Salt stress extremely disrupts the growth and developments of plants, whereas nutrients play a vital role in regulating plant responses to salinity stress. Bacteria is attracting increasing attention in recent years as a potential soil amendment under stress condition. This study addressed the use of salt tolerant strains (three strain) of Sinorhizobium meliloti to mitigate salt-stressed soil (7.34 dS m-1) and evaluated the levels of some nutrients in alfalfa (Medicago sativa L.) ecotypes (Kara yonje, Hamedani and Malek kandi). All of the Sinorhizobium meliloti strains under the salt stress, improved the forage yield in ecotype of Hamedani. In ecotype of Malek kandi, inoculation of seeds by strains 1 and 3 increased the dry weight of forage in compared to the non-inoculated crops, strain 2 did not show a tangible effect on forage yield. The most beneficial effect of Sinorhizobium meliloti on rising fresh and dry weights of alfalfa ecotypes occurred in ecotype of Hamedani with strain 2. Inoculation of alfalfa ecotypes by Sinorhizobium meliloti exposed various results depends to ecotypes, but in general in all of the ecotypes, Sinorhizobium meliloti improved the manganese content in plant tissues. This nutrient showed a significant correlation with alfalfa growth under salt stress.
