ON THE NATURE OF THE GROWTH PROMOTING SUBSTANCE EXCRETED BY THE “BAKANAE” FUNGUS

Abstract

1. Hoping that the experimental results may aid the solution of the problem as to what the stimulating substance in the filtrate of the cultured solution of the “Bakanae’-fungus really is, the experiments were conducted from six different phases.
2. The optimum concentration of the filtrate resulting the “Bakanae” symptom seems to be between 10 and 1%.
3. The function producing the symptom is not common to the species of Fusarium, at least to Fusarium Lini.
4. The growth promoting substance is thermostable, neither enzymic nor volatile.
5. The substance is adsorbed completely by animal black.
6. The substance is diffusible through the semipermeable membrane.
7. By the difference of the cultural solution of the fungus, the filtrate does not cause the “Bakanae” symptom, for example the filtrates obtained from the cultures in the RICHARDS' solution omitted KH₂PO₄ or MgSO₄ or both of them do not cause any overgrowth of the rice-seedlings but checked its normal growth.