Effects of pre-harvest techniques in the control of berry ripening in grapevine cv. Sauvignon blanc

Due to a variety of reasons (changing climatic conditions, higher photosynthetic efficiency of newly established vineyards, yield restriction imposed by production protocols), there is currently a tendency towards early ripening in grapevines, combined with the production of berries characterized by high sugar content. This tendency conflicts with the general market demand for wines (mostly white wines) with low alcohol level and characterised by a fresh, easy-to-drink taste. We tested two different techniques applied to the canopy (defoliation and the use of an antitranspirant product) with the aim of delaying the ripening process and improving the berry quality of the white cultivar Sauvignon blanc. The defoliation performed at veraison allowed postponement of the ripening process by about 5 days as compared to undefoliated vines, without altering the sugar/acid ratio of the berries. The antitranspirant product delayed ripening by 10 to 15 days. Brix was reduced by 1.5-2.5 degrees in the 2 considered seasons, whereas the effect on acidity was contradicting and needs further research for a full understanding of the mechanisms involved in the process