[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.