Synergistic Effect of Azospirillum and Silicate Solubilizing Bacteria on NPK Content and Uptake of Rice (Oryza sativa) Var. CR 1009

Rice (Oryza sativa L.), is one of the major staple foods consumed by 70% of the world’s population and occupies one-fifth of the total land covered under cereal crops. Rice is cultivated in 114 countries across the world with an area of 160.59 million hectares with a production of 742.54 million tonnes and average productivity of about 4.62 t ha^-1. The diazotroph Azospirillum is a well-known heterogenous group of bacteria that can be found in the rhizosphere, root surface or in association with roots of many cereal crops. Bacillus mucilaginosus, a silicate solubilizing bacterium, and a common soil bacteria and used as a model microorganism for research and the application of B. mucilaginosus on the rice plant as plant growth promoting bacteria increase the rice productivity growing under lowland condition. In the present study, Ten locations from Cuddalore district, Tamilnadu were selected and the rhizosphere soil samples of rice plant were collected and analyzed. Totally Ten isolates of Azospirillum and Silicate Solubilizing bacteria were isolated, characterized up to the species level. Based on the PGPR traits isolates of A. brasilense (AZS-5) and B. mucilaginosus(SSB-2) were selected and these strains studied were further used to test their efficiency on the NPK content and uptake of rice variety CR 1009 through inoculation. The growth and yield of rice were investigated with graded levels of NPK under pot culture experiment. The results revealed that, the inoculation of Azospirillum and SSB viz., Azospirillum brasilense (AZS-5) and Paenibacillus mucilaginosus (SSB-2) with T - 75%NPK₁₂A. brasilense + Paenibacillus mucilaginosus (AZS-5 + SSB-2) increased the N P K content(%)( 1.80, 0.32, 2.18), N P K uptake( mg plant^-1) (150.01, 152.50, 150.60)which was almost on par with T₁ – 100% control with applied plants. The present research paves way for the cultivation of rice crop var. CR 1009 with the minimized usage of chemical fertilizers to the extent of 25 percent.