STUDIES ON THE OCCURANCE OF DIAZOTROPHS FROM THE RHIZOSPHERE OF LOWLAND RICE GROWN REGIONS OF TAMIL NADU

Abstract

A survey was conducted for the occurance of community diazotrophic populations, namely, Azospirillum, Pseudomonas sp. and Bacillus sp. from the rhizosphere of lowland rice was conducted at different locations of Tamilnadu. The survey revealed the ubiquitous occurance of diazotrophs in rice rhizosphere where the occurance Azospirillum brasilence was found to be at higher level followed by Pseudomonas sp. and Bacillus sp. A total numper 84 diazotrophic strains, namely 28 no. of Azospirillum, 28 no. of Pseudomonas sp. and 28 no. of Bacillus sp. were isolated. The results of the present study also revealed a marked variation in the community population of Azospirillum, Pseudomonas and Bacillus in the locations of Tamilnadu, observed. A range of 0.89 per cent to 1.41 per cent of Azospirillum, 1.12 per cent to 2.50 per cent of Pseudomonas and 0.51 per cent to 0.97 per cent of Bacillus to the total bacterial population was observed in the survey.