[A study of the diversity of different geographical populations of Emmenopterys henryi using FTIR based on principal component analysis and cluster analysis].

Emmenopterys henryi, an endemic species in China, has been one of the grade II national key conservation rare and endangered plants. The spectra of stem and leaf of Emmenopterys henryi sampling from seven different geographical populations were determined by Fourier transform infrared (FTIR) spectrometry with OMNI-sampler directly, fast and accurately. A positioning technology of OMNIC E.S.P.5.1 intelligent software and ATR correction was used. It was scanned for the background before the determination of every example. The peak value and absorbance were ascertained using a method of baseline correction in infrared spectra. Based on the indices of wave number-absorbance from 721 to 3366 cm(-1), the differences of these infrared spectra were compared by the methods of principal component analysis (PCA) and cluster analysis. Results showed that there were some differences in FTIR spectra between stem and leaf of Emmenopterys henryi, so it was better to study the diversity of different geographical populations through using the leaf, for which the distance coefficient of clustering analysis plot and the position relationship of principal component analysis three-dimensional plot of the seven populations were bigger. Being far away from others populations, the infrared spectra of Emmenopterys henryi in Dapan Mountain and Gutian mountain had special characteristics, indicating significant diversity. At the same time, the infrared spectra of Jiulong Mountain, Wuyan Mountain and Songyang populations had their own characteristics. There were no significant difference in the position relationship of three-dimensional plot and distance coefficient of clustering analysis plot, showing that the chemical compositions of these three populations were of little difference, and the diversity differentiation was not remarkable. However, there were some significant differences in populations' diversity between Fengyang Mountain and Wencheng. It was indicated that the chemical composition of Emmenopterys henryi was affected by the special geographic positions and environment conditions. In a word, the remarkable differences in the chemical compositions of Emmenopterys henryi populations were consistent with their geographic distance far and near. The results also showed that there was good correspondence between the position relationship of PCA three-dimensional plot and distance coefficient of clustering analysis plot of the samples based on the indices of wave number-absorbance of FTIR and their geographic distance relationship. Therefore, FTIR can be used widely for studying and protecting the rare and endangered plants. It is not only provides the theoretic base of community ecology and ecosystem ecology of Emmenopterys henryi, but also has important theory and realistic meaning for exploring the mechanism of species endangerment, protecting and proliferating the populations of Emmenopterys henryi.

[FTIR spectra of endangered plants Ulmus elongata and its correlation to soil nitrogen].

Ulmus elongata, an endemic species in China, is one of the grade II national key conservation rare and endangered plants. The spectra of root, stem, skin and leaf of Ulmus elongata sampled from eight different sites were determined by Fourier transform infrared (FTIR) spectrometry with OMNI-sampler directly, fast and accurately. A positioning technology of OMNIC E.S.P. 5.1 intelligent software and ATR correction was used. The background was scanned before the determination of every example. The peak value and absorbance were ascertained using a method of baseline correction in infrared spectra, and then the relativity between absorption peaks of the spectra and the soil nitrogen was analyzed. Results from the comparison of the spectra showed some differences in their FTIR spectra among root, stem, skin and leaf of Ulmus elongata from the same plant. The coefficients of correlation between chemical composition of this four different organs of Ulmus elongata and soil nitrogen were positive in different degrees. There was the significantly positive correlation between chemical composition of stem and total nitrogen (p < 0.05). When the wave-number was 3 365 cm(-1), there was a significantly positive correlation between chemical composition of skin and total nitrogen, and a low correlation between root and leave chemical composition and total nitrogen. There was also a certain extent correlation between chemical composition of this four different organs of Ulmus elongata and soil available nitrogen, but the coefficients of correlation was smaller, and the level of the statistic significance was not significant (p > 0.05). It was showed that the change in soil total nitrogen has some influence on chemical composition of different organs of Ulmus elongata, but the degree of available nitrogen was very smaller. The linear correlation between soil total nitrogen and organs chemical composition of Ulmus elongate, not only provided the theoretic basis for plant nutriology and nutrient ecology of Ulmus elongate, but also proved that the plants and soil were inseparable. The results also showed that FTIR can be used widely for analysis of the correlation between chemical composition of endangered plants and soil physical and chemical properties in the future, and indicated that the new method has practicability and reliability to a certain degree.