The experiment was carried out using two factors completely randomized experimental design with four replications per treatment. The first factor included three rice varieties (IR50404, MTL547 and MTL560) and second factor included five nitrogen sources [For control (no nitrogen), 0.2 g N/pot of Dau Trau Golden N 46A+ (urea nitrogen coated with Agrotain active element, content from 0.2 to 0.3 per cent), 0.1 g N/pot of Dau Trau Golden N 46A⁺ (urea nitrogen coated with Agrotain activeelement, content from 0.2 to 0.3 per cent) combined biofertilizers containing nitrogen-fixingbacterium Azospirillum lipoferum, 0,2 g N/pot urea nitrogen and 0,1 g N/pot urea nitrogen combined biofertilizers containing nitrogen-fixing bacterium Azospirillum lipoferum]. Results recorded as follows: 0,1 g N/pot (equivalent to 40 kg N/ha) of Dau Trau Golden N 46A⁺ combined biofertilizers containing nitrogen-fixing bacterium Azospirillum lipoferum on MTL560 which was the highest yielding (27,50 g/pot).