Influence on grape aroma of nitrogen compounds and elicitors foliar applications in vineyards

Abstract

AIM: The grape volatile compounds determine the wine quality and typicity [1]. Thus, looking for agronomic tools to improve its composition it is of great interest in the sector [2]. The aim of this work was to study the effects of several foliar applications in Garnacha, Tempranillo, and Graciano grapevines in order to enhance their grape volatile composition.

METHODS: The field trial involved the application of two nitrogen compounds, urea (Ur) and phenylalanine (Phe), and two elicitors, methyl jasmonate (MeJ) and a yeast extract (YE), as well as a control (water) in vines of these grape varieties. All treatments were carried out at veraison and one week later. The grapes were collected at their optimal technological maturity. The analysis of grape volatile compounds was carried out by HS-SPME-GC-MS [3].

RESULTS: For Garnacha, most terpenes, and C13 norisoprenoids increased their grape content by applying Ur and Phe, and especially MeJ; there is a large increase in 2-phenylethanol and 2-phenylethanal with the Phe application. For Tempranillo, treatments with Ur and MeJ improved the synthesis of most terpenoids, while the application of Phe was negative for the content of C13 norisoprenoids; and benzenoid compounds increased, in general, with all foliar treatments. For Graciano, a trend to decrease the terpenoids content in grapes with the treatments was observed, especially with Ur and YE; Phe application increased C13 norisoprenoids content, while the application of YE significantly decreased them; this treatment decreased benzyl alcohol and increased 2-phenylethanol contents in grapes.

CONCLUSIONS:

The effect of foliar applications on volatile composition was dependent on the grape variety. The most positive treatments were: Phe and MeJ for Garnacha, Ur and MeJ for Tempranillo, and Phe for Graciano.