Pathogen infection has greatly reduced crop production. As the symptoms of diseases usually appear when the plants are infected severely, rapid identification approaches are required to monitor plant diseases at early the infection stage and optimize control strategies. Hyperspectral imaging, as a fast and nondestructive sensing technology, has achieved remarkable results in plant disease identification. Various models have been developed for disease identification in different plants such as arable crops, vegetables, fruit trees, etc. In these models, important algorithms, such as the vegetation index and machine learning classification and methods have played significant roles in the detection and early warning of disease. In this paper, the principle of hyperspectral imaging technology and common spectral characteristics of plant disease symptoms are discussed. We reviewed the impact mechanism of pathogen infection on the photo response and spectrum features of the plants, the data processing tools and algorithms of the hyperspectral information of pathogen-infected plants, and the application prospect of hyperspectral imaging technology for the identification of plant diseases.

Using the discrete element method (DEM) to investigate the behavior of particles is a crucial strategy in the research and development of novel equipment. Green pepper (Zanthoxylum armatum) is a globally renewable plant-derived medicinal and food homologous commodity with a wide range of uses and great demand, but the mechanical properties needed to develop its processing equipment are scare. Thus, this case of study aimed to systematically explore the necessary input parameters to model green pepper, and to provide new insights for the guidance of future industrial applications worldwide. On the basis of the experimental measured physical properties, the contact properties of green pepper on zinc-coated steel were fist calibrated, and then used to determine the contact properties between particles. The differences between the experimental and simulation results were analyzed for selection and verification of the contact properties accurately. Difference analysis confirmed that the coefficient of restitution, coefficient of static friction and coefficient of rolling friction for contact between the particle and zinc-coated steel have values of 0.392, 0.650, and 0.168, and those coefficients for particle-to-particle contact have values of 0.199, 0.710, and 0.184, respectively. Discoveries in this work may contribute to the research and development of production equipment for green pepper.