As a highly sophisticated strategy for environmental control in greenhouses, the concept of speaking plant approach (SPA) has attracted a great deal of attention. Sensor-based plant diagnosis techniques to monitor plant physiological status are the first and most important step in SPA. Currently, imaging systems for plant growth monitoring are especially required in wide range of agricultural production not only in advanced greenhouses but also in traditional vinyl houses. In this study, we developed a compact- and lightweight- multiple imaging system that is consist of an infrared camera filtered with a long-pass filter (λ > 620 nm), a color camera, and blue/red/infrared/white LEDs. The developed imaging system enable us to conduct chlorophyll fluorescence imaging, NDVI imaging, and color imaging at the same time. We applied the system for imaging of tomato plant grown under greenhouse condition and successfully obtained an obvious chlorophyll fluorescence induction curve derived from a series of chlorophyll fluorescence images and NDVI and color images that are useful to identify the matured tomato fruits.
