Analysis The Fluorescence Spectrum Of Laser-induced Chlorophyll

Gaining agronomy parameter and nutrition information early is very important method for diagnosis of flower, vegetables and trees.And it is also important for managing the culture of plants properly, analysising the influencing factor of environment,preventing and controlling growth failure effectively, managing water and fertilizer as required, promoting productive efficiency of agriculture. In the early time,it is very usually to use of visual and other subjective experience or chemical analysis method to determine the health status of plants. Visual method can not be achieved Digital Management, Chemical analysis method needs the destruction of plants in vivo, needs plant samples, needs the use of chemicals, crushing, separation and pre-processing, etc, needs special technical to complete the project and the whole is process cumbersome and inefficient.In recent years, with the development of spectroscopic techniques, a growing number of experts and academics applied spectral analysis techniques to the examination of growth information of plants intact. Infrared spectrum, spectrum of reflection and fluorescence spectrum are most commonly used.But only fluorescence spectrum is joined to photosynthesis closely. laser-induced fluorescence can make spectrum be clearer. So The growth information of plant can be express more precisely.Cucumber is one of China's High-yielding vegetables, and it has a higher demand for water and nitrogen fertilizer .So we chose cucumber to do the experiment and we designed the experimental program whith is 2 factors including water and nitrogen fertilizer 4 level cross-experiment, repeat 40 times. In the experiment, we measured leaf moisture content, Relative chlorophyll content, soil moisture, leaf nitrogen content, Kinetic curves of fluorescence parameters Fv/Fm, leaf photosynthetic rate and the laser-induced chlorophyll fluorescence spectrometry. The following are the results of our analysis⑴We analyzed the changes of intensity and wavelength of the two peaks and a trough of fluorescence spectra at different levels of water and nitrogen fertilizer, and we and analyzed the result of the impact caused by phyllotaxy. We found that fluorescence intensity ratio of two peaks has a sensitive change in different levels of water and nitrogen fertilizer .The intensity of fluorescence peak has a great change in the same leaf, so it can not be used to judge the content of the leaves. The wavelengths of two peaks of the Fluorescence spectra are 685nm and 734nm, there is only a little irregular change which is more little than 5nm, in different leaves. Therefore, in quantitative analysis, we established the regression equation between intensity ratio of two peaks of the fluorescence spectrum and leaf moisture content and relative content of chlorophyll.⑵We analyzed the relationship between relative content of chlorophyll and nitrogen application rate. For four nitrogen levels Papers mentioned in this paper, relative content of chlorophyll and nitrogen content of leaf have a rise with the increase of the amount of nitrogen fertilizer application. We found that there is different degree of sensitivity in Relative content of chlorophyll in leaves and nitrogen content in different phyllotaxy. We also found that relative content of chlorophyll has a rise with the increase of intensity ratio of right and left peak of Fluorescence spectrometry. We made a quantitative analysis about the relationship between the intensity ratio of left and right peak of Fluorescence spectrometry and the relative content of chlorophyll through the No. 3 and No. 4 fully extended leaves. The regression equation is y = 0. 1296×e0.04035x and the corresponding correlation coefficient is R 2 =0.5408.⑶We analyzed the relationship between Leaf moisture and Soil moisture, and the relationship between Leaf moisture and Watering volume. When the scope of soil moisture is 21.0%~21.9%, the moisture content of leaves is Maximum. We analyzed the impact of phyllotaxy on the degree of sensitivity about leaf moisture and watering volume .We found that the second and third leaves of cucumber plants are the most sensitive about watering volume. We analyzed the relationship between Leaf moisture and fluorescence spectroscopy, and found that leaf moisture content has a decline with the increase of intensity ratio of right and left peak of Fluorescence spectrometry, We made a quantitative analysis about the relationship between the intensity ratio of left and right peak of Fluorescence spectrometry and the Leaf moisture content through the No. 2and No. 3 fully extended leaves. The regression equation is y = 10. 6e?3.15x, and the corresponding correlation coefficient is R 2 =0.2508.⑷We used Fv/Fm one of the parameter of Fluorescence kinetic curve and the experimental results to demonstrate the rationality one of the manner that we applied to analyse Fluorescence spectroscopy.