Effects of phosphorus on the excretion of oxalate, hydrion and phosphatase by ectomycorrhizal fungi Lactarius deliciosus and Laccaria bicolor
磷对外生菌根真菌松乳菇和双色蜡蘑草酸、氢离子和磷酸酶分泌的影响

Ectomycorrhizal fungi Lactarius deliciosus strains Ld-01, Ld-02 and Ld-03 and Laccaria bicolor S238N were cultured in liquid mediums with or without phosphorus. The growth and the excretion of oxalate, hydrion and acid phosphatase were then investigated. The results showed the growth of ectomycorrhizal fungi was most vigorous under moderate concentration of H2PO41- (1.147g NaH2PO4/L) and inhabitation of growth occurred under the conditions of deficiency or excess of phosphorus. The excretion rate of oxalate, hydrion and acid phosphatase by the fungi depended on concentration of phosphorus and changed in sequence of no phosphorus (0g NaH2PO4/L) > low phosphorus (0.229g NaH2PO4/L) > moderate phosphorus (1.147g NaH2PO4/L) > high phosphorus (5.735g NaH2PO4/L). In the same phosphorus treatments the excretion rate varied with species and strains. It seems reasonable to suggest that the external supply of phosphorus might have an effect on regulation of ectomycorrhizal fungi in activating inorganic and organic phosphorus in soil. Under the condition of lacking phosphorus or low phosphorus mycorrhizal fungi have stronger activation in utilizing phosphorus in soil, while under the condition of rich phosphorus, such an activation decreases. Phosphorus in soil could be effectively utilized by ectomycorrhizal fungi in this way.