Potential of commercial rhizobial strains for new and existing perennial pasture legume cultivars on the NSW Tablelands

Abstract

Key findings •• Sites with a history of inoculation might have competitive populations of rhizobia with variable effectiveness for a given host. •• Some commercial inoculants for perennial legumes suited to the NSW tablelands can form root nodules with more than one legume species, and in some cases this can compromise nitrogen fixing. •• Within legume species, some cultivars formed effective root nodules with certain rhizobial strains, while others did not. •• Most of the rhizobial strains in nodules correlated with the commercial inoculant used before sowing. However, the persistence of some these rhizobial species is likely to be influenced by acidic soils and high exchangeable aluminium at some sites. •• Our results suggest: •• Where a history of annual subclover (and commercial inoculant WSM1325) is common, perennial legume cultivars with a capacity to form an effective symbiosis with the rhizobial strain WSM1325 might be desirable. •• Select pasture mixes with similar rhizobial strain requirements and inoculate accordingly. •• Where multiple hosts are sown together, ensure legume seeds are inoculated with the most effective rhizobia strain separately, before sowing.