Abstract
The present paper deals with the result of the experiments on the relation between the susceptibility of naked barley to the small rust (Puccinia simplex (Korn. ) ERIKS. et HENN.) and the powdery mildery mildew (Erysiphe graminis-hordei DC. ) and the silicification of leaves. Water culture in which the silicic acid powders are applied diminishes remarkably the infection of the uredosoruses by the small rust and of the disease spots by the powdery mildew. It seems to be resulted by the fact that the silicic acid mainly prohibits the invasion of pathogene mechanically. The same fact is recognized in the narcosis-inoculation test of leaves in naked barley, namely the immediate inoculation after narcotization gave scarcely any result in the lot in which the silicic acid was applied. When the sun light was shortoned, the infection of the powdery mildew was found to be decreased parallel to the shortage of sun light, notwithstanding that the treatment favoured the histological condition to the fungus infection making the silicification of leaves imperfect and cuticular layers thin. This interesting facts seems to have reason in the relation between the plant nutrient and the fungus growth.
