Inoculation Effects of Standard and Native Rhizobium meliloti on Growth of Alfalfa (Medicago sativa) Under the SO2 Pollution

In this study, effects of Rhizobium on alfalfa plant growth under the SO2 pollution were evaluated 35 days plants (non-inoculated and inoculated with native or standard Rhizobium) exposed to the different concentration of SO2 (0, 0.5, 1, 1.5 and 2ppm) for 6 consecutive days for 2 hours per day. Results indicated significant decrease of Leaf area, stem length, root depth and fresh and dry weight of leaf, stem and root under high concentration of SO2. Number of leaves at all concentrations showed no significant change. Inoculation of alfalfa with Rhizobium significantly reduced the negative effects of high concentration of SO2. In this study, positive effects of native bacteria were impressive. The results indicate the harmful effects of high concentrations of SO2 pollution on growth of plants and the positive effects of bacterial inoculation on resistance to air SO2 pollution stress.