Associative Effect of Arbuscular Mycorrhizal Fungi And Rhizobium on Plant Growth and Biological Control of Charcoal Rot in Green Gram [Vigna Radiata L. (Wilczek)]

156The present study was carried out in pot experiments to assess the response of green gram [Vigna radiata (L.) Wilczek] to the synergistic effects of treatments with predominantly occurring indigenous arbuscular mycorrhizal (AM) fungi (Glomus constrictum Trappe) and Rhizobium treated individually and in combination with or without the pathogen on the extent of nodulation, nodule dry weight, nodule nitrogen, mycorrhizal root colonization, plant growth, biomass production, nutrient uptake (NPK) into whole plant at 45 and 75 days old crop, grain yield, and suppression of the charcoal rot causing pathogen Macrophomina phaseolina. The experiment was repeated twice. The plants inoculated with Glomus constrictum significantly increased the shoot and root heights, and their fresh and dry weights. In dual inoculated plants, maximum growth parameters were recorded compared with plants that were treated with AMF or Rhizobium singly. The same trend was observed in the plants inoculated in combination with pathogen. The grain yield of the plants inoculated with AMF Glomus constrictum and Rhizobium alone or in combination was significantly greater than the uninoculated control plants. Mycorrhizal inoculated plants significantly reduced the disease incidence from 76.36 and 84.7% to 19.86 and 16.90% and increased the per cent disease control to 104.95 and 98.11% in experiment I and II, respectively. However, the plants co-inoculated with Rhizobium and G. constrictum were more tolerant to the fungal root rot pathogen as evidenced by a further reduction in the disease incidence by 13.10 and 12.60% and the per cent disease control increased to 113.80 and 103.19%, respectively. Hence, the synergistic effect of AM fungus Glomus constrictum and Rhizobium is beneficial to green gram for its increased nodulation, improved plant growth, biomass production, mycorrhizal root infection, and mobilized more N, P, and K compared with the control plants or those inoculated with the pathogen.