Nitrogen fixation and growth of annual Medicago-Sinorhizobium associations at low temperature

Results demonstrated that responses of accessions depend on temperature, nitrogen and inoculated strain. Among the accessions tested, M. aculeata 5099 was more adapted to temperature and grew faster than the others at the lowest temperature. Strain M53 performed better with M. rigidula 716 than with M. aculeata 80 and strain M620 with M. aculeata 5099 than with M. aculeata 80 for yield and N nutrition of plants. M508 for M. aculeata 5099 and BZI for M. rigidula 716 leaded to more N fixed per plant. Nitrogen fixation in inoculated treatment of accession M. aculeata × M508 accounted for 88 and 78% of total plant N at 9 and 7 °C versus 49 and 51% for accession M. rigidula × M53. It was concluded that the selection of associations medics × Sinorhizobium is a promising way to improve yield and N2 fixation at low temperature in areas where N fertilization cannot be possible.