The Research On The Relationship Between Laser Strength And Excitated Chlorophyll Fluorescence Strength

Digital agriculture is the foundation of modern agriculture. The test of plant eco-physiological indexes changing as the fundamental factor of the digital agriculture is the effective technology for managing plant culture, preventing growth obstructions and analyzing environment effects. Furthermore, it is also significant to enhance agricultural production.Spectrum technology as a non-damage measure has many advantages including fast analysis, high efficiency, low cost, excellent repeatability and operating facility. Using laser to be excitation light source can boost fluorescence intensity more effectively, and then the sensitivity for analysis can be improved. Development of laser technology provides potential research method for bioinstrumentation in modern agriculture.This research focuses on laser inducing chlorophyll fluorescence detection and analysis by the analysis of factors which affect chlorophyll fluorescence, to explore the relationship between laser strength and corresponding induced chlorophyll fluorescence strength, and confirm the feasible laser strength, which provides fundamental experimental data and theory evidence for this research. The main contents include:1)The influences of different soil conditions on chlorophyll fluorescence strength;2)The influence of chlorophyll content on fluorescence strength;3)The research of chlorophyll fluorescence strength induced by laser with different wavelengths(473nm,660nm);4)The influence of chlorophyll fluorescence parameter on chlorophyll fluorescence strength;5)The comparison of fluorescence strength between inferior quality leaves and normal leaves in same laser strength;6)The study of the connection between laser strength and chlorophyll fluorescence strength;7)By synthesis analysis, the feasible laser strength is confirmed; In experiment, the laser used as excitation light source irradiates directly on plant leaves to excitated chlorophyll fluorescence. In order to test chlorophyll fluorescence parameter, photosynthetic rate, chlorophyll content, soil water content, weather and fluorescence spectrum are measured by plant efficiency analyzer(PEA), CI-310, spad502, soil-moisture content analyzer, weather station and spectrograph . Some important conclusions are drawn.1)Experiment with different soil stress as external conditions, focuses on the response of plant fluorescence strength when external conditions changed, by changing irrigation norm and fertilizing amount, and then fluorescence strength is analyzed. The result shows that fluorescence strength increases firstly and then lowers with the increasing of irrigation norm and fertilizing amount.2)Connections between chlorophyll content and fluorescence strength of living leaves are researched. One-way analysis of variance is done for leaves with same photosynthetic rate and different chlorophyll content. The result shows that the influence of different chlorophyll content on fluorescence strength is significant distinct. Depending on curve fitting of fluorescence spectrum excitated with different strength and chlorophyll content, the best strength is 5.0mW. Under this condition, the equations of red and blue light are:3)The influence of chlorophyll fluorescence parameter on chlorophyll fluorescence strength is analyzed by measuring chlorophyll fluorescence parameter. We study the connection of Fv/Fm and fluorescence strength through their two-stage curve fitting. The red and blue fitting equations are4)The spectrums of inferior quality leaves and normal leaves under same laser strength are collected, and then compare and analyze their fluorescence spectrum respectively. These conclusions provide the fundament for nutrient diagnosis of plants. We obtained the result that the inferior quality leaves fluorescence strength is higher than normal leaves by characteristics of spectrum analysis of the two leaves such as wave shape, peak value and peak width. There is various in wave shape, but at peak position red or blue shift is not obvious.5)The research on relationship between laser strength and fluorescence strength is one emphasis in order to provide the theory evidence for research and development of plant growing diagnosis sensor. The relationship between laser strength and fluorescence strength is linear. Depending on the comparison and analysis of the fluorescence spectrums excitated by red and blue wavelength, we established regression equations of laser strength and fluorescence strength of two wavelengths: (R2=0.9297) and ( ). During the modeling of the different wavelengths, we also obtained that the effect of blue light is better than red light for spectrum excitated.6)During the process that chlorophyll fluorescence is induced by different wavelengths laser and different fluorescence strength with two wavelengths in same laser strength are analyzed by signed rank. Theoretically there is significant distinct difference between the excitated effects of two wavelengths, and then we compared the spectrum characteristic dealt with two wavelengths.7)It is the other emphasis to confirm the appropriate laser strength in this research. In this part, laser strength stability, spectrum characteristic, fluorescence strength response degree to environment, the relationship between chlorophyll content fluorescence strength and economic, and practical factors are all analyzed. Finally, the red and blue wavelengths with 5.0mW laser strength are appropriate for spectral analysis. This result provides the experiment fundament and theory basis for research and development of sensor.