Foliar Application of an Amino Acid-Enriched Urea Fertilizer on 'Greco' Grapevines at Full Veraison Increases Berry Yeast-Assimilable Nitrogen Content.

Alessandro Mataffo,Antonio Dente,Boris Basile,Giuseppe Colla,Youssef Rouphael,Daniela Strollo,Pasquale Scognamiglio

doi:10.3390/plants9050619

Abstract

Reaching a sufficient yeast assimilable nitrogen (YAN) content in berries at harvest is considered a main viticultural goal for wine-making, because low YANs can slow down must fermentation and have negative effects on wine sensory attributes. For this reason, many attempts have been made to define correct fertilization strategies to stimulate YAN accumulation in the berries. Foliar application of amino acid-enriched urea fertilizer is considered a promising environmentally friendly strategy for improving the yield and nutrient efficiency of plants. The aim of this two-year research was to study the effects of two fertilizers based on urea enriched with amino acids applied at low doses in diverse phenological stages on berry YAN concentration in ‘Greco’ grapevines. The results of this study indicate that amino acid-enriched urea fertilizers induced an increase in YANs in the ‘Greco’ berries at harvest, but only when the application was undertaken at full veraison. Foliar applications applied at veraison onset or post-veraison appeared to be ineffective. In addition, the fertilizers enhanced YAN accumulation in the berry without modifying the other composition parameters measured in this study (total soluble solids, titratable acidity, pH and malic acid). Therefore, the results of our study suggest that foliar application of urea fertilizers enriched with amino acids is an effective strategy to increase yeast-assimilable nitrogen concentration in grapevine berries at harvest.

Highlights

Yeast assimilable nitrogen (YAN) content is a key factor in the fermentation kinetics of musts [1].an insufficient must YAN concentration was reported to slow down fermentation and to cause the undesired presence of thiols and higher alcohols in the wine [1,2] with detrimental alteration of the wine aromatic profile [3]
Canoura et al [21] reported that foliar N fertilization is more effective in increasing berry YAN concentration compared to soil drench fertilization, but the effectiveness of foliar fertilization depends on the timing of application [22]
Foliar application of fertilizers based on urea enriched with amino acids induced a significant increase of YAN concentration in the berries of ‘Greco’ grapevines, but the effectiveness of these products were dependent on the phenological stage of application

Summary

Introduction

An insufficient must YAN concentration was reported to slow down fermentation and to cause the undesired presence of thiols and higher alcohols in the wine [1,2] with detrimental alteration of the wine aromatic profile (i.e., formation of unpleasant off-flavors) [3]. To solve such deficiency, nitrogen (N) is usually added to the must, but this kind of supplement represents a significant cost for the wineries and affects their operational logistics. Protein hydrolysates (PH) which are a mixture of peptides and free amino acids, are considered a useful tool to improve plant performance and

Methods

Results

Discussion

Conclusion