Abstract
We investigated the growth and the yields and the cadmium concentrations of rice plants by using two models of stratified paddy fields during three years. The first model had water flow in an open system under the plow layer and the plowsole and the subsoil became oxidation layers. The other model had water flow in a closed system under the plow layer and the plowsole and the subsoil became reduction layers. The plow layer and the plowsole in those models were made of polluted soil (3.39mg/kg) that existed in polluted paddy field.
As a result, the range of cadmium concentration in both models in brown rice, stems and leaves was 0.001-0.200mg/kg, 0.06-1.25mg/kg, respectively. Also the one in roots in the plow layers and that in the ones in the plowsoles were 6.62-25.05mg/kg, 9.85-61.63mg/kg, respectively. Cadmium concentration in every item with water flow in an open system became higher than that with water flow in a closed system. We realized that percolation patterns did not influence the growth of rice plants But the number of panicles, the total weight of straw and the weight of the brown rice with water flow in the closed system became higher than those with the water flow in the open system.
From these results, it became clear that the percolation patterns influenced the concentration of cadmium in the rice plants and the yields under inundation during the cultivation.
