Effect of foliar nitrogen and sulphur application on aromatic expression of <em>Vitis vinifera</em> L. cv. Sauvignon blanc

Abstract

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Aims&lt;/strong&gt;: It is well known that vine nitrogen deficiency can negatively impact on aroma in white wines. Soil nitrogen fertilization enhances aroma expression, but it also increases vine vigour and susceptibility to grey rot. The aim of this work was to investigate the impact of foliar nitrogen as well as foliar nitrogen and sulphur applications on aromatic expression, vigour and susceptibility to grey rot of Vitis vinifera L. cv. Sauvignon blanc.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Methods and results&lt;/strong&gt;: The impact of foliar nitrogen (N) and sulphur (S) application on aromatic expression of Vitis vinifera L. cv. Sauvignon blanc has been investigated. On a plot where vine nitrogen status is naturally low and water availability not limiting, foliar nitrogen and sulphur fertilization (10 kg/ha of N and 5 kg/ha of S) increased yeast available nitrogen content. Vine vigour and maturity level of grapes were not modified compared to the control. The wines produced from N+S vines contained more volatile thiols and glutathione. These results were confirmed by a tasting of wines produced with grapes from the experimental plots. Foliar nitrogen fertilization alone (10 kg/ha of N) also increased Sauvignon blanc aromatic expression, but less so than the N + S treatment.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Conclusions&lt;/strong&gt;: Foliar N and foliar N + S applications can enhance aromatic expression in Vitis vinifera L. cv. Sauvignon blanc wines without increasing vine vigour and infestation by grey rot.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Significance and impact of the study&lt;/strong&gt;: Vine nitrogen deficiency can negatively impact on grape aroma potential. Soil nitrogen application can increase vine nitrogen status, but it has several drawbacks: it increases vigour and enhances Botrytis susceptibility. This study shows that foliar N and foliar N + S applications can improve vine nitrogen status and enhance aroma expression in Sauvignon blanc wines without the negative impact on vigour and Botrytis susceptibility. Although this study was carried out on Sauvignon blanc vines, it is likely that foliar N or foliar N + S applications will have similar effects on other grapevine varieties containing volatile thiols (Colombard, Riesling, Petit Manseng and Sémillon).&lt;/p&gt;

Phenylalanine and urea foliar applications to grapevine: Effect on wine phenolic content

“…The latter study showed that foliar application of 2 kg N/ha of urea in a Tempranillo vineyard led to an increase in pH and a reduction of alcoholic strength and total acidity in wine that were even more significant when the dose of urea was greater (4 kg N/ha). Despite this fact, our results are in agreement with those reported by Lacroux et al (2008) who found no differences in these parameters between control and foliar treated samples, although it must be considered that these authors did not mention the dose of nitrogen applied. A positive outcome of our study is the fact that urea application (Ur1) led to an improvement of wine phenolics-related parameters without modifying other important factors such as pH, total acidity or alcoholic strength.…”

Foliar application of urea to “Sauvignon Blanc” and “Merlot” vines: doses and time of application

“…Nitrogen compounds in the grape juice are of great interest in wine-making as they are crucial nutrients for yeast. Indeed, grape juices with high yet balanced amino acid contents result in a greater synthesis of ethyl esters, which are considered to be desirable for wine quality due to their fruity aromas (Lacroux et al 2008). Figures 1, 2, and 3 show the amino acid profiles in grape juice for the different N treatments during this two-year study.…”

A review of the use of biostimulants in the vineyard for improved grape and wine quality: effects on prevention of grapevine diseases

“…To improve the urea effects on grape and wine quality, some studies have been carried out on the addition of sulphur to urea foliar applications. In this way, urea plus sulphur treatment applied to Sauvignon Blanc grapevines provided improved yeast assimilable nitrogen, which increased volatile thiols and glutathione in the wines obtained . In Petit Manseng, this treatment increased the contents of several amino acids in the grapes during the first season of a study .…”