Two field experiments were conducted to evaluate effects of two endophytic bacterial strains (Azospirillum amazonense SHL70, Bacillus subtilisTAL4) together with different levels of inorganic nitrogen and phosphorus fertilizers on the growth and grain yield of high-yielding rice (cv. Ma Lam 213) cultivated on silty clay loam soils of Dong Hoa district and Tuy An district, Phu Yen province, Vietnam in Summer-Autumn 2014 cropping-season. The results of two field trials showed that bacterial inoculation in rice seeds (either SHL70 or TAL4 and especially mixture of SHL70 and TAL4) plus 60 kg N and 40 kg P₂O₅/ha having yield components and grain yield were not significant difference with those of rice only applying 120 kg N and 80 kg P₂O₅/ha without inoculation therefore both of bacteria strains provideds 50% biological nitrogen and available phosphorus quantity for high-yielding rice requirement, improvement of quality grain and soil fertility of Dong Hoa district and Tuy An district, Phu Yen province.

Keywords: Azospirillum amazonense, biological nitrogen fixation, Bacillus subtilis, grain yield, high-yielding rice, phosphate solubilization