Three different types of nitrogen fixing bacteria viz, Azotobacter vinelandii, Bacillus polymyxa and Pseudomonas fluorescens were isolated from rhizosphere of field-grown sugarcane in Barak Valley, Assam. On an average highest number of diazotrophs was recorded in rainy season, which was followed by summer season. Lowest number of diazotrophs was observed in winter season. Nitrogenase activity of Azotobacter vinelandii, Bacillus polymyxa and Pseudomonas fluorescence was 403.05, 209.15, 107.80 (nM C2H2/h / mg protein) respectively. Data obtained in this work will hopefully contribute to future research aimed at developing reliable and effective sugarcane inoculants.
Diazotrophs, diversity, Sugarcane rhizosphere, nitrogenase activity
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