Effect of nitrogen level on acid phosphatase activity of eight isolates of ectomycorrhizal fungus Paxillus involutus cultured in vitro

The higher levels of nitrogen in ammonium form stimulated the growth of mycelia and increased the accessible as well as the total acid phosphatase activity of Paxillus involutus (Batsch) Fr. isolates grown in pure culture. Rates of mycelia growth and acid phosphatase activities varied widely from one isolate to another. Scots pine (Pinus sylvestris L.) seedlings were inoculated with different P. involutus isolates in axenic conditions. Shoots of pine seedlings with mycorrhizae contained more phosphorus than shoots of non-mycorrhizal seedlings. The relations between growth and phosphatase activity of P. involutus isolates and their efficiency in supplying the host plant with phosphate are discussed.