Spawn is pure culture of vegetative mycelium and has an important to play as the inoculum or seed in cultivating mushrooms. Different grains are used as spawn in button mushroom Agaricus bisporus. Various cereal grains, such as wheat, millet, barley, sorghum, brown rice, rye, oat were assessed to compare their suitability for production of button mushroom spawn. The mycelial growth rates, density, and the number of completed grains were measured from the twentieth day of inoculation. Wheat grains showed fastest mycelial growth with 8.4 cm followed by rye, oat, barley with 8.2, 7.5 and 7.3 cm, respectively. However, they were not significantly different at the 0.05 level. In the mycelial density, foxtail millet, barley, and sorghum were best compared with that of wheat grains. Especially, the number of grains which were completely colonized by mycelia were greatest in foxtail millet with 5,123 grains followed by proso millet, and wheat with 3,052 and 914, respectively. Based on the results obtained, barley, foxtail millet, and sorghum grains would be most appropriate for grain spawn production substituting wheat grain in button mushroom.

The effect of CO2 concentration (500, 3,000, 6,000㎕/ℓ) on the mycelial growth and fruit body primordium formation of Ganoderma lucidum on nutrient agar medium was examined. Optimum CO2 concentration for vegetative growth was above 3,000㎕/ℓ. Fruit body initiation was accelerated at higher than 3,000㎕/ℓCO2 exposure but the maximum number and size of primordia, and primordium color were not influenced by CO2 concentrations. Whereas each atypical fruiting structure forming stock culture showed different fruiting time under each concentration of CO2 exposure.