Effects of elevated temperature and shaded UV-B radiation exclusion on berry biochemical composition in four grape (Vitis vinifera L.) cultivars with distinct anthocyanin profiles

The biochemical composition and quality of grape berries are influenced by environmental factors and exhibit significant variability among cultivars. The objective of this study was to quantify the differential sensitivities of grape cultivars with distinct anthocyanin profiles to elevated temperature and shaded UV-B radiation. Over two consecutive vintages, the clusters of four grape cultivars, including Gewurztraminer, Pinot Gris, Pinot Noir, and Tempranillo, were subjected to coverage with plastic films either shielding 99.9 % or 38 % of UV-B (hereafter referred as Cover-UVB and Cover+UVB, respectively), in comparison with clusters not covered (CK). Results showed that both Cover+UVB and Cover-UVB elevated cluster microclimate temperatures compared to CK. The elevated temperature under both Cover+UVB and Cover-UVB reduced malic acid, while its impact on anthocyanins was genotype-dependent. The effects of elevated temperature on berry composition were overweighed the effects of the different UV-B intensities tested in our study condition.