Plant Growth Promotion Potential of Azotobacter Chroococcum on Growth, Biomass, Leaf Area Index and Yield Parameters of Aman Rice in Tripura.

Field experiment was conducted to assess plant growth promotion potential of Azotobacter chroococcum on aman rice in Tripura in rainy autumn season (Kharif – Aman, July - Nov) in 2008. The test variety cv NDR – 359 was inoculated with Azotobacter chroococcum. Split plot experimental design with 20 treatments and 3 replications was carried out. Two factors viz. four levels of urea N (20, 40, 60 and 80 kg h⁻¹) and three forms of inoculation (seed inoculation, root dipping and basal application) were applied. Both individually and in integration with different levels of urea N, the Azotobacter chroococcum substantially increased growth parameters, biomass, leaf area index (LAI) and yield parameters. The finding showed potentiality of Azotobacter chroococcum to save 20 kg N ha⁻¹. Basal application of Azotobacter chroococcum was most effective followed by inoculation in the form of root dipping of rice seedlings.