Variation Law And Fractionation Characteristics Of Hydrogen And Oxygen Isotope In Korla Fragrant Pear During Growth Period

Korla Fragrant Pear is a mutually recognized geographical indication product between China and Europe.Stable isotope fingerprint technology is one of the technical means used in the identification of the origin of agricultural products at home and abroad.Hydrogen（H）and oxygen（o）stable isotopes are the most commonly used isotopes in the authenticity identification of agricultural products.The stable isotopic composition of H and O in its fruit reflects the material exchange process between the whole growth period and the ecological environment from fruit setting to maturity.In this process,the fruit will be fractionated with the changes of eco-environmental factors（temperature difference between day and night,sunshine time,rainfall,and even extreme weather）in the whole growth period.Its fractionation mechanism determines whether the stable isotopes of H and O can become an accurate,stable and reliable origin traceability index,which is an urgent scientific problem to be studied.By analyzing the temporal and spatial distribution of H and O stable isotope ratio in the fruit growth period of Korla Fragrant Pear,the variation law and fractionation characteristics of H and O stable isotopes affected by ecological factors were discussed,so as to provide reference for the authenticity identification of Korla Fragrant Pear.In this study,Korla Fragrant Pear from different producing areas was taken as the research object.The fruit samples 60～150 days（d）after flowering in 2020 and 2021 were collected.The fruit water was extracted by vacuum condensation extraction method.The H and O isotopes in the fruit water were measured by high temperature pyrolysis isotope ratio mass spectrometry（HT-IRMS）.Combined with analysis of variance,correlation analysis and redundancy analysis（RDA）,The main conclusions of this paper are as follows:1:Theδ²H andδ¹⁸O of the fruit water of Korla fragrant pear during the growth period have obvious temporal and spatial variation characteristics.With the continuous ripening of the fruit during the growth period,the H and O stable isotopes of the fruit water of Korla fragrant pear in the three producing areas have an obvious depletion trend.2:In the early stage of fruit setting,the H and O isotopes of fruit water showed obvious enrichment ability of ²H and ¹⁸O.With the fruit of Korla fragrant pear continues to mature during the growth period,the water isotopes of the fruit tend to be in equilibrium,the enrichment ability of the fruit water to soil water ²H and ¹⁸O gradually weakens,and theδ²H andδ¹⁸O values of the fruit water are closer to its water source.3:The H and O isotopes of Korla Fragrant Pear Fruits in Korla City and Aksu City show their own fingerprint characteristics.The mature Korla Fragrant Pear can be effectively distinguished by the fingerprint characteristics of H and O stable isotopes.4:In the interaction relationship between the ecological environment factors of the three production areas of Korla,Aksu,and Jiuquan in Gansu and theδ²H andδ¹⁸O characteristics of the fragrant pears in the production areas during the growth period,the changes in the temperature and theδ²H andδ¹⁸O of the irrigation water sources in the production areas are the most important factors affecting the growth period of the fragrant pear.The main reason for the change of fruit waterδ²H andδ¹⁸O is that there is a good correlation between the irrigation water sourceδ²H andδ¹⁸O and the fruit waterδ²H andδ¹⁸O in the late growth period of fragrant pear.