Abstract
Conidiophores of the brown spot fungus of rice plant are produced on the “disintegrated zone” ofa diseased spot usually through stomata, when the affected leaves are still vigorous. Zone of the conidial formation enlarges gradually with the weakening of the leaves, and when the leaves die, it becomes to extend widely beyond the border of a diseased spot.
The formation of conidia has been observed by use of a modified TOYOTA and SUZUKI'S cell. The conidiophores appear first after about 5-14 hours and grow very slowly in the atmosphere of 18-26°C. in temperature and nearly saturated moisture. The cells of the conidiophores are at first homogeneous and hyaline, then they turn granular and dark from base. A conidium starts as a sharp protrusion at the apex of a conidiophore (fig. 3) and develops first into a tiny hyaline sphere. It turns to egg-shape, then to cylindric, and finally tapers slightly at its apex, in the course of growing to a characteristic shape and size. In succession with this, there appears septation and coloration of the conidia, and granulation of the cell contents (figs. 5-13). At the ripening of the conidium, the conidiophore begins to branch laterally at the directly beneath the conidial attachment (figs. 14-15). The branch grows vigorously and the conidium inclines sharply becoming as if it was lateral (figs. 16-17). After that, the second condium is produced in the same manner; and so on to the following ones.
