Research On Plant Photosynthetic Monitoring System Based On Fluorescence Induction

Photosynthesis is an important basis for plant life activities.Studying it can reveal the mechanism of photosynthesis,improve plant production efficiency,cope with global climate change and promote environmental protection.Obtaining photosynthetic information of plants is an important step in the study of photosynthesis.The half-leaf method takes a long time and cannot be measured continuously.The O₂ method and the isotope measurement method often require leaves to be treated in vitro and the accuracy is not high.Although the infrared CO₂ gas analysis method has higher accuracy However,the measurement will cause some damage to the blade.The chlorophyll fluorescence parameters of plants are one of the important indicators to measure the photosynthesis of plants.Using chlorophyll fluorescence technology can conduct photosynthesis research quickly,non-destructively and with high precision,which can well solve the above problems.In this study,the chlorophyll fluorescence induction method is the core,using saturation pulse technology and modulation technology,using amplifier circuit and analog-to-digital conversion circuit to amplify the weak fluorescent signal,and realize the high-precision monitoring of photosynthetic information.A portable plant photosynthetic monitoring system with friendly human-computer interface and remote transmission of data was designed.At the same time,the method of retrieving photosynthetic rate by chlorophyll fluorescence signal was studied.The instrument comparison test and the comparison test of different leaves were carried out with strawberry and tobacco as the test objects,and the measured data were analyzed to verify the accuracy of the monitoring system.Below are key research findings:（1）Developed a plant photosynthesis monitoring hardware system induced by chlorophyll fluorescence.In this thesis,the Arduino control board is used as the main control unit,and the Raspberry Pi is used as the interactive carrier.The excitation light source module,the fluorescence acquisition module and the power supply module are designed to realize the high-precision collection of chlorophyll fluorescence signals,thereby calculating plant photosynthesis efficiency and other information..In order to facilitate portability and protect the hardware,a physical structure based on 3D printing is designed.（2）A software system for monitoring plant photosynthesis induced by chlorophyll fluorescence was designed.According to the overall framework design,it is divided into three parts:measurement terminal,human-computer interaction terminal and server monitoring background.The measurement terminal is written in C++language,and communicates with the human-computer interaction terminal through the serial port.The human-computer interaction terminal uses the Python language and the Py Qt framework to realize the development of the interactive interface on the Raspberry Pi,which simplifies the operation steps and provides a data viewing page;the measurement data is synchronized to the monitoring background through the network to ensure real-time data sharing.The server background is based on Java,Vue,Mysql and other technologies to realize remote monitoring of data and provide web access capabilities.（3）A photosynthetic rate inversion model was constructed.Four crops of corn,wheat,tobacco and strawberry were selected as the research objects.Based on the chlorophyll fluorescence data collected by the self-developed monitoring terminal and the photosynthetic rate data collected by the photosynthetic instrument,support vector machine regression（SVR）and partial least squares regression（PLSR）,（KNNR）,adaptive enhanced regression（Ada Boost）,and gradient boosted tree regression（GBRT）,all have achieved reliable results,and GBRT has the best effect.In the inversion of photosynthetic rate,the coefficient of determination of corn reaches 0.74,that of wheat reaches 0.76,that of tobacco reaches 0.71,and that of strawberry reaches 0.77.（4）Carried out a system test comparison experiment.Through the instrument comparison test,the self-developed monitoring instrument and the commercially available instrument have a determination coefficient of 0.83 in the measurement of strawberry photosynthetic efficiency,and a determination coefficient of 0.82 in the measurement of tobacco photosynthetic efficiency.There is a significant correlation between the two;the comparison test results of different leaves It shows that the self-developed monitoring instrument is consistent with the actual situation.These experiments prove that the self-developed monitoring instrument has high accuracy.The overall function test of the monitoring system is normal,can meet the requirements of real-time monitoring,and has obvious advantages in data transmission,storage,expansion and price.The plant photosynthesis monitoring system based on fluorescence induction in this study has passed the relevant experiments and tests,and can monitor the photosynthesis of plants in real time without damage.The measurement results are stable and reliable,and the cost is low.Development provides strong support.