying combined with irrigation allowed to produce wines with enhanced phenolic and rotundone concentrations.•Irrigation is likely to have a direct effect on rotundone accumulation rather than an indirect one through a modification in bunch microclimate.

Rotundone, the compound responsible for peppery aroma in red wines is positively correlated with the absence of water deficit during ripening which can make it problematic to produce red wines combining both superior concentrations in rotundone and phenolic compounds. To reach this double objective, on-vine drying with cutting of the fruit bearing cane or “Passerillage Éclaircissage sur Souche” (PES), a technique that consists in cutting the cane 2-3 weeks prior to harvest on a Guyot-trained vineyard was investigated combined or not with irrigation. We showed that PES had a limited impact on rotundone in wine. As the PES technique leads to an interruption of the sap flow, our results suggest that rotundone is synthesized in the berries and not translocated. A viticultural system combining irrigation and then PES induced significant gains in rotundone, in sugar concentration, in anthocyanins and in Total Phenolic Index in wine, and in skin to juice ratio. Measurements of bunch surface temperature indicate that the enhancement of rotundone production induced by irrigation is likely to be due to a direct rather than to an indirect effect through an increase in leaf area leading to a cooler bunch microclimate.

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