Abstract

"During growing seasons 1998/99, 1999/2000 and 2000/01 a field trial on grapevines (Vinis vinifera L.) cv. Chardonnay was carried out with the objective of evaluating the effects of water stress on yield, wine quality, plant water status and nutritional reserves in the roots. The following treatments were applied: T1 and T2, application of water equivalent to 100% and 40%, respectively, of crop evapotranspiration (ETc) for the entire season; T3, no irrigation from bud formation to veraison and irrigation at 100% of ETc from then to harvest; T4, irrigation at 100% of ETc from bud formation to veraison and no irrigation from then to harvest. Water shortage significantly decreased shoot growth and berry diameter, which resulted in yield reduction. The growing period from bud formation to veraison had the largest reductions of these variables. On the other hand, the water deficit induced a decrease of carbohydrate reserves of the root system. Total acidity, global wine quality and phenols present in the wine did not increase with water stress, different behavior than that observed in red wines. The stem water potential (SWP), measured at noon, was a good indicator of plant water stress. Grapevines not submitted to water stress had SWP of over -0.8 Mpa, while those plants under water stress had values of -1.2 MPa."