Development Of Monitoring System Of Greenhouse Crops Based On Chlorophyll Fluorescence Images

Greenhouse agriculture has become an important part of modern agriculture. Compared with traditional agriculture, greenhouse agriculture has significant economic, social and ecological benefits. To improve the level of agricultural automation, it has great significance to develop real-time monitoring system for greenhouse plant. Chlorophyll fluorescence of plant can directly reflect the level of its photosynthesis, and it can provide a direct method to detect the growth status of crops. For greenhouse crops, on the basis of the literature review, the quantitative relationships between different fluorescence parameters and stresses suffered by crops are discussed, characteristics of chlorophyll fluorescence images of crops under different stresses are studied, and a monitoring system to distinguish their growth status is developed. The major contents studied are as follows:(1) Develop an integrated system to collect the fluorescence images for greenhouse crops combined with detecting hardware. For large scale greenhouse, the hardware consists of three-dimensional walk subsystem, illumination subsystem, CCD camera and other components. Based on the principle of plant chlorophyll fluorescence, design the appropriate software for device drivers, equipment cooperative control and fluorescence images acquisition. The long-term practical application shows that the fluorescence images acquisition system is reliable, images are clear, sampling data is accurate.(2) Propose the preprocessing methods for original fluorescence grayscale images. Threshold segmentation method is successfully applied to extract plant from original images because only plant can produce chlorophyll fluorescence, thereby calculate images of plant fluorescence parameters Y(?) and Fv/Fm. In addition, the quantitative relationships between leaf water potential, the nitrogen content and the above fluorescent parameters are analyzed. Quantitative analysis shows that it is fully justified to use Y(?) and Fv/Fm to diagnose stresses.(3) With experiment of cucumber drought stress, cucumber nitrogen deficiency stress, and early tomato disease stress, further analyze detailed characteristics of fluorescence parameter images for greenhouse crops under different stresses. The experimental results show that the fluorescent parameter images can reflect stresses suffered by crops, which can be applied to determine growth status for greenhouse crops.(4) Based on the above experimental results, a set of rules to decide crops growth status are established and a corresponding diagnostic system is developed, which has run in a greenhouse for a long time. The results show that diagnostic system is reliable, user-friendly and easy to operate; the system has high judgment accuracy when diagnosing the growth status of cucumbers and tomatoes.