報告書番号

U00020

タイトル（和文）

オゾン殺菌装置による水耕栽培ホウレンソウ萎凋病の防除

タイトル（英文）

Control of Fusarium wilt of spinach by using of ozone sterilizing system in NFT

概要 （図表や脚注は「報告書全文」に掲載しております）

オゾンとオゾン水を併用したオゾン殺菌システムを試作し，流液式栽培でのホウレンソウ萎凋病（フザリウム菌）の防除方法を検討した。試作したオゾン殺菌システムの構成は，オゾン発生器とオゾン処理タンク，オゾン水製造タンクである。培養液中のフザリウム菌は，オゾン注入率1.56mg/Lで殺菌された。その場合，オゾンと反応し濃度の低下するアンモニウムイオンを1.1mg/L，マンガンを0.1mg/L，鉄を0.15mg/Lオゾン処理後添加する必要があった。一方，ホウレンソウの根では，溶存オゾン濃度0.25mg/Lのオゾン水の15分間処理で殺菌でき，ホウレンソウの生育にも影響はなかった。ホウレンソウ栽培でオゾンガス・オゾン水併用処理を検証した結果，オゾン処理区では発病率を約20％以下に抑制でき防除効果が確認された。

概要 （英文）

Fusarium wilt of spinach by Fusarium oxysporum is one of the most destructive root diseases in hydroponics using the nutrient film technique (NFT). Newly developed ozone sterilizing system and the method of the ozonation were examined for sterilizing micro-conidia of F. oxysporum. The result were showed as follows,The ozone sterilizing system was equipped with an ozone generator, a tank for the sterilization of nutrient solution and a tank for the production of ozonated-water.The micro-conidia of F. oxysporum were suspended at a density of 1.0 x 10^4 cfu/mL in 80 liter of nutrient solution in stainless steel tank of the ozone sterilizing system, and was ozonated at the ozone injection rate of 0.19, 0.56, 0.93 and 1.56 mg-ozone/L, respectively. The number of micro-conidia in the suspension was decreased when the ozone injection rate was increased to 1.56 mg-ozone/L. The ozone injection rate of 1.56 mg-ozone/L or more reduced the number of micro-conidia in the suspension to 1 cfu/mL or less. However, this rate of sterilization condition also induced the reduction in some nutritive concentration (ex. ammonium ion, iron and manganese) in the solution. This means that it is necessary to add the nutrients after the ozonation. No living micro-conidia could be detected from the 1hr-immersed roots in the inoculum when the roots were exposed with the ozonated-water at the concentration of 0.25 mg-ozone/L after the immersion. Furthermore, the ozone and ozonated-water exposure was valuable to reduce the infection rate of the Fusarium at the actual cultivation condition using a NFT system.

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