Analysis Of Effect Of Drought/NaCl Stress On Soybean Based On Chlorophyll Fluorescence Kinetics

In recent years,chlorophyll fluorescence kinetics have been favored by various scientific research institutions in the field of plant detection for its advantages of rapid and non-destructive detection of plant photosynthetic information.Based on the chlorophyll fluorescence kinetics,this study compares and analysis the effects of drought and NaCl stress on soybean photosynthesis.This study enables the automatic detection of soybean fluorescence information and the automatic recognition of soybean stress conditions.(1)This study analyzes the effects of soil drought stress on photosynthesis of soybean in seedling stage.In the experiment,three varieties of soybean are selected to be treated with three gradients of drought stress during seedling stage.Comprehensive analysis is conducted on the mechanism of response to drought stress and drought resistance of soybean by information of photosynthetic gas exchange,relative chlorophyll content,and chlorophyll fluorescence.Among them,soybean seedling soil stress will significantly reduce soybean photosynthesis [Fv/Fm,qP,qN,Y(II)] and affecting yield finally.However,under severe stress,the functions of various organs of the photosynthetic system are impaired,and the overall ability of photosynthetic function decreased.The Y(II)images and parameters can be used as the basis for judging the stress resistance of varieties,and the identification of Y(NO)images.It can be judged whether the plant suffers irreversible damage.(2)This study analyzes the effect of NaCl stress on photosynthesis of soybean at seedling stage.In the experiment of NaCl stress on soybeans,a greenhouse soil test is designed.Two cultivars of soybean are treated with four gradients of NaCl stress.Changes in photosynthetic gas exchange parameters,chlorophyll content,enzyme activity,chlorophyll fluorescence parameters,and images are analyzed under stress conditions.Discuss and summarize the effects of NaCl stress on photosynthesis of soybean and the differences in salt resistance mechanism between salt-tolerant cultivars and non-salt-tolerant cultivars.Among them,changes in the distribution strategies of dry matter and energy of salt-sensitive cultivar(Qihuang 35)are more pronounced than those of salt-tolerant cultivar(Xoudou 14)and more energy is distributed to the roots under stress,and salt-tolerant cultivars are more distributed in stress because energy is applied to leaves and increased POD activity to relieve the effect of NaCl stress.Under low concentration of NaCl stress,the main reason affecting the photosynthetic system of the two cultivars is stomatal limitation,but the main reason affecting the photosynthetic system of salt-sensitive cultivars under high concentration stress is of stomatal limitation and Y(NO)increases significantly simultaneously at the same time;NaCl stress decreases Fv/Fm,qP,Y(II)and other parameters to a certain extent,and Y(II)responded to the comprehensive status of plant photosynthetic system to some extent.In addition,comparing the NaCl experienment with the drought stress test.It can be seen that the qP and qN are inconsistent with the stress gradient,and qP and qN can be detected to identify the main stress is drought/NaCl stress.(3)Classify the fluorescence images obtained in the experiment,use a variety of methods to denoise the image,segment and other preprocessing and select the optimal processing method;after the image feature values are extracted and analyzed according to the image characteristics,PCA dimensionality reduction is performed on the feature values;using a variety of methods to model the image features and comprehensive analysis to select the optimal model,obtain based on image acquisition of fluorescence parameters and methods to identify the state of stress.Among them,in this study,two methods are used to predict the correlation coefficients of chlorophyll fluorescence parameters,and the model based on PLS fits this study better,as(qP and qN),;BP neural network and MLR are used to classify the stress state of soybean seedlings at the seedling stage,and recognition rate of BP neural network is more accurate,which is 0.9714.(4)This study designs an automatic detection and identification system for soybean chlorophyll fluorescence information,which can be used with a high-throughput phenotypic detection system,includes the design of an automatic electronic door system,the design of an RFID system,the design of an ultrasonic pitch system and the design of a control system.The main work flow of the system is to close the electronic door,identify the RFID of sample information,and adjust the distance of the chlorophyll fluorescence vision sensor after the sample to be tested is sent to the measurement position.After,the measurement is started and the sample is sent to the designated position after the measurement is completed and the systems are reset.This study analyzes the chlorophyll fluorescence information of soybean seedlings under drought/NaCl stress,constructs the chlorophyll fluorescence kinetics machine identification model,and design the automatic detection system.The study not only proposes to detect that the soil stress in soybean seedlings is drought/NaCl stress with detecting the images of qP,qN,and Y(II),but also proposes a innovational way based on machine vison recognition to rapidly detect soybeans subjected to irreversible light damage.That is,chlorophyll fluorescence is provided for seed selection and breeding with theoretical support and provides technical assurance for the machine to identify the state of stress.