Liquid Bioinoculant of Endophytic (Azotobacter chroococcum) and Rhizospheric (Azotobacter vinelandii) Nitrogen Fixing Bacteriafor Rice Crop

Abstract

Nitrogen (N) is deprived in most of the world’s soil which would directly hamper the sustainability of crop production. More than 50% of applied chemical N-fertilizer is lost in rice field and also causes negative influences on soil health thereby affecting crop yield and nitrogen use efficiency. Nitrogen fixing microbes are one of the possible alternatives of chemical N. Azotobacter chroococcum Avi2, a native endophyte (less prone to environmental factors) has been explored as a potential diazotroph for rice crop. Avi2 was isolated from Swarna root and its endophytic nature has been proved through FRET-based technique. Further, in vitro and in vivo analyses of Avi2 were done in rice to prove its diazotrophic efficacy. Besides, A. vinelandii SRIAz3 (free living nitrogen fixer) was isolated from rice rhizosphere (var: Khandagiri), and its nitrogen fixing mechanism has been proved in vitro and in vivo conditions. Finally, liquid formulations of these two were developed after extensive systematic evaluation. Shelf life of the developed formulation is more than twelve months under ambient condition. Continuous evaluations of these formulations were conducted in 30 different locations of farmer’s field in Odisha, which revealed that it can save approximately 12-25% of chemical-N without compromising its yield. Chlorophyll imaging study also revealed the efficacy of Avi2 in terms of quantum yield of photosystem II (PSII). Besides subsidy given by Indian Government, input cost of nitrogenous fertilizers for sustainable rice production is too high which can bring down drastically through intervention of Avi2 and SRIAz3 and will help to enhance the farmers’ income.