Abstract
(1) In the present paper, the results of the writer's experiments on the effect of copper sulphate mixed in the culture solution or in the soil in WAGNER'S pots upon the susceptibility of the rice plant to the Helminthosporium disease were described.
(2) In the first series of experiments by solution-culture, the development of the rice plant was accelerated more or less in the 1/1, 000, 000 Mol. or 1/500, 000 Mol. addition of copper sulphate than on the control-solution.
(3) The susceptibility of the rice plant grown by solution-culture to the Helminthosporium disease showed a tendency to decrease inversely with the increase of the amount of copper sulphate added.
(4) In the second series of experiments using the soil in pots, the 1 ngth of rice-seedlings grown on soils containing a little amount of copper sulphate and the number of their leaves exceeded those as controls, although no difference was visible for the naked eye.
(5) In all the experiments of the second series, the diseased spots per unit area of leaves were always less in number in the seedlings grown on the soil containing copper sulphate than in those of controls.
(6) The growth of the causal fungus, Ophiobolus Miyabcanus, was more vigorous in the decoction of the seedlings grown as controls than in the decoction of those on soils with copper sulphate.
