The Characteristics Of Carbon And Nitrogen Stable Isotope Ratio In Rice Research

The control of food security becomes more and more important going with global food markets development. Food origin traceability system provides an approach for protecting regional brand, ensuring fair competition, promoting consumer confidence, and preventing diffusing of food pathogen. Analytical techniques used for determining food origin include fluorescence spectroscopy, atomic spectroscopy, gas chromatography, liquid chromatography, Biotechnology, isotope ratio mass spectrometry. Stable isotopic analysis is an effective technology for food origin assessment, which generally involves various foods such as wine, beverage, dairy, meat, grain and so on. Because the determination of stable isotope ratio is barely influenced by changed experimental conditions, so this method has high precision, high accuracy, and no pollution.Isotopic compositions of plants can be effected by many factors, such as their species, natural environment and human activities. Carbon in plants related to photosynthetic pathways. Based on the different kinds of photosynthetic,δ13C values in plants are different.δ15N values of plants are mainly influenced by soil nitrogen. N isotopes mainly are affected by agricultural cultivation. Besides,δ15N of plants can be increased if organic fertilizer is used, while it can be reduced if chemical fertilizer is used. Furthermore,δ15N of plants relate to temperature, rain water and nitrogen in leaf.Stable isotope ratio of carbon and nitrogen were studied in polished rice which were collected from Heilongjiang(3), Liaoning(3), Henan(1), Jiangsu(1),Hunan(1), Hainan(1), then these samples were analyzed by elemental analyzer/isotope ratio mass spectrometry (EA/IRMS). The results showed that δ13C values of10rice samples ranged from-26.0‰to-28.3‰and the average was-27.0%o and most of δ13C occurs from-26.0%o to-27.3‰.δ15N values of samples ranged from1.1‰to4.1‰and the average was2.4%o and most of δ15N occurs from1.0‰to3.0‰. The fluctuation of δ15N values was more remarkable than δ13C.The similarity of stable isotope ratio of carbon and nitrogen between Chinese and foreign rice were discussed in terms of Q-type hierarchical cluster analysis. The hierarchical cluster result showed that when using δ13C and δ15N together as variables, American and Chinese rice samples can be separated clearly. American samples were divided into two clusters and Chinese ones can be divided into another two clusters. Japanese and Chinese rice samples can be separated clearly. Chinese samples were divided into one cluster and Japanese ones were divided into three clusters. Moreover, Chinese and American or Japanese samples cannot be separated by using δ13C or δ15N as the independent variables. In addition, the cluster results were influenced by the number of variables. The cluster results were reflected more distinct using commonly δ13C and δ15N as the variables, rather than using813C or δ15N as the independent variables, respectively.