Effect of Foliar Applications of Proline, Phenylalanine, Urea, and Commercial Nitrogen Fertilizers on Stilbene Concentrations in Tempranillo Musts and Wines

Abstract

Resveratrol-enriched wine is considered a product with added value because of the numerous health-promoting properties of this compound. The purpose of this study was to determine the effect of foliar nitrogen application on stilbene concentrations of Tempranillo musts and wines. The nitrogen sources applied were proline, phenylalanine, urea, and two commercial fertilizers, one with and one without amino acids. Grapevines were sprayed at veraison and one week later. There was a good correlation between stilbene concentrations in wine and must, and the concentrations were higher in wine. Treatment with urea favored resveratrol and piceid synthesis by increasing stilbene concentrations in must and wine. Wines from vines treated with phenylalanine had higher concentrations of trans-piceid compared to control wines. However, treatment with proline and commercial nitrogen fertilizers did not affect stilbene concentrations in must and wine samples. Our findings indicate that foliar application of phenylalanine and urea in vineyards could be used to stimulate stilbene synthesis and thus to obtain musts and wines with better health-promoting properties.