2008 Volume 7 Issue 2 Pages 309-315
In tomato hydroponics, the construction of an efficient recycling system for liquid waste has been expected. In this study, we developed a nutrient sterilization device using silver-supported photocatalyst, and evaluated its ability to sterilize specific fungi, suppress infections and influence on plant growth, fruit quality and yield of tomato. The sterilization device is especially characterized by the silver-coated non-woven cloth filter and visible light source. Using this device, Ralstonia solanacearum and Pythium aphanidermatum in nutrient solution were almost completely eliminated 8 and 4 minutes after innoculation, respectively, and Fusarium oxysporum was also decreased to 3% of the primary number of pathogens after 16 minutes. Investigation of the effective flow speed of nutrient solution from 10 L·min−1 to 20 L·min−1 for sterilizing Fusarium oxysporum showed that the sterilization ability of the device improved as the flow quickened. A closed hydroponic system equipped with this sterilization device could remarkably suppress the infection of root rot to plants. Consequently, significant difference was not detected for plant growth, fruit quality, yield of tomato and concentration of inorganic elements in the nutrient solution between the system and the control. Furthermore, neither conspicuous elution of silver ion into nutrient solution nor accumulation of that into tomato fruits in the system was recognized compared with the control. Our results demonstrated that the sterilization device utilizing the silver-supported photocatalyst is highly useful for practical tomato hydroponics.
