Effects of isolates of ectomycorrhizal fungi and endophytic Mycelium radicis atrovirens that were dominant in soil from disturbed sites on growth of Betula platyphylla var. japonica seedlings

Effects of ectomycorrhizal fungi and endophytic Mycelium radicis atrovirens Melin (MRA) on growth of Betula platyphylla var. japonica seedlings were investigated under aseptic culture conditions. Three isolates of ectomycorrhizal fungi and two isolates of MRA were used. One MRA isolate was Phialocephala fortinii . Previous field work revealed that these isolates were dominant on the roots of B. platyphylla var. japonica seedlings grown in a mineral subsoil that had been exposed by the removal of surface soil. After a 100‐day incubation, the growth of the seedlings was significantly enhanced by the colonization of these ectomycorrhizal fungal isolates as compared with uninoculated seedlings. In contrast, the growth of seedlings was retarded by the colonization of the MRA isolates. The growth of seedlings that were co‐inoculated with ectomycorrhizal fungi and MRA was similar to that of uninoculated seedlings in most cases. These results suggest that ectomycorrhizal fungi have a beneficial effect on the growth of B. platyphylla var. japonica seedlings and that they suppress the deleterious effect of MRA. Thus, these ectomycorrhizal fungi probably have an important role in establishing B. platyphylla var. japonica seedlings during the initial stage of re‐vegetation following site disturbance by the removal of surface soil.