Based On Infrared Spectroscopy Study On Rapid Measurement Of Plant Volatiles

Plants produce volatile organic compounds(VOCs)related to their state after being subjected to biotic and abiotic stresses.The health status of plants can be quickly and nondestructively determined by detecting these VOCs.The existing detection technology has defects,such as gas chromatography-mass spectrometry,electronic nose,electrochemical sensor,and so on,because the plant volatile has complex components,low concentration,and difficult enrichment,and are unsuitable for detecting the plant volatile.Given the above situation,based on infrared spectroscopy,using Fourier transform infrared spectrometer and tunable diode laser absorption spectroscopy,this paper researched the rapid measurement method of plant volatile.The main research contents and conclusions are as follows:1.The feasibility of rapidly detecting tomato volatiles by Fourier transform infrared(FTIR)spectrometer was studied.Based on the previous research results of the team,the study took the tomato plant as the research object.It used the FTIR combined with the long optical path gas cell to detect the VOCs of the tomato plant when its state changed.The results showed that methanol and terpenes were detected in the spectrum produced by mechanically damaged tomato plants,and the output concentrations of these two substances changed with time.In the VOCs spectrum produced by tomato plants infected with gray mold,methanol,ammonia,and other substances were detected.These two substances were related to the degree of infection.The results are consistent with those of the proton transfer reaction mass spectrometer.In addition,principal component analysis was also used to analyze the spectral data and successfully classify the VOCs in healthy plants and other states.2.Based on FTIR detection results,a portable tunable diode laser absorption spectroscopy system was built to detect ammonia produced by plant disease.The system uses a distributed feedback laser and a self-made circular gas cell to detect the ammonia absorption peak at the frequency of 1512 nm.It combines wavelength modulation spectroscopy to improve the measurement sensitivity of the system.After setting up the system,the performance of the system was measured for a long time using standard ammonia with concentrations of 2 ppm and 50 ppm.The experimental results show that the portable tunable diode laser absorption spectroscopy system built in this paper can detect ammonia at the sub-ppm level,which can be used to detect the ammonia of diseased plants.To sum up,this paper researched the rapid measurement method of plant volatile,indicating that the detection technology based on infrared spectroscopy can be used to detect plant volatile in different scenarios and expands the application of infrared spectroscopy technology in botany and agronomy.