Irrigation effects on the agronomic and enological performance of godello cultivar from Valdeorras D.O. (northwest Spain) in 2012

Abstract

In recent years, an uneven distribution of rainfall in Galicia has been observed, the variations in the frequency and amount of rainfall increased the interest for irrigating the vineyards within the Galician wine sector. This study presents results from a trial undertaken at Valdeorras, one of the five Designations of Origin (D.O.) in Galicia. The grapevine cultivar under study was Godello, which is a white grapevine variety native from Galicia. The field experiment consists of three treatments: rainfed, surface and subsurface drip irrigation. In order to assess the water status of the vineyard, midday leaf water potential was  measured over the growing season. Production parameters were assessed by recording the number of clusters per plant, yield per plant and berry weight. Grapes harvested from each treatment were transported to the experimental winery of EVEGA (Estación de Viticultura e Enoloxía de Galicia) where microvinifications were developed. Analyzes were performed on musts and wines for assessing their pH, alcohol content, titratable acidity, tartaric and malic acids. No significant differences were detected in production parameters (yield, number of clusters per plant and berry weight) among the three treatments considered. However, a slightly higher yield per plant was recorded in the treatment of subsurface drip irrigation, which was caused by a higher cluster weight. A delay in maturation was observed in irrigated treatments over the rainfed control; in fact, musts from irrigated plants presented a lower pH, higher total acidity and less sugar content. This same trend has also been observed in the wines. For instance, wines from the irrigation treatments presented lower alcohol content, higher total acidity and lower pH. However, those differences were not significant.