Impact of the vine water status on the berry and seed phenolic composition of 'Merlot' (Vitis vinifera L.) cultivated in a warm climate: Consequence for the style of wine

During 2005 and 2006 four irrigation treatments were assayed in a vineyard growing 'Merlot' grapes located in a warm climate region. The treatments were kept for two years and the wine was produced the second year so that the response of the wines to water constraint was consistent. The phenolic parameters of the wines were analysed. The phenolic composition of the seeds was studied for both years and more significant differences were observed in the second. The results showed that when the deficiency increased, so did the concentration of total polyphenols, flavan-3-ols and tannins in the seeds. Pre-dawn leaf water constraint integrals between 20 and 24 Mpa as opposed to levels of 9 to 14 caused statistically significant increases in total polyphenols, flavan-3-ols and the colour index of the wine. These differences were manifested in sensory terms by significant intensification of the colour and body of the wines.