ABSTRACT
In present agriculture, hydroponic culture increases year by year because it off ers the prospect of high productivity in limited cultivation space. Nutrient solutions used in hydroponic culture are commonly disposed after use. However, from the point of view of environmental protection, reusing nutrient solutions may be needed in the near future. However, because cyclic use of nutrient solutions causes rapid spread of disease by infection via roots throughout an entire cultivation facility, sterilisation is indispensable.
