The Design And Implementation Of Portable Detection System For Chlorophyll Fluorescence

Chlorophyll is the main pigment in plant photosynthesis,and its content and physiological activity directly determine the photosynthetic ability of plants.Light energy absorbed by chlorophyll is mainly used for photosynthesis,while a small amount of it for exciting fluorescence.Chlorophyll fluorescence will increase when photosynthesis is inhibited under stress conditions.Thus,detecting the distribution and variation of chlorophyll fluorescence in plants can reflect the photosynthetic ability,thereby reflect the physiological or stress state of plants.At present,the available chlorophyll fluorescence detection systems can be divided into portable single point detection system and chlorophyll fluorescence imaging system.Although fluorescence imaging system can directly obtain the spatial distribution of chlorophyll,and reflect the physiological state of plants more accurately and timely,it is usually only used in laboratory environment owing to its large size.In order to solve this problem,a small portable chlorophyll fluorescence image detection device is designed and implemented in this thesis.Firstly,a portable chlorophyll fluorescence imaging system was designed,which employs an LED as the excitation light source,a CMOS camera module as the imaging device.An integrated handheld structure was designed and used for clamping the leaf and acquiring fluorescence images.The field of view of the system is 40 mm×30 mm and the pixel size is 12 μm×12 μm.Secondly,a chlorophyll fluorescence image acquisition and analysis software was developed with a raspberry PI as the embedded running platform.The software use touch screen for setting imaging parameters,and the acquired fluorescence images from multiple measurements can be saved to a remote server via Wi-Fi.The whole system with the raspberry PI embedded system can be operated independently without a personal computer,ensuring the portability of the whole system.Finally,the portable system for chlorophyll fluorescence imaging is verified with imaging experiments on plant leaves of various states.In summary,the system is small and portable,which can acquire and save the fluorescence imaging on-site and can be used for field detection.This system has in the potential application for monitoring plant growth status and evaluating the impact of various environment factors on plant physiology.