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-1 ) 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. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of two doses of urea foliar application on leaves and grape nitrogen composition during two vintages.

BACKGROUND: Nitrogen affects grapevine growth and also yeast metabolism, which have a direct influence on fermentation kinetics and the formation of different volatile compounds. Throughout the grapevine cycle, soil nitrogen availability and grape nitrogen composition can vary because of different factors. Nitrogen foliar applications can contribute toward enhancing grapevine nitrogen status and minimize the problem of leaching that traditional nitrogen-soil applications can provoke. The present study aimed to evaluate the influence of urea foliar applications on grapevine nitrogen status and grape amino acid content. Accordingly, two different doses of urea were applied over the leaves of a 'Tempranillo' vineyard. RESULTS: The highest urea doses affected nitrogen content on blade leaf tissues after veraison. Must amino acid profiles were modified by urea application and some of the compounds increased their concentrations. The effect of year on the increase of must total amino acid concentrations was more important than the effect of the doses applied. CONCLUSION: Urea foliar applications can be an interesting tool for decreasing grapevine nitrogen deficiencies. This method of nitrogen implementation in the vineyard could avoid sluggish fermentation problems during winemaking, enhance must nitrogen composition, and contribute to improving wine quality. © 2016 Society of Chemical Industry.