Improvements in the aromatic composition of Tempranillo Blanco grapes after being sprayed with three concentrations of urea either at pre-veraison or veraison

Abstract

Primary aromas are important to define the quality of grapes and wines. This work studied the effect of the foliar application of urea in Tempranillo Blanco grapevines. The goal was to assess the effect of applying three doses of urea at two phenological stages (pre-veraison and veraison) on the volatile composition of Tempranillo Blanco grapes, during two seasons. The urea treatments did not have an impact on the vineyard yield or general parameters of the grapes. Nevertheless, these treatments modified the grape volatile composition. Specifically, the lower urea dose improved terpenoids, C₁₃ norisoprenoids, and benzenoid compounds. The application moment had a slight effect on grape volatile compounds. Moreover, the concentration of some terpenoids increased when urea was applied at veraison. Climatic conditions, especially warm and dry weather, were the main factors that modified the volatile compounds, stimulating the synthesis of C₁₃ norisoprenoids and benzenoid compounds. Consequently, foliar applications of low urea concentrations could be an interesting viticulture practice in order to improve volatile compounds in Tempranillo Blanco musts.