| Modern agriculture is developing toward precision agriculture and physical agriculture with the step of information technology.It is the keypoint that understanding the connections between plant photoelectric information and plant state,thus achieve non-destructive diagnosis of plant state.The aim of physical agriculture is to develop intervention technology with light,electricity and magnetism etc.based on electromagnetic information of plants,which can remarkably promote the germination and growth of crops and enhance the stress resistance of crops.Therefore,collection,analysis and interpretation of plant optoelectronic information are significant to the development of precision agriculture and physical agriculture.In this dissertation,the key problems of plant optoelectronic information analysis and application in precision agriculture and physical agriculture are studied,and a research idea was proposed that significantly promoting germination,growth and stress resistance of crops through coupling resonance between plant cell potential and external electric field according to plant potential fluctuation,and evaluating electric field biological effect rapidly,non-destructively and accurately according to plant’s own photon emission information.Based on the characteristics of plant potential fluctuation,the potential fluctuation signal of plant leaves were obtained by using plant potential fluctuation acquisition system.The collected potential fluctuation signals were decompose by complementary ensemble empirical mode decomposition(CEEMD)method and denoised by permutation entropy(PE)and soft threshold.Then the marginal spectrum was achieved by applying Hilbert-Huang transform(HHT)to denoised signal.plant leaf potential fluctuation characteristic parameters system based on marginal spectrum was established,in which spectral center frequency(SCF),spectral edge frequency(SEF)and amplitude index(AI)describe frequency domain distribution of plant potential fluctuation,marginal spectrum entropy(MSE)describes the complexity of the potential fluctuation,and action potential sensitive index Q represents sensitivity of potential fluctuation responding environmental changes.Study confirmed that the plant cell potential fluctuation is non-stationary,and the amplitude is very weak,but its marginal spectrum is stable continuous spectrum with very low frequency characteristics.The study also found that the marginal spectral distribution of maize seedling leaves potential fluctuations is very sensitive to drought stress,plant potential fluctuation parameter index system based on HHT method can sensitively reflect the physiological state of maize and its response under drought stress.Studies on different varieties of maize under drought stress show that maize with different drought resistance has different spectral variation of leaf potential fluctuations,and changes in marginal spectrum SEF,SCF and MSE sensitively reflect the process of leaf cells injured by drought stress and adaptation.In order to study photon emission characteristics of seeds and leaves,an ultra weak photon emission detection system based on photomultiplier,integrated excitation light and shutter control was designed and built.This system can precisely control excitation light wavelengths,excitation light intensity,excitation time and detection time.Thus,a reliable measurement of biological ultra weak photon emission and its spectral signatures be realized.On the information extraction of photon emission,nonlinear dynamic model parameters analysis method and evaluation system was proposed.Studies on ultra weak photon emission from germinating maize seeds show that spontaneous photon emission intensity ISL and induced photon emission kinetic parameters which include initial photon number I0,coherence time τ and integrated intensity I(T)are closely related to cell life activities respectively.according to measuring and analyzing these parameters,understanding and judgment dynamic changes in cell metabolic system real time,sensitively and non-destructively during sees germinating can be achieved.Based on the study results of plant potential fluctuation information and photon emission information,an extremely low frequency and high voltage pulsed electric field(PEF)treatment system based on the marginal spectral characteristics of plant potential fluctuation was developed.The germination process of maize seeds was interfered by high voltage PEF with different frequency of 0.2Hz～15Hz.The effect of PEF was evaluated by ultra weak photon emission and physiological index during seed germination,and the optimum frequency of PEF was determined.The comparison of high voltage PEF and high voltage electrostatic field(HVEF)treatment on germinated mung bean showed that the effect of extremely low frequency PEF treatment on seed germination was more significant than HVEF treatment.The reasons for the differences were discussed from the aspects of protein synthesis,superoxide free radical content,SOD and POD activities.The research on ultra-weak photon emission information also showed that the extremely low frequency PEF treatment could effectively improve the drought resistance of maize at germination and seedling period.Furthermore,spontaneous photon emission and induced photon emission can be used to sensitively diagnose orderness of seed cell tissue,interaction between function molecules and metabolic regulation situation of seeds under drought stress during germination and seedling period,thus evaluating seeds drought resistance.Interpretation of plant photoelectric information and research on PEF biological effect based on the photoelectric information not only reveal the characteristics and biological significance of plant’s own photoelectric information,provide a reference for new technologies of precision agriculture based on plant’s own photoelectric information,but also lay the foundation for further research work on biological effects of electric field and developing new technology of physical agriculture based on electric field interventions. |
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