Research On Both Characteristics Of DF And Its Applications In Environment And Agriculture

Delayed fluorescence associated with plant metabolism and photosynthesis. The characteristics and its applications in the environmental inspection and agriculture are presented in the thesis. Firstly, the primary common sense on delayed fluorescence and research progress were introduced in the chapter one, and then the basic concepts and principles of chemiluminescence and bioluminescence were represented in the chapter two. Meanwhile, the concept and theory of delayed fluorescence are stated in detail.In the chapter three, the mechanism for delayed fluorescence origin is theoretically stimulated. The decay kinetic of DF, depends on the backward transport electron and oxidized state P680+, can be well fitted by poly-exponent. The relative fast component of DF originates from the Z+P680QA~ states, generated during the previous period of the sample illumination. On the other hand, the slow component of DF is ascribed to the state QB-the next electron carrier of deoxidized side in PS II. Furthermore, we testified that the third component with lifetime much greater than the time of the registration period (which is presented as a constant), is corresponds to therecombination of P680+and the backward transport electron from PS I .Based on the chapter three, the mechanism of 730nm component appeared in theDF spectrum of chloroplast was studied with different spectral analysis methods. Experimental results of the delayed fluorescence spectrum at different chloroplast concentration showed that the apexes at 685nm and 730nm ascend with chloroplast concentration increased while the concentration is relative low; the peak value at 685 nm reaches a maximum when the concentration is 7.8 ug/ml, however, the apex at 730nm is still increasing. The peak value at 730nm finally reaches a maximum at chloroplast concentration 31.2 u,g/ml while the apex at 685nm has apparently decreased. The results of absorption spectrum showed that the ratios of A685 to A730 are almost a constant during the increased process of chloroplast concentration.Furthermore, the excitation spectrum for 730nm fluorescence shows that the 685nm light has high excitation efficiency. Above experimental results indicated that the 730nm component of DF spectrum is the fluorescence of chlorophyll a in PS I reaction center excited by 685 nm DF. Meanwhile, this conclusion is further verified by the invariability of DF spectrum at different delay time (1-9).In the chapter five, the correlation between the intensity of delayed fluorescence and the intactness and function of chloroplast were studied, and the results show that the changes in DF intensity of green plants can truly reflect the changes of intactness and functions of chloroplast. The pollution effects of the plant leaves treated with acid material can be detected quantitatively by means of DF. The technique would likely to be applied as a practiced field application with easier operation than chlorophyll fluorescence technique. Thus, we conclude that delayed fluorescence is an excellent indicator for evaluating the extent of environment stress on plant. The changes in delayed light emission intensity may provide a new approach for the detection of environment pollution and its impact on the ecosystem.The relationship between the capability for photosynthesis and the DF is investigated in the chapter six. Compared with common methods for measuring the photosynthesis rate based on consumption of CO2, the technique in this thesis can be used to quantify the plant photosynthesis capability with less interferences of the environment. We thus conclude that DF is an excellent indicator for evaluating plant photosynthesis ability under its biological status. Therefore, the biosensor will be likely to provide a new approach for measuring the plant photosynthesis capability in the future.At the end of the paper, we have prospected the biological and medical application of delayed fluorescence. Finally, a full summary of the thesis is given.