| The agricultural industry relies heavily on the use of pesticides for sustainable management of crop pests and diseases.In order to prevent environmental pollution and loss of pesticides,it is necessary not only to use pesticides efficiently and fully,but also to determine the distribution of pesticides in crop leaves with reliable and intuitive methods.At present,there are many methods to detect fog droplet deposition,such as laser scanning,high-speed photography and other optical techniques.Fog drop sampler was used instead of plant leaf measurement.Measurement of fluorescent tracer solution on elution leaves.These detection methods or instruments are expensive,bulky,not suitable for field measurement,or have high requirements for experimental operation,which cannot reflect the deposition and distribution of fog droplets on crop leaves,and the collection process is complicated.In order to detect the deposition parameters of fog droplets on field crops and reflect the distribution of fog droplets on crop leaves,this paper proposed a method for direct detection of fog droplets deposition on leaf surfaces.The following four aspects were studied for this method:1)Design of direct detection method for deposition distribution of fluorescent fog droplets on leaves: image processing technology is used to identify and extract fluorescent fog droplets on leaves of crops and analyze the deposition parameters of fog droplets.A fluorescence fog droplet detection device was designed according to the method of direct detection of the deposition and distribution of fluorescence fog droplets on leaves.Smart phones were selected as the camera to collect images and Image J was used as the image processing software to study the excitation light source conditions suitable for the detection device.2)Selection of fluorescent staining agents: six fluorescent staining agents were screened and fog drop coverage was compared.It was found that the fog drop coverage of solvent green 7 and Acid Brilliant Flavine 7G was significantly higher than that of the other four fluorescent staining agents.The results showed that solvent green 7 and Acid Brilliant Flavine 7G had less decomposition after exposure to light,and had good photostability,which could meet the needs of long time exposure in field detection.Solvent green 7 meets the conditions of distinguishing fluorescent fog droplets and leaf background during image processing,and the concentration range is 0.6～1.2g/L.Acid Brilliant Flavine 7G should be used at a concentration above 3g/L.The economic indexes of solvent green 7 and Acid Brilliant Flavine 7G were compared.3)Study on spreading and fluorescence intensity attenuation of solvent green 7solution on different leaves: Experiment measured the 1 g/L solvent green 7 solution in peppers,tomatoes,rape,four cucumber leaf surface contact Angle and the spreading area,examines the droplets after adding solvent green 7 changes in leaf spreading area,on the basis of droplets on the four blade fluorescence intensity attenuation of different time,analyzed the solvent green 7 as the applicability of the fluorescence tracer.It was found that when green 7 was added to cucumber leaves,the droplet coverage and diameter were larger than those measured with deionized water.The droplet coverage and droplet diameter of pepper,tomato and rape leaves had little change.In the first four minutes,the average fluorescence intensity of the fog drops on the leaves of pepper and rape almost did not decay,and then the decay was slow.The average fluorescence intensity of the fog drops on the leaves of tomato and cucumber was always decaying,and the decay rate of the average fluorescence intensity was fast.4)Deposition effect test of direct detection method of fluorescence fog drop deposition distribution on leaves: The area of single fog drop obtained by direct detection of fluorescence fog drop deposition distribution on leaves was compared with the area of single fog drop measured by three-dimensional superdepth of field microscope to evaluate the accuracy of fluorescence fog drop detection by this method.The relative error of the two results is 2.41±1.97%,and the error is less than 5%.The droplet area measured by the direct detection method was close to that measured by the instrument.The relative error of the two methods was only 1.67% when compared with the detection results of water sensitive test paper. |
