Effect of four levels of water application on grape composition and midday stem water potential of Vitis vinifera L. cv. Cabernet Sauvignon

An experiment was carried out to study the effect of four level of water applications on grape composition and midday stem water potential of a ribs vinifera L. cv. 'Cabernet Sauvignon' vineyard, located in the Pencahue Valley, Maule Region of Chile (35 degrees 22' S; 71 degrees 47' W), during the 2001-2002 growing season. The 9 year-old vines were irrigated by drip irrigation and trained on vertical shoot positional system. Levels of water application were: treatment T1 = 100 % of vine evapotranspiration (ET) during set-harvest, treatment T2 = 70 % of ET during fruit set-veraison and 40 % of ET during veraison-harvest; treatment, T3 = 40 % of ET during fruit set-veraison and 70 % of ET during veraison-harvest, and treatment T4 = 40 % of ET during fruit set-harvest. Results indicate that there were not significant differences in soluble solids (SS) and pH among treatments, but total yield was statistically higher in treatment T1 than others treatments. A significant reduction of berry diameter was found in treatments T3 and T4, which presented the highest concentration of total phenols. For this level of water application, midday water potential (Psi(stem)) at veraison was -1.29 MPa for treatment T3 and -1.24 MPa for treatment T4. On the other hand, treatment T1 presented the highest values berry size and the lowest concentration of total phenols and total anthocyanin. In this case, values of midday Psi(stem) ranged between -0.75 MPa and -0.98 MPa from set to harvest.