Utilisation of various nitrogen sources, in particular bound soil nitrogen, by mycorrhizal fungi
Mycorrhiza-forming species mainly of the genera Amanita, Boletus, Rhizopogon and Tricholoma and some litter-decomposing species were employed. For ecological characterisation of the experimental material, most of these species were tested for the ability to produce the extra-cellular enzymes cellulase, pectinase, proteinase and laccase. The mycorrhiza-formers were clearly inferior to the litter-decomposers in this respect, although some deviations were noted. Of the synthetic nitrogen sources investigated, ammonium and asparagine were most readily utilised by the fungi, followed by glycine, acetamide, nitrate and glucosamine in that order. Unusable sources were diethylamine, proline and pyridine. Nitrite had a toxic effect throughout. Litter decomposers tended to be non-nitrate users but could more easily utilise amide nitrogen than mycorrhiza-formers. The result from an experimental series having raw humus as the only nitrogen source indicated that the mycorrhiza-forming fungi, like most of the litter-decomposers, could utilise to a very limited extent or not at all the nitrogen bound in the humus. The inoculation of cultures of pine seedlings on gamma-sterilised, N15- labelled raw humus with pure culture suspensions of different mycorrhizaformers and litter-decomposers influenced to varying degrees both the supply of assimilable nitrogen and plant development.
mycorrhiza; fungi; soil nitrogen
Studia Forestalia Suecica
Permanent link to this page (URI)