Four Frankia strains were used to inoculate three Casuarina species in sterilized and unsterilized soils. Plants were analyzed for their growth performance as well as their enzymatic activities after three months of inoculation. Catalase, lipid peroxidation (malondialdehyde), free amino acids, and proline were measured for the treated plants after three months of inoculation. Only nodulation and plant performance were determined after three, six, and nine months of inoculation. The magnitude of plant performance was as follows: uninoculated plants in unsterilized soil ≥ inoculated plants in unsterilized soil > inoculated plants in sterilized soil. The indigenous Frankia populations may be more adapted to benefit from the intact soil biota found in the unsterilized soils than the introduced Frankia strains except in few treatments. The increase in catalase (CAT) and decrease in malondialdehyde (MDA) and proline content of plants in unsterilized soil indicate that indigenous Frankia, in combination with other accompanying microorganisms, are more beneficial for plant performance. Soil biotic community may produce the required factors for plant protection and successful growth conditions, in combination with the indigenous infective and effective Frankia strains.