Nitrogen composition in cv. Monastrell berries under climate change: The role of vineyard management

Environmental conditions strongly influence grape amino acid profiles, which are key for fermentation and wine aroma. However, the combined effects of climate-driven warming and reduced rainfall together with vineyard management on berry amino acid composition remain poorly understood under field conditions. This study evaluated the effects of warming (W) and reduced rainfall (RR) on the nitrogen composition of cv. Monastrell berries under conventional (CON) and organic (ORG) vineyard management systems. A field experiment was established in 2023 in a rainfed vineyard (Murcia, SE Spain) using open-top chambers and rain-exclusion shelters to simulate warming and reduced rainfall respectively, with ambient conditions as controls. Individual amino acids and ammonium were analyzed by HPLC at harvest in 2023 and 2024, and nitrogen parameters including total free amino acids (FAN), yeast-assimilable nitrogen (YAN) and precursor aromatic nitrogen (PAN) were determined. ORG management showed higher amino acid concentrations than CON, with increases exceeding 100 % for GABA and proline. In 2023, climate treatments significantly affected 13 amino acids, whereas vineyard management effects and vineyard management × climate interactions were each significant for 4. Warming increased FAN, AAN, YAN and PAN by 25–75 % under ORG and by 111–160 % under CON, while ammonium increased by 96 % and 28 % under ORG and CON, respectively. Reduced rainfall had negligible effects in both years, confirming temperature as the dominant driver. These findings indicate that warming strongly alters grape nitrogen metabolism, whereas organic management mitigates its impact, supporting its role as a sustainable strategy to preserve nitrogen compounds under future climate scenarios.