Climatic dependence of the C, N stable isotope ratios and their contents of Guangxi green tea

The stable carbon (C) and nitrogen (N) isotopic ratios and their concentrations in green tea were ascertained across distinct harvest periods within a microclimate setting. The findings revealed statistically significant variations in the δ 15 N (1.67 ± 2.60 ‰ to 4.47 ± 0.68 ‰), N% (4.59 ± 0.38 % to 6.18 ± 0.48 %), and δ 13 C (-27.91 ± 0.65 ‰ to −25.99 ± 0.95 ‰) values among tea samples collected at different harvest periods ( p < 0.05). Typically, these isotopic parameters exhibited an initial depletion indicative of climatic influence, succeeded by an enrichment phase. In contrast, C% demonstrated minimal variation across harvest periods ( p > 0.05), which consistently ranged from 45.93 ± 4.02 % to 47.44 ± 1.01 %. Redundancy analysis and Pearson correlation elucidated the impact of climatic variability on isotopic fractionation within the tea samples. Specifically, δ 15 N values displayed a significant positive correlation with temperature and solar irradiance but a negative correlation with other climatic elements. Conversely, N% exhibited an inverse correlational trend relative to δ 15 N under identical conditions. For δ 13 C, a predominantly negative correlation with climatic factors was observed. The study has delineated the influence of climatic fluctuations on the isotopic composition of tea, offering a valuable theoretical basis for enhancing traceability through stable isotope-based methodologies. • C, N stable isotope ratios and contents in tea were examined. • Isotopic variability was closely depended on climatic conditions. • Microclimatic variability in δ 15 N, N% values was mainly related to temperature. • The δ 13 C values had the strongest relationship with the air quality index.