Biofertilizer Foliar Application to the Vineyard: Preliminary Effects On Grape Nitrogen, Aromatic and Phenolic Composition

Abstract This work evaluated, for the first time, the effect of the biofertilizer BlueN® foliar application on grape composition. The experiment included a control (no treatment) and BlueN® foliar application at the onset of flowering. Treatments were arranged in a completely randomized block design with three replicates. Foliar application of BlueN® significantly increased total acidity, the only general parameter of grapes that was altered. It also affected the amino acids profile, likely enhancing nitrogen composition through atmospheric N₂ fixation by Methylobacterium symbioticum . In addition, BlueN® increased terpenoids and C 13 norisoprenoids concentration in musts, suggesting an improvement of their aromatic potential. Additionally, BlueN® modified the phenolic composition of grapes by reducing flavanols, while increasing hydroxycinnamic acids and stilbenes. As the first study to examine the impact of BlueN® on grape composition, these findings highlight its potential as a biostimulant for improving grape composition.