This paper deals with the results of histochemical observations on the penetration of Cochliobolus Miyabeanus to the suscept-cells, and the relation between the occurence of Helmintho sporiose of rice plant and iron, especially organic iron in the rice plant.
Suscept-cell(variety Kyoto-Asahi) invaded by the fungus, became reductive states after 24 to 50 hours. As to K, Fe, and P_2O_5, no significant change were observed even after 50 hours. Hidrogen-ion concentration in the suscept-cell was about 6.4.
Other test plants - Te tep, Chowcowtow, Karalath, Baurash Murai (foreign varieties), Kameji, Ginbodzu, Uhei, Ginmochi (Japanese varieties), - were grown in Wagner's pots and histocbemical observations on the diseased tissues penetrated by the pathogen using leaf sheath method, spectrographical analysis by line spectrum, quantitative analysis of iron using pulfurich's photometer, were carried out.
Through histochemical observations, resistant varieties, especially in foreign varieties, strong Fe^<¨> reaction in the suscept tissues after 48 hours around the penetrated hyphae was ascertained.
Although the result of spectrographical and quantitative analysis of iron did not show any difinite tendency between the rice varieties and total iron contents, the ratio of organic iron; total iron was clarified and it was suggested that these ratio might play a significant role in the resistance mechanism.