Changes in Physiological Indices, Amino Acids, and Volatile Compounds in Vitis vinifera L. cv. Pinot Noir under UV-B Radiation and Water Deficit Conditions.

UV-B radiation and water deficit can challenge Pinot noir growth and fruit quality. The aim of this work is to determine the effects of UV-B and water deficit on the physiological indices, amino acids, and volatile compounds of Pinot noir vine and fruit. The results showed that both individual and combined treatments caused a decrease in the leaf SPAD, with the largest amplitude being observed in the combined treatment. Water deficit also decreased the leaf water potential and increased the juice δ 13 C‱ at harvest, which was the opposite of the latter under UV-B radiation. Interestingly, most of the physiological indices under combined stresses did not show significant changes compared with that under no UV-B and the well-watered control treatment. Moreover, the concentrations of amino acids and volatile compounds in the berries were determined at harvest. The amino acid contents were significantly increased by the combined treatment, particularly proline (Pro), aspartate (Arg), alanine (Ala), and threonine (Thr). There were slight increases in volatile compounds. This research substantially contributed to improve our scientific understanding of UV-B and water deficit responses in an important commercial species. In addition, it highlighted some future research to produce high-quality wines with the anticipated specific characteristics.