Resumen de Efecto de la cubierta vegetal en el N del suelo, el N de la vid y en los aminoácidos de la uva
Eva Pilar Pérez Alvarez, Teresa Garde Cerdán, María Pilar Santamaría Aquilué, Enrique García-Escudero Domínguez, Fernando Peregrina Alonso
This study investigates the use of cover crops in La Rioja vineyards as a method of controlling both excess vigour and yield, which have a negative impact on must and wine quality. Basically, cover crops compete for soil water and nutrients. Recent studies indicate that cover crops decrease the availability of N in soil. This lower N availability may affect grape amino acids concentration. Amino acids are an important source of N for least but, some of them, are precursors of biogenic amines. Changes in the amino acid profile of grapes can modify the frermentation conditions and the compounds produced in it, thus affecting the wine quality. Therefore, the aim of this study was to determine the effect of the cover crop in the soil N availability, vine N nutritional status and grape amino acid composition. The trial started in 2009 on a cv. Tempranillo (Vitis vinifera L.) vineyard grafted on a R-110 rootstock, this vineyard was planted in 1999 with a density of 2,850 plants per hectare, the plot was located within the A.O.C. Rioja. Soil was classified as Oxyaquic Xerorthent, (Soil Survey Staff, 2006). Two treatments (conventional tillage and a barley cover crop (Hordeum vulgare L. cv. "Naturel") were randomly distributed within each of three blocks. In 2011 the soil was sampled (0-15 cm y 15-45 cm) at different moments of the vine phenology (budbreak, bloom, fruit-set, veraison, post-harvest), to determine the extractable NO3--N of the soil. At bloom, leaf samples (blade and petiole) were taken to determine the N content. Finally, at harvest, 500 grapes in each treatment were chosen at random to determine the amino acid content using liquid chromatography. Barley cover crop reduced the NO3--N availability from bloom (April) to post-harvest (November). At bloom, the N percentage in blade was lower for the barley cover crop. Concentrations of several amino acids, including Proline, were lower in barley treatment. Hence, cover crops can reduce soil N availability and vine N nutritional status, which in turn provokes the reduction of amino acid concentration in grapes.
