NITROGEN FIXING EFFICIENCY OF SOME INDIGENOUS RHIZOBIUM LEGUMINOSARUM ISOLATES FROM RED CLOVER (TRIFOLIUM PRATENSE L.) AND WHITE CLOVER (TRIFOLIUM REPENS L.) NODULES

The increasing demand for food leads to intensive agricultural practices which require a high input of synthetic fertilizer. The excess fertilizer ends up in aquatic ecosystems, leading to eutrophication and hypoxia. An alternative would be the use of microorganisms capable of incorporating atmospheric nitrogen into organic compounds. Nitrogen fixing bacteria, collectively known as rhizobia, establish symbiosis with leguminous plants in exchange for a carbon source, this relationship being beneficial for both parties. Commercial rhizobial strains have been used as crop inoculants to improve biomass production but the commercial strains are not as adapted to pedo-climatic conditions as the local, indigenous strains. We tested the nitrogen fixing efficiency of some native Rhizobium leguminosarum isolates from Romania, on biomass production of two clover species. Plants inoculated with the A2, R37 and R73 rhizobial isolates showed the highest amount of biomass accumulation.