Hydrogen and Oxygen Isotope Fractionation Effects in Different Organ Tissues of Grapes under Drought Conditions
Yuchen Meng, Baohui Jin, Karyne M. Rogers, Haichao Zhou, Xin Song, Yihui Zhang, Guanghui Lin, Hao Wu
Abstract
A study of different grapevine tissues and organs (root, stem, leaf, fruit) water isotope fractionation models from high-quality wine grapes produced in the Helan Mountains, a key wine-producing area in northwestern China, was undertaken. Results showed that δ 2 H values of local groundwater sources were more negative than rivers and precipitation. Soil water δ 2 H and δ 18 O values were significantly higher than those of other environmental water sources. Water from the soil surface layer (0–30 cm, δ 2 H and δ 18 O values) was more positive than the deeper layer (30–60 cm), indicating that soil water has undergone a positive fractionation effect. δ 2 H and δ 18 O values of tissues and organs from different grape varieties followed a similar pattern but were more negative than the local atmospheric precipitation line (slope between 4.1 to 5.2). The 2 H and 18 O fractionation relationship in grapevine organs was similar, and 18 O has a higher fractionation effect than 2 H. δ 2 H and δ 18 O values showed a strong fractionation effect during the transportation of water to different grape organs (trend of stem > fruit > leaf). This study showed that 18/16 O fractionation in grapes is more likely to occur under drought conditions and provides a theoretical basis to improve traceability accuracy and origin protection of wine production areas.