Pre-incubation of Sinorhizobium meliloti with Luteolin, Methyl jasmonate and Genistein Affecting Alfalfa (Medicago sativa L.) Growth, Nodulation and Nitrogen Fixation under Salt Stress Conditions

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Salinity is among important soil stresses adversely affecting the process of nitrogen (N) fixation in leguminous plants in different parts of the world. It has been indicated that salinity can inhibit the early stages of nodulation process between bacterium and the host plant including the exchange of signal molecules (nod gene inducers). There has not been any research regarding the effects of nod gene inducers on the growth of alfalfa inoculated with Sinorhizobium meliloti under saline conditions. A growth chamber experiment was conducted to determine the effects of pre-incubation of S. meliloti with effective inducers of nod genes Luteolin, Methyl jasmonate and Genistein on the growth and N-fixation of two different alfalfa (Medicago sativa L.) cultivars (Yazdi and Hamedani) under salt stress. Nod gene inducers increased alfalfa growth and N fixation under normal as well as under salt stressed conditions. Yazdi cultivar showed to be more tolerant to salinity than Hamedani with a higher growth rate and N fixation. Luteolin was the most effective nod gene inducer on plant growth and N fixation under normal and as well under salt stressed conditions. The results suggest that pre-incubation of S. meliloti with effective nod gene inducers can improve alfalfa growth and N fixation under salinity stress.