Population dynamics and nitrogen fixation by diazotrophic bacteria in the rhizosphere of foxtail millet

The rhizosphere soil samples of foxtail millet were examined following conventional methods of isolation for populations of Azospirillum spp. and other diazotrophic bacteria, and compared with non-rhizosphere samples. Outof 45 isolates of non-symbiotic bacteria from the rhizosphere, only 15 were found to be diazotrophic. Positive rhizosphere effect on population density and nitrogen-fixing ability of selected non-symbiotic diazotrophs as well as associative symbiotic azospirilla was clearly evident.