茶树不同叶位碳氮氢氧稳定同位素分布及变化特征

为探究茶树不同叶位的传统稳定同位素分布及其随时间的变化特征,本研究以龙井43#品种茶树为研究对象,采用元素分析-同位素比值质谱仪(EA-IRMS)对不同叶位叶片的碳同位素(δ¹³C)、氮同位素(δ¹⁵N)、氢同位素(δ²H)和氧同位素(δ¹⁸O)进行分析。结果表明,随叶位自上向下递增,叶片中δ¹³C、 δ¹⁵N和δ²H显著贫化,而δ¹⁸O呈现相对较弱的贫化,且第2~第5叶位叶片的同位素比值最高(21.0‰~25.0‰),相邻叶位的同位素分馏系数差异不大。此外,随着采样时间的变化和环境气候影响,前三叶位叶片的δ¹³C和δ¹⁵N总体呈现富集特征,而δ²H和δ¹⁸O出现先贫化后富集的变化特征。本研究结果为探究茶树不同叶位茶叶传统稳定同位素的分布提供了数据支撑,也为研究茶叶分馏机制和数据库构建奠定了基础。

Leaf Position Distribution and Variation of Stable Carbon,Nitrogen, Hydrogen and Oxygen Isotopes in Camellia sinensis

To study the distribution of traditional stable isotopes in different leaf positions of Camellia sinensis and their changing characteristics with time, the δ¹³C, δ¹⁵N, δ²H and δ¹⁸O of leaves at different leaf positions in Longjing 43# were analyzed by elemental analysis-isotope ratio mass spectrometer (EA-IRMS). The results showed that δ¹³C, δ¹⁵N, and δ²H of leaves were significantly depleted from top to bottom of leaf position. But δ¹⁸O was not significant depleted compared with other three isotopes, which showed the highest (21.0‰~25.0‰) from second to fifth leaf position. There was no significant difference in isotopic fractionation coefficients between adjacent leaf positions. Affected by the sampling time and environmental climate, δ¹³C, δ¹⁵N of the former 3 position leaves became enriched during our research date, while δ²H and δ¹⁸O were depleted and then enriched. This study would provide data support for exploring distribution of traditional stable isotopes in leaves at different positions and establish a foundation for studying of fractionation mechanism and database construction.