This investigation was conducted during the two successive summer seasons of 2022 and  2023 to study the effect of numerous combined applications of mineral nitrogen fertilizer levels (N) as (NH₄)₂SO₄ and three different of wild type strains of Azotobacter chroococcum  (AZO1, AZO2, and AZO3) on growth, yield and quality of bottle gourd plants. It was found that the emergence percentage of bottle gourd seeds was improved after inoculation with AZO3 alone and the majority of combined treatments as compared to the recommended dose (100% N). Plants treated with AZO3 alone gave close results to those treated with 100% N and mixing AZO3 with different doses of N (25, 50, and 75%) made considerable increments in almost vegetative growth traits. Both single and combined treatments decreased significantly the number of male flowers and days taken for flowering initiation. In contrast, the number of female flowers was increased in plants treated with all tested combined treatments. The majority of combined treatments were superior to single treatments for improving all studied fruits, yield, and NPK contents in leaves especially those of mixtures (AZO3 + 50 and 75%N) which gave the best results as compared to other treatments. Finally, it could be concluded that to decrease the hazard effect of mineral fertilizers on environment and human health as well as improve growth, yield and quality of bottle gourd plants, it might be used (AZO3 and AZO1) bio-inoculates alone or in combination with low doses of nitrogen mineral fertilizers in bottle gourd fertilization programs.