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Polysaccharides are the main group of macromolecules in wines. Climate change is a major problem for viticulturists as it leads to the production of unbalanced grapes. This is attributed to a mismatch between the technological maturity and phenolic maturity of grapes, which can negatively impact the production of high quality wines. To mitigate this effect, biostimulants can be applied to grapevines. For the first time in the literature, this work studied the foliar application of methyl jasmonate plus urea (MeJ + Ur) on the vineyard and its effect on the monosaccharide and polysaccharide composition of Tempranillo grapes and wines over two consecutive seasons. To achieve this, the extraction and precipitation of polysaccharides was conducted, and the identification and quantitation of monosaccharides was performed via GC–MS. The effect of MeJ + Ur foliar treatment in both the grapes and wines was season-dependent. The MeJ + Ur treatment had a slight impact on the monosaccharide composition of the grapes and also demonstrated a small effect on the wines. Multifactor and discriminant analysis revealed that the season had a greater influence on the monosaccharide and polysaccharide composition of grapes and wines compared to the influence of MeJ + Ur treatment. Interestingly, the MeJ + Ur-treated wines exhibited a higher sensory evaluation than the control wines in the second vintage. To gain further insights into the effect of MeJ + Ur foliar application on the monosaccharide and polysaccharide composition of grapes and wines, further investigations should be conducted.

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Foliar application of biostimulants (including resistance inducers or elicitors) in the vineyard has become an interesting strategy to prevent plant diseases and improve grape quality on the grapevine. This also represents a partial alternative to soil fertilisation, avoiding some of the negative effects to the environment from leaching of nutrients into the groundwater. The foliar applications that most promote the synthesis of secondary metabolites in grape berries are treatments with nitrogen, elicitors, other biostimulants, and waste from the agricultural industry. However, the impact of their use in the vineyard depends on a number of conditions, including mainly the type of compound, application rate, timing and number of applications, and cultivar. This review thus summarises the influence of biostimulants as foliar applications to grapevines on grape amino acids and their phenolic and volatile concentrations, to define the most important factors in their effectiveness. © 2018 Society of Chemical Industry.

Nitrogen affects grapevine growth and also yeast metabolism, which have a direct influence on fermentation kinetics and the formation of different volatile compounds. Throughout the grapevine cycle, soil nitrogen availability and grape nitrogen composition can vary because of different factors. Nitrogen foliar applications can contribute toward enhancing grapevine nitrogen status and minimize the problem of leaching that traditional nitrogen-soil applications can provoke. The present study aimed to evaluate the influence of urea foliar applications on grapevine nitrogen status and grape amino acid content. Accordingly, two different doses of urea were applied over the leaves of a 'Tempranillo' vineyard.The highest urea doses affected nitrogen content on blade leaf tissues after veraison. Must amino acid profiles were modified by urea application and some of the compounds increased their concentrations. The effect of year on the increase of must total amino acid concentrations was more important than the effect of the doses applied.Urea foliar applications can be an interesting tool for decreasing grapevine nitrogen deficiencies. This method of nitrogen implementation in the vineyard could avoid sluggish fermentation problems during winemaking, enhance must nitrogen composition, and contribute to improving wine quality. © 2016 Society of Chemical Industry.