2012 Volume 80 Issue 3 Pages 245-252
We investigated cadmium concentrations of rice plants and the growth and the yields by using four models of stratified paddy fields for three years. Two of them had water flow in an open system at the plowsole and the subsoil which became oxidation layers. The other two models had water flow in a closed system at the plowsole and subsoil which became reduction layers. The polluted soil thicknesses of those sets were 22.5cm and 32.5cm respectively and the cadmium concentration in those soils was 3.39mg/kg.
As a result, the range of cadmium concentrations in brown rice, and in the stems and leaves of those four were 0.000-0.200mg/kg, 0.059-1.250mg/kg, respectively. Also cadmium concentration in roots in the plow layers and that in the plowsoles and subsoils were 1.80-25.05mg/kg, 5.17-61.63mg/kg, 0.28-22.97mg/kg, respectively. In the two models with the same thickness of soil, significant differences in the number of leaf, dry weight of straw, the number of panicle, weight of brown rice, cadmium concentration in the roots in the plow layer and the plowsole and brown rice were observed. In those models with different polluted thicknesses and the same percolation patterns, significant differences in dry weight of straw, weight of brown rice and cadmium concentrations in the roots in the plow layer and the plowsole were recognized. From those results, it was clear that the difference of the polluted soil thickness influenced the concentration of cadmium in the rice plant, the growth and the yields under inundation during the cultivation with stratified models.