Fruit-body production and mycelial growth ofTephrocybe tesquorum in urea-treated forest soil

Tephrocybe tesquorum is an ammonia fungus that forms reproductive structures successively on the forest floor after treatment of the soil with nitrogenous materials such as aqua ammonia and urea. Forest soil was treated with urea at the rates of 0, 5, 10 and 20 mg/g fresh soil for 5 d in the laboratory, then sterilized by gamma-irradiation. Vegetative hyphae ofT. tesquorum were inoculated into the sterilized soil, and the number and weight of fruit-bodies formed and the length of vegetative hyphae, were measured for 20 d after the inoculation. Only in the urea-treated soil did this fungus produce vegetative hyphae and fruit-bodies. Fruiting started 4 to 6 d after inoculation. The weight of fruit-bodies and the length of vegetative hyphae increased with the increase in the amount of urea added. These results indicate thatT. tesquorum develops vegetative hyphae and fruit-bodies when ammonium concentration, is high in soil.