2020 年 32 巻 1 号 p. 37-43
We investigated a plasma-based sterilization method for preventing Fusarium wilt disease in a spinach hydroponic system. Spinach seedlings were immersed in a Fusarium oxysporum suspension and then planted inside the hydroponic container. The plasma was irradiated to the roots in the nutrient solution; after cultivation, the incidence rate of wilt disease was inspected. It was observed that in case of plasma irradiation, the incidence rate reduced to less than 20 % within 5 min. This demonstrated the disease prevention efficacy by plasma irradiation. However, the incidence rate was found to be about 50 %, which was almost the same as that in the no-plasma condition, within 10 min of irradiation, and reached 90 % within 25 min of irradiation. Thus, plasma irradiation acts efficiently on the infected seedlings in solution with naturally rising temperature and exposure to ultraviolet light and some active radicals. These factors significantly contribute to the sterilization operation and may promote infection or disease prevention depending on the irradiation exposure time.