Azospirillum sp. is an associative nitrogen fixing proteobacteria that fixes atmospheric nitrogen in loose association with plant roots, for all plant species. Azospirillum sp. converts atmospheric nitrogen through the process of biological nitrogen fixation into ammonium which can be easily absorbed by the plant roots and provides 30-50% of plant nitrogen requirements.
In addition to this, Azospirillum sp. produces plant growth promoting substances like vitamins and phytohormones which influence plant growth especially root development to a large extent.