1. Effect of different foliar nitrogen applications on the must amino acids and glutathione composition in Cabernet Sauvignon vineyard
Teresa Garde-Cerdána, Ana Gonzalo-Diagoa, Gastón Gutiérrez-Gamboab, Yerko Moreno-Simunovicb, Ana M. Martínez-Gilb
aInstituto de Ciencias de la Vid y del Vino (Gobierno de La Rioja-CSIC-Universidad de La Rioja). Carretera de Burgos Km. 6. Finca La Grajera Logroño, Spain.
bCentro Tecnológico de la Vid y el Vino, Facultad de Ciencias Agrarias, Universidad de Talca, Av. Lircay S/N, Talca, Chile. Tel: *
Introduction
The climate change in warmer areas, has led to a change in the organoleptic profile of Cabernet Sauvignon grapes, so improving grape quality potential is an important challenge for the wine production. Amino acids play an essential role as nitrogen sources for yeast. For its part, the Glutathione acts as an antioxidant, protecting anthocyanins from oxidation and exerts a protective effect in wine volatile compounds1. Previous studies have shown that urea foliar application affects grape and wine composition2. However , there is already a lack of information relating to the impact of nitrogen application, and more concretely, amino acid application in the vineyard, on the must amino acid and glutathione composition.
The aim of this study was to evaluate the influence of foliar application of arginine, urea, urea + sulphur and two commercial nitrogen fertilizers on the must amino acid and glutathione composition in a Cabernet Sauvignon vineyard.
Materials and methods
Results and discussion
Oenological parameters and nitrogen fractions
None of the treatments affected technological maturity. However, grape phenolic maturity was affected by Arg treatment, increasing the concentration of easily extractable anthocyanins (mg/l), total anthocyanin (mg/l) and total polyphenol index.
Grape amino acid composition
The amino acids found in higher concentrations were Pro, Arg, GABA, Glu, and Ala while the found in lower concentration were Gly, Met, Trp, Orn and Lys.
BA application increased the concentration of Arg in 44%, this amino acid is one of the best source of nitrogen for yeast.
None of the treatments applied modified the content of GABA.
Glu was increased with Ur+S and NT applications while decreased with Ur treatment, this amino acid is a key component of central nitrogen metabolism and are preferred nitrogen source for yeasts.
Alanine also constitutes a good source of nitrogen for yeast and its content is correlated with volatiles compounds and yeast metabolites such as 2-ketopropionic acid, acetaldehyde and ethanol3. BA increased the alanine concentrations, showing an increase of 75%. However, the Ur treatment decreased it a 39%, all respect to control samples.
Glutathione content in musts
NT treatment increased considerably the glutathione content in grapes, folding 16 times the control value, followed by Arg and BA, in which the concentration increased more than 10 times. No significant effects were found in Ur and Ur+S applications with respect to the control samples
PCA shows that Ur+S, NT and BA treatments were correlated with the most amino acids.
The study was conducted in Cabernet Sauvignon vines located in Pencahue (Región del Maule, Chile), during growing season.
Five treatments were carried out using several nitrogen sources: urea (Ur), urea plus sulphur (Ur+S), and arginine (Arg), and two commercial products, Nutrimyr Thiols (NT), and Basfoliar Algae (BA) .
2 kg N/ha dose were applied divided at the varaison and two weeks later. 200 ml of each formulation was applied evenly per plant.
Analysis of amino acids and glutathione compounds in grapes was performed by HPLC-DAD.
Conclusion
The present study shows the first results about foliar nitrogen applications in high proline accumulating varieties such as Cabernet Sauvignon, so it could have oenological interest because contributes to gain knowledge about the response of amino acids and gluthatione content to different nitrogen foliar applications. a
Figure 1. Glutathione (GSH) concentration (mg/l) in musts. All parameters are given with the standard deviation (n = 3). Different letters indicate significant differences (p ≤ 0.05) between treatments.
REFERENCES
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Lacroux, F., Tregoat, O., Van Leeuwen, C., Pons, A., Tominaga, T., Lavigne-Cruège, V., & Dubourdieu, D. (2008). Effect of foliar nitrogen and sulphur application on aromatic expression of Vitis vinifera L. cv. Sauvignon blanc. Journal International des Sciences de la Vigne et du Vin, 42,
Bell, S.-J., & Henschke, P.A. (2005). Implications of nitrogen nutrition for grapes, fermentation and wine. Australian Journal of Grape and Wine Research, 11, 242–295. Ur BA
Ur+S
Ctr
Arg NT
ACKNOWLEDGEMENTS
San Pedro’s commercial vineyard, for their collaboration in this research. Magister en Horticultura with the proyect TAL1201 (RCE ). Gobierno de La Rioja under the project R T. G.-C. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)-Gobierno de La Rioja and European Social Fund for her doctoral contract
Figure 2. Principal components analysis (PCA) performed with all amino acids (mg/l) and glutathione (mg/l) in Cabernet Sauvignon samples