| Water content is crucial for plant growth.If precise identification and rapid intervention of water content changes can be achieved in the early stages of water scarcity,it will greatly reduce the losses caused by water scarcity in plants and crops.However,during this stage,due to the small change in water content,there was no significant subjective visual change in plant leaves,and it is currently not possible to detect water changes during this stage.Therefore,there is an urgent need for a non-destructive testing technology that can achieve early changes in plant water content.This article utilizes the characteristic that the microstructure of leaf surface is affected by changes in leaf moisture content,and designs and builds a polarization imaging detection system.The system is validated and analyzed through experiments,preliminarily achieving early rapid non-destructive detection of plant leaf moisture content.This article first designs a time-sharing polarization imaging detection system based on the dual wave plate rotation method based on the characteristics and detection needs of plant leaves.It has the advantages of simple optical structure and low equipment cost.In the actual detection process,the main factors affecting system errors include light source stability,wave plate rotation angle deviation,and the angle between the camera and LED.Through simulation analysis of the impact of angle deviation on the Mueller matrix,it was found that the rotation accuracy of the wave plate needs to be controlled within 0.01°.Therefore,this paper designs a wave plate rotation table,which uses a stepper motor to control the rotation of the wave plate.The software is written using LabVIEW software to achieve automatic acquisition and storage of the stepper motor and images.In addition,the imaging effect was analyzed when the camera and LED were at different angles,and the results showed that the imaging effect was most ideal when the angle between the camera and LED light source was 20°.In order to achieve the detection of water content in plant leaves,this article first conducted continuous detection of detached holly leaves under natural water loss conditions.The results showed that the depolarization index image can distinguish holly leaves with different water contents.In order to verify the above rules,this article conducts polarization imaging detection on the pre processed holly leaves using the drying method,and the depolarization index image obtained can clearly display the changes in water content of holly leaves at various stages.The mapping relationship between the regression index value and the water content value obtained by fitting is:PΔ=0.074M_R~2-0.153M_R+0.357,and the value of the determination coefficient of the fitting curve is 0.95.By selecting different parts of holly leaves to validate the prediction model,the maximum relative error between the predicted water content and the actual value was 4.90%.This indicates that using this model can accurately obtain the water content of holly leaves.Polarization imaging detection technology has advantages over commonly used imaging detection technologies such as high contrast,strong ability to suppress background noise,and the ability to obtain more information about the target object.Therefore,this article utilizes the constructed polarization imaging detection system to perform polarization imaging detection on holly leaves,ultimately achieving early recognition and detection of changes in water content in holly leaves.This article aims to provide a new method for early identification of changes in plant water content,and also provides a theoretical basis for rapid non-destructive testing of other physiological states such as salt stress,acid stress,and fertilizer stress. |
