ICOM1 Abstract

DUNSTAN, WILLIAM A.1, NICHOLAS MALAJCZUK2 & BERNIE DELL1. 1School of Biological and Environmental Sciences, Murdoch University, Perth, W.A. 6150, Australia. 2CSIRO Forestry & Forest Products, CSIRO Centre for Mediterranean Agricultural Research, Private Bag P.O. Wembley, W.A. 6014, Australia. - Effects of selected bacteria on mycorrhizal development and growth of container grown Eucalyptus diversicolor seedlings. Eucalyptus diversicolor seedlings were co-inoculated with one of three isolates of two Laccaria spp. and an isolate of known Mycorrhization Helper Bacteria (MHB) or a bacterium isolated from Laccaria spp. sporocarps, or Eucalyptus marginata - L. fraterna ectomycorrhizas. No mycorrhizas were formed by L. laccata S238, a conifer mycorrhizal isolate. One MHB isolate, Bacillus subtilis Bbc6, (obtained from INRA, Champenoux, France), significantly reduced mycorrhization by L. laccata E766 but significantly increased mycorrhization by L. fraterna E710. One bacterium (Elf29), isolated from E. marginata - L. fraterna ectomycorrhizas, significantly increased mycorrhization by L. fraterna E710. In treatments with bacteria alone, one isolate significantly increased shoot dry weight. A significant increase in shoot dry weight was also observed in three bacterial treatments co-inoculated with L. laccata S238. Bacterial isolates that appeared to stimulate shoot growth did not increase mycorrhiza development.