Effects of the root-knot nematode Meloidogyne java']javanica on the symbiotic relationships between different strains of Rhizobia and Acacia holosericea (A Cunn. ex G. Don)

Several strains of Bradyrhizobium, Mesorhizobium and Sinorhizobium strains were tested for their compatibility with an Australian acacia: Acacia holosericea. All bacterial strains induced some nodule formation on roots. However, the rhizobia which greatly increased the development of seedlings belonged to the Bradyrhizobium genus. The root-knot nematode Meloidogyne javanica, strongly inhibited the symbiosis with most of the rhizobial strains. The rhizobia had no effect on nematode multiplication except for bacterial strain ORS 1020 where the final nematode population was higher than in the control treatment. The hypothesis concerning the interactions between nematodes and the nitrogen fixative process are discussed. Moreover, this investigation underlines the decreasing effect of nematodes on the potential benefits that may result from growing A. holosericea inoculated with selected rhizobial strains. (C) 2000 Editions scientifiques et medicales Elsevier SAS.