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

Several strains of Bradyrhizobium, Mesorhizobium and Sinorhizobium strains were tested for their compatibility with an Australian acacia: Acacia holos ericea. All bacterial strains induced some nodule formation on roots. Howev er, the rhizobia which greatly increased the development of seedlings belon ged to the Bradyrhizobium genus. The root-knot nematode Meloidogyne javanic a, strongly inhibited the symbiosis with most of the rhizobial strains. The rhizobia had no effect on nematode multiplication except for bacterial str ain ORS 1020 where the final nematode population was higher than in the con trol treatment. The hypothesis concerning the interactions between nematode s and the nitrogen fixative process are discussed. Moreover, this investiga tion underlines the decreasing effect of nematodes on the potential benefit s that may result from growing A. holosericea inoculated with selected rhiz obial strains. (C) 2000 Editions scientifiques et medicales Elsevier SAS.