Application Of Infrared Thermal Imaging In The Detection Of Plants Disease At An Early Stage

Early detection of plant disease based on thermal infrared imaging technique can help us to prevent the spread of plant disease effectively and stop the disease in the beginning. It can not only improve the yield and quality of crops, but also reduce the dosage of pesticide. Therefore the application prospect of this research is very attractive. The main research contents and results were as follows:1,The research advancements and achievements in the field of detecting plash disease and plain physiological status using computer vision technique were reviewed. The existed problems and requirements were put forward.2,Three research systems were set up. The visible light image grabbing system was composed of a CCD camera (TMC-7DSP (PULMX) CCD), a frame grabber and so on. The infrared thermal imaging system was composed of a thermal imager (SAG90), Sony recorder, a frame grabber and so on.3,When the cucumber downy mildew infection, the virus will affect the cucumber leaves stomatal regulation,and then resulting in the surface temperature of cucumber leaves change; because of transpiration of cucumber leaf tissue was correlated to leaf temperature in a negative linear manner, so as the cucumber downy mildew in the leaves expand, the surface temperature of cucumber leaves would have a corresponding change; when using infrared imager to detect the cucumber downy mildew in a continuous,non-destructive way, found there have about 1.0℃temperature difference between the infected leaves and controlled leaves. The results showed that: under controlled conditions, the temperature discrepancy could significantly level the severity of the infected leaves; So, Temperature difference could served as an important regulation in leaf temperature response to cucumber downy mildew disease4,In this study we analyze the infection situation of plant and thermal image. Found the infected leaves showed a pre-symptomatic decrease in leaf temperature about0.5～1.2℃over than that of the healthy leaves.Under control conditions, so the temperature difference allowed the discrimination between the infected and healthy leaves before the appearance of visible necrosis on leaves by thermal imaging.