Spore production of Pyricularia oryzae was relatively abundant on rice straw decoction plus V-8 juice agar (R+V-8), rice straw decoction agar (R), yeast starch agar (Y) and V-8 juice agar (V-8), but it was poor on oat meal agar (O) and potato decoction agar (P), in 7 days culture at 27°C in darkness.
The spore production of the fungus on these media in 7 days culture at 27°C was increased by a continuous exposure to 20 watt “white” fluorescent lamp (Matsushita) at 30cm distance from the lamp to mycelium. A large amount of spores was produced on R+V-8, R, and V-8 media. The increase in the rate of spore production, however, was markedly higher on P and O media, on which the spore production in darkness was poor, than those on the other media.
The spore productions in three isolates of P. oryzae, namely H67-1, Ken 60-19 and Ken 53-33, on R+V-8 medium in 7 days culture at 27°C, were markedly increased when exposed to a continuous irradiation with 20 watt “black light blue” fluorescent lamp at 30cm distance from the lamp to mycelium. However, stimulative or inhibitory effect on spore production of three isolates of P. oryzae was not observed on the same medium in 7 days culture at 27°C when exposed to a continuous irradiation with 20 watt “pure red” “pure yellow” “pure green” and “pure blue” fluorescent lamps.
The spore production of three isolates of P. oryzae on R+V-8 medium, were markedly increased when exposed to a continuous irradiation with 340mμ or 365mμ wave length light obtained, through glass filters. Stimulative or inhibitory effect of spore production on the same medium was not observed when exposed continuously to lights with 380mμ, 401mμ 422mμ, 432mμ and 450mμ wave length.