抄録
The author studied the causal nature of the toxic action of copper-ions on the growth of rice plant. The growth of the rice plant compared, in water culture, under the following conditions : - (a) The root is placed in the nutrient solution without copper. (b) The root is placed in the nutrient solution with copper. (c) One half of the root is placed in the solution without copper while the other half with. And the following conclusions are obtained. (1) The rice plant absorbs easily copper-ions in the nutrient solution. (2) The greater part of copper-ions absorbed is fixed in the root. The function of the root, especially its absorptive function, is thereby injured. (3)This injurious effect inhibits the root from absorbing the further amounts of copper-ions which seem to protect itself from the further action of copper. (4) The absorption of nutrients is also inhibited. Then the plant growth does not proceed normally. (5) Though onehalf root is placed in the nutrient solution with copper the plant does not suffer an injurious effect even in the concentration of 100 ppm of copper-ions if the other half is placed in the solution without copper. When the entire root is placed in the nutrient solution containing copper the plant dies in a short time even in the concentration of 50 ppm of copper-ions. (6) The rice plant growth well until the copper content of the top reaches the concentration of 100 gamma per 1 g of air-dried sudstance, regardless of the supply of nutrient solution.
