Specific Differences in Matter Production and Water Purification Efficiency in Plants Grown by the Floating Culture System

Abstract

Matter production and water-purification efficiency were compared among nine gramineous plants and one cyperaceous plant grown by the floating culture on natural water in order to determine the plant characters useful for selection. The results were as follows : 1) When a slow-release fertilizer was applied at the base of the roots, the dry matter was increased in all species. However, there were specific differences in the effect of fertilizer on the removal of nitrogen (N) and phosphorus (P) from water. This was due to the difference in the ability to take up N and P among plant species. Therefore, selection of the plants highly reactive to fertilizer is an important character for the enhancement of both plant production and water purification. 2) The uptake of N and P by rice plants was inhibited by a high water pH, but natural water with a pH increased by the rapid growth of algae could be purified by uptake by the umbrella plant.