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 growthpromoting 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.