トマトロックウール栽培における銀担持光触媒を利用した殺菌装置の殺菌効果と収量,品質,培養液無機成分濃度に及ぼす影響(作物保護)  [in Japanese] Effect of Silver-supported Photocatalytic Sterilizer on Sterilization, Yield, Quality and Nutrient Element Concentrations in the Tomato Grown under Rockwool Culture(Disease & Pest Management)  [in Japanese]

トマト養液栽培における排液再利用のため,銀担持光触媒を用いた培養液殺菌システムを開発し,トマト主要病原菌に対する殺菌効果,病害伝染抑制効果,生育,品質,収量に及ぼす影響を検討した.殺菌装置は銀担持不織布の殺菌フィルターに蛍光灯の可視光を照射することによる光触媒殺菌装置とした20Lの培養液に病原菌懸濁液を希釈し,培養液タンクと殺菌装置の間で循環することにより,青枯病菌は8分後,根腐病菌は4分後にほぼ死滅し,根腐萎凋病菌は16分後に初発菌数の3%の菌数になった.また,根腐萎凋病菌で殺菌装置を通過する培養液の流速を10L・min^<-1>〜20L・min^<-1>で検討した結果,流速が速いほど殺菌効率が高かった.殺菌装置を組み込んだ培養液循環システムは余剰液を殺菌し培養液タンクに戻す方式とした.このシステムでのトマト根腐病の伝染は局所的な感染にとどまり,顕著な伝染抑制効果が見られた.また,生育,品質,収量,および培養液無機成分濃度に対する影響はほとんどなく,培養液中,果実中の銀イオン濃度の上昇もなかった.

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.