Production of phytohormones by the nitrogen fixing bacterium, azospirillum

Abstract

Azospiritium, the nitrogen fixing bacterium associated with the root system in pear! millet (Pennisetum americanum) has been studied for the phytohormone production. Both the wild types of Azospirillum and the drug resistant mutants produced phytohormones like indole acetic acid and gibberellin like substances. Addition of the precursor tryptophan and aerated conditions of incubation helped the production of more IAA and GA. The isolates varied in their ability to produce the phytohormones. Seeds of pearl millet inoculated with Azospirillum resulted in profuse root hairs and lateral root development. Moreover inoculation resulted increase in the vigour index of the plant.