By forming a symbiotic connection, some bacteria fix atmospheric nitrogen in the root nodule of plants. Rhizobium infects legume trees for nodulation, while Frankia is an actinomycete recognized for forming actinorhizal symbioses with nonlegumes. Azospirillium, on the other hand, is a nitrogen-fixing symbiotic organism. The fungus known as vesicular arbuscular mycorrhizal (VAM) aid in the absorption of phosphorus by plants. The current research looked at these four bacteria. Frankia, Rhizobium, and Azospirillum were inoculated to Casuarina equisetifolia, Acacia nilotica, and Eucalyptus tereticornis, either individually or in combination with VAM. In comparison to the control, the inoculation resulted in a significant increase in biomass. In comparison to the control, Casuarina equisetifolia and Acacia nilotica produced more nodules with greater nodule dry mass and nodule nitrogenase activity. It is essential to note that in all three tree species, dual inoculation with Frankia VAM, Rhizobium VAM, and Azosprillum VAM produced greater output than single inoculation.