Tomato seeds and seedlings were inoculated by using non-symbiotic N₂-fixers Azospirillum brasilense and Azotobacter chroococcum to investigate the biofertilization influence on dehydrogenase activity, plant growth-promoting bacterial population, total nitrogen, phosphorus and potassium in soil. Fruits physical characteristics and percentage of total phenoles and indoles in fruits were also determined. Moreover, disease incidence of damping-off, in the presence of Fusarium oxysporum pathogen in the presence of biofertilizers were evaluated. Obtained data showed that, inoculation of seedlings (seeds+ seeding roots) gave the highest values of dehydrogenase activity, azospirilla and azotobacters proliferation, fruits quality and reduction of disease incidence. Also, results revealed that mixed inoculation of non-symbiotic N₂-fixers increased all tested parameters and reduced disease incidence than single inoculation of either seed inoculation or seedling inoculation by diazotrophs.