Ozone Microbubbles as Disinfection in Nutrient Solution and Their Effects on Composition of Fertilizer and Growth of Cultivated Plants

Abstract

To propose ozone microbubbles (O3MB) as a new disinfection method for the nutrient solution used in hydroponic culture, we investigated the disinfectant effect of O3MB against Fusarium oxysporum f. sp. melonis and Pectobacterium carotovorum subsp. carotovorum, which are a pathogenic fungus and bacterium that infect plants via the roots, and the effect of O3MB on the composition of nutrient solution and plant growth. Since O3MB dissolves more efficiently in solution than O3 millibubbles (O3MM) over a short period, it is regarded to be highly effective as a disinfectant against F. oxysporum f. sp. melonis and P. carotovorum subsp. carotovorum. Disinfectant effect was observed when O3MB treatment was performed once or twice a week at approximately 0.2 ppm of dissolved O3 in a nutrient solution kept at 20C. Concentrations of Mn and Fe in the nutrient solution dropped because of O3MB treatment; however, no effect was observed on other fertilizer components. Furthermore, O3MB had no adverse effects on the growth of lettuce that was cultivated in this study. While it is necessary to devise a way to counteract the deficiency of Mn and Fe in nutrient solution depending on the cultivated plant, this study suggests that O3MB can be used as a new disinfectant technique for the nutrient solution used in hydroponic culture.