Sustainable Vineyard Management with On-Field UV-C Irradiation: Impacts of Supplementary Applications on Grape Composition and Secondary Metabolites

Research for sustainable viticulture practices has fostered interest in ultraviolet-C (UV-C) radiation as non-chemical tool for vineyard pathogen control; however, little information is available on their potential elicitation of berry metabolites. This two-year study investigated the impact of supplementary in-field UV-C applications, in addition to the vineyard sanitary protocols, on berry composition in Cabernet Sauvignon grapevines. In both experimental years, vegetative, yield, and berry technological parameters were determined at harvest, but they were not altered by UV-C treatments. Significantly higher concentrations of berry secondary metabolites were measured at harvest trough GC-MS and HPLC. UV-C treated vines had higher berry anthocyanins, particularly tri-hydroxylated forms (malvidin, delphinidin, petunidin), and flavonol concentrations (quercetin, myricetin derivatives), improving the potential for wine color stability and copigmentation. Glycosylated berry aroma compounds were also increased in UV-C vines, particularly some monoterpenes (geraniol, nerol, citronellol), C₁₃-norisoprenoids (β-damascenone, β-ionone, 3-oxo-α-ionol), and volatile phenols (eugenol, 4-vinyl-guaiacol). These results highlighted the potential of UV-C in-field applications, in addition to pest management control, to increase grape quality traits by modulating berry phenolic and aroma profile without affecting productivity.