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Reasearch On Laser-induced Chlorophyll Fluorescence Detection Technology

Posted on:2020-12-19Degree:MasterType:Thesis
Country:ChinaCandidate:M J FuFull Text:PDF
GTID:2370330578959941Subject:Physics
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Photosynthesis can directly reflect the growth state of plants.Monitoring the growth of plants can prevent and reduce the effects of drought stress,nitrogen stress,pest and disease stress,etc.It is of great significance to guarantee efficient and high-quality production,and it can increase the yield of plants,such as trees and crops.However,the current judgment on the health status of plants mostly depends on the visual inspection of the experience or chemical analysis methods.The detection process is cumbersome and inefficient,and it is impossible to make early predictions on the stress state of plants.The chlorophyll fluorescence is a non-destructive technique with potential to reflect light energy absorption,potential maximum photosynthetic capacity,photosynthetic efficiency,photochemical quenching,non-photochemical quenching,photosynthetically active radiation,CO2 fixation,excitation energy transfer,quantum efficiency of Photosystem II and other photosynthesis processes.Therefore,chlorophyll fluorescence analysis has been developed into a kind of simple,fast,non-destructive and accurate technique in photosynthesis research.Chlorophyll fluorescence as a tool for evaluation of drought,nitrogen,temperature,lead pollution and salt stress in plants.Chlorophyll fluorescence has been recently used to estimate gross primary productivity?GPP?,chlorophyll content,effect of light quality on growth and some other ecological parameters.At present,depending on the different of light source,the detection technology can be divided into laser-induced chlorophyll fluorescence technology and sun-induced chlorophyll fluorescence technology.The laser-induced fluorescence technology can provide more information and a clear physical meaning because of the high intensity and high brightness of the laser,and it is not affected by the external environment.In this paper,a detection method was present for evaluating chlorophyll content based on laser-induced chlorophyll fluorescence spectrometry.The spectroscopy system was developed by assembling a laser diode with the center wavelength of 456 nm,a USB4000grating spectrometer,an optical fiber,a long-pass light filter in the 5421 100 nm spectral range.The spectrometer embedded in the spectroscopy system is connected to a PC through a USB2.0 connection.The system was capable of collecting real-time and non-destructive measurements.The instruments'optical design,data collection and processing were reported and discussed.A comparative analysis of chlorophyll fluorescence using different light sources was discussed by 405 nm LD,456 nm LD,532nm LD and 660 nm LD.Farearea was an indicator for evaluating the chlorophyll fluorescence.The systematic errors and stability were analyzed.Chlorophyll fluorescence spectra of different plants were done for the purpose of qualitatively analyzed.Quantitative analysis was done by spectrophotometry.We present the analysis of correlation between the chlorophyll fluorescence(Farea)and the chlorophyll?Chl?content of cucumber leaves.Farearea was tightly related with Chla content?R=0.89,p<0.01?,and the fitting equation was y=1.37x-0.32?R2=0.78?.Farearea was tightly related with Chlb content?R=0.91,p<0.01?,and the fitting equation was y=0.59x+0.33?R2=0.82?.Farearea was tightly related with Chl?a+b?content?R=0.90,p<0.01?,and the fitting equation was y=1.97x+0.01?R2=0.80?.The relative error of chlorophyll content was discussed.This paper verifies the feasibility of using laser-induced chlorophyll fluorescence detection technology for chlorophyll content determination.Further promote the application of laser-induced chlorophyll fluorescence technology in non-destructive measurement of plants.It is of guiding significance for using chlorophyll fluorescence Farea to evaluate photosynthesis.
Keywords/Search Tags:Chlorophyll Fluorescence, Laser Diode, Fluorescence Spectroscopy, Photosynthesis
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