Selection of efficient Azospirillum isolates from rhizosphere and root samples of paddy using acetylene reduction assay (ARA)

Azospirillum is a known diazotroph fixes atmospheric nitrogen through biological process by having the vital enzyme nitrogenase. Studying the nitrogen fixation is a effective and fruitful tool to know the efficiency of bacterium on nitrogen fixation. In the present study about 20 isolates were isolated from 10 different locations of Namakkal district. Among the twenty isolates 10 isolates from rice rhizosphere soil and another ten isolates from rice root. All the twenty isolates were studies for n fixing efficiency through ARA assay, all the isolates recorded ARA activities, among the twenty different isolates, the isolates from root samples of rice recorded much significant values on ARA activity compared with the isolates from rice rhizosphere soil samples.