Differential benefits of arbuscular mycorrhizal and ectomycorrhizal infection of Salix repens

The functional significance of arbuscular mycorrhiza (AM) and ectomycorrhiz a (EcM) for Salix repens, a dual mycorrhizal plant, was investigated over t hree harvest periods (12, 20 and 30 weeks). Cuttings of S. repens were coll ected in December (low shoot P) and March (high shoot P). Glomus mosseae ta n arbuscular mycorrhizal fungus, AMF) resulted in low AM colonization (<5%) , but showed large short-term (<12 weeks) effects on shoot growth and root length. Hebeloma leucosarx (an ectomycorrhizal fungus, EcMF) resulted in hi gh EcM colonization (70%), but benefits occurred over a longer term (>12 we eks). Furthermore, G. mosseae colonization resulted in higher shoot P uptak e, shoot growth, root growth and response duration for S. repens collected in December than for those collected in March, whereas with H. leucosarx an d the non-mycorrhizal treatment there were no differences between cuttings collected on different dates. Low AMF colonization was effective in the sho rt term for cuttings at both collecting dates. Low AMF colonization of S. r epens occurred irrespective of the amount of AMF inoculum used. The intensi ties and relative amounts of AMF structures in S. repens and Trifolium repe ns were compared over three harvest peri ods (12, 20 and 30 weeks) to asses s plant species effects on AM colonization patterns.