Tolerance to salinity of diazotrophic bacteriaand their host species could increase plant growth and sustainability in salt stressed soils. Twelve diazotrophic bacteria strains were studied regarding their tolerance to different NaCl concentrations in 79 and LB media. More tolerant (30 g L-1) strains in 79 medium were: the fast growers BR 6806 and BR 4007, isolated from northeast Brazil, UFLA 03-51 and UFLA 03-65, and slow growing strain UFLA03-84, being these last three isolated from Amazon region. These strains were among the most salt tolerant in LB medium. The high salt tolerance of strain UFLA 03-84, as well as its highest efficiency (biological nitrogen fixation) in cowpea symbiosis (Vigna unguiculata), indicates it can be assayed as inoculant to improve yields of this species at saline soils. Media 79 and LB were efficient to evaluate relative tolerance of rhizobia to NaCl, however 79 medium is more suitable as it allows growth of all strains.
rhizobia; NaCl; stresses; Vigna unguiculata