Interactive effects of substrates and ectomycorrhizal colonization on growth of a poplar clone

A balsam poplar clone (Populus trichocarpa cv. Weser 6) was inoculated by t wo ectomycorrhizal strains (Laccaria bicolor MW 158 and Paxillus involutus 1444) in Kick-Brauckmann-pots. The substrates were two arable sandy soils ( Cambisols) with different organic matter content and nutrient supply. One s oil (WIL) was rich in organic matter (C-org = 1.6%) and total nitrogen (N-t = 0.14%), whereas the other soil (RIE) had low contents of C-org (0.8%) an d N-t (0.08%). Leaf nutrient concentrations, shoot lengths, root and shoot biomass production and nitrogen accumulation in the :biomass were determine d to discover possible inoculation effects. Mycorrhization indices (% colon ized fine roots) of 36% with Laccaria bicolor and 40% with Paxillus involut us were observed on the C-org rich soil (WIL) in contrast to 16% and 14% on the C-org poor soil (RTE), respectively. Inoculation of poplar on the soil WIL increased shoot length, biomass production, shoot:root ratio and total N uptake of the cuttings, whereas on the soil RIE only the shoot:root rati o increased and the N nutrition was improved. We conclude that interactions between soil and fungus should be rested when choosing ectomycorrhizal str ains for inoculation.