The role of the extraradical mycelium network of arbuscular mycorrhizal fungi on the establishment and growth of Calamagrostis epigejos in industrialwaste substrates

The effect of inoculation with native and non-native arbuscular mycorrhizal fungi (AMF) on the establishment and growth of the grass Calamagrostis epi gejos was studied in three industrial substrates from (1) a sedimentation p ond with pyrite smelter waste at Chvaletice, (2) a power station fly ash de posit at Opatovice and (3) a Miocene clay spoil bank from a coal mine at Br ezno. The mycorrhizal growth response differed between developmental stages of the host plant and various substrates. Older nurse plants in central co mpartments of rhizoboxes (separated by a nylon mesh from two lateral compar tments) showed different growth response to inoculation with AMF in compari son with seedlings transplanted into lateral rhizobox compartments 3 months later, after the establishment of the network of extraradical mycelium (ER M). Nurse plants cultivated in industrial substrates and in the control sub strate sand showed neutral or negative response to AMF inoculation. The see dlings showed neutral or positive effects of inoculation when grown in indu strial substrates, while in the sand the response was negative for all AMF isolates. The disturbance of ERM links between the central and lateral comp artments delayed significantly mycorrhizal colonisation of seedlings; howev er, a negligible effect of ERM disturbance on the growth of seedlings was f ound. No differences in the development of native and non-native AMF isolat es in the industrial substrates were found except for Glomus mosseae BEG99 from Brezno spoil bank growing better in the native substrate as compared t o the non-native isolate G. mosseae BEG25. Mycorrhizal colonisation initiated from an established ERM network radiatin g from the nurse plant supported early developmental stages of C. epigejos in industrial substrates. However, the disturbance of ERM links between nur se plants and seedlings had no effect on the growth of seedlings, which did not support the hypothesis about the role of ERM links in intraspecific in teractions between differently aged grass plants. (C) 2001 Elsevier Science B.V. All rights reserved.