Preharvest salicylic acid application improves the amino acid content and volatile profile in Vitis vinifera L. cv. Chardonnay during development

Nitrogen is an important component that affects grapevine growth and the formation of flavor-associated volatile chemicals in grape berries. Dynamic changes in amino acids and aroma compounds in Chardonnay grape berry preharvest treated with different doses of salicylic acid (SA) at onset and one week later of veraison stage were evaluated. Exogenous 1- or 3-mM SA application significantly increased the content of total soluble solid and titratable acid in grapes, while 5 mM SA tended to decrease their levels. Compared with the control, the concentration of yeast assimilable nitrogen were 9.3% and 14.6% higher in 3 mM SA-treated grapes in 2021 and 2022, respectively. Preharvest 3 mM SA treatment efficiently enhanced the accumulation of nine amino acids, including tryptophan, phenylalanine, tyrosine, aspartic acid, lysine, asparagine, valine, isoleucine and histidine, as well as the concentration of total amino acid with and without proline in the two grape vintages. Higher concentrations of primary phenylalanine-derivatives and terpenoids and lower levels of C6 compounds in grapes treated with 3 mM SA were observed during the 2021-2022 season. Overall, SA improved the quality of wine grape in a dose dependent manner, while the response of berries to SA treatment also showed effects of the vintage.