Abstract
The present investigation was undertaken to ascertain the difference of fungicidal activity of methyl bromide to the fungal spores settled on the hulled rice and to the mycelia grown on or in the hulled rice. The hulled rice to be inoculated was sterilized at 12lbs. for 20 minutes by autoclaving.
Several grades of hyphal growth in the rice grains were obtained by changing the time of incubation. Microscopical observations were made on hand sections or frozen sections of the rice grains.
With regard to the resistance of spores and mycelia to methyl bromide, the latter has less resistance than the former. The mycelia were completely sterilized by fumigation at 45mg/l, 25°C for 18 hours, but the spores required 50mg/l for their complete sterilization.
The methyl bromide resistance of the hyphae within the grain varied according to the extent of mycelial invasion, the resistance of mycelia invaded in the aleuron layer being apparently less than that in the starch layer. The hyphae in the central part of the grain could be sterilized by about the same dosage as in the case of the spores on the grain surface.
