Final report on the project
G.R. Stewart and M.H. Turnbull, Department of Botany, University of Queensland
We have been able to demonstrate that colonisation of Eucalyptus and Acacia roots by various species of mycorrhizal fungi greatly enhances their ability to utilise organic sources of nitrogen. Particularly important is the finding that with some species of ectomycorrhizal fungi, protein can be hydrolysed and that the resulting amino acids can be used to support growth of the Eucalyptus or Acacia seedlings. We have isolated a range of ectomycorrhizal fungi from contrasting environments, from rainforest to dry sclerophyll forest. We have examined the potential of these fungi to utilise a range of organic and inorganic nitrogen sources. The objective is to determine if there is any relationship between the forms of nitrogen available in different soil types and the potential of these fungi to assimilate various nitrogen sources. So far we have found differences in ability to use nitrate and protein. We are in the process of constructing mycorrhizal associations using fungi with different nitrogen source preferences. This should enable us to gain a better understanding of the ecological significance of mycorrhization and nitrogen source utilisation in native Australian plants.
For further details see: Turnbull, M. H. Goodall, R. Stewart, G. R. (1995) The impact of mycorrhizal colonization upon nitrogen source utilization and metabolism in seedlings of Eucalyptus grandis Hill ex Maiden and Eucalyptus maculata Hook. Plant, Cell & Environment. 18: 1386-1394 A further publication has appeared that was in part funded by AFF. Root adaptation and nitrogen source acquisition in natural ecosystems: MH. Turnbull, S. Schmidt, P.D. Erskine, S. Richards & G.R. Stewart (1996) Tree Physiology 16, 941 948.