Evaluation of foliar applications of urea at three concentrations on grape amino acids composition

BACKGROUND: Grape nitrogen composition directly affects the development of alcoholic fermentation and also influences the final wine aromatic composition. Moreover, different factors influence grape amino acids composition, such as rate and timing of nitrogen application. The aim of this study was to determine the influence of three doses of urea, applied at two different phenological stages (pre-veraison and veraison), on the nitrogen composition of Tempranillo grapes during two consecutive seasons. RESULTS: Urea treatments did not affect vineyard yield, oenological parameters of the grapes and yeast assimilable nitrogen. However, amino acids concentration in the musts increased at both moments of urea application (pre-veraison and veraison), but the lower urea concentrations and sprayed at pre-veraison improved most of the amino acids in the musts, during two vintages. Moreover, when the year was rainy, the higher dose treatment (9 kg N ha) applied at pre-veraison and veraison improved the amino acid concentration in the must. CONCLUSION: Foliar applications of urea could be an interesting viticulture practice in order to increase the amino acids concentration in Tempranillo musts.The authors thank the European Regional Development Fund (ERDF) and Government of La Rioja for financial assistance provided to the projects P.R.03-18 and P.R.03-19. R. Murillo-Peña thanks the National Institute for Agricultural and Food Research and Technology (INIA) and Government of La Rioja for her predoctoral contract