Nigella sativa L. is a medicinal plant with extensive, nutritional, pharmaceutical, and health applications. Nowadays, reducing the application of chemical fertilizers (synthetic fertilizers) is one of the main goals of sustainable agriculture to allow the production of safe crops. Therefore, the combined effect of urea and biofertilizers was studied on the quantitative and qualitative traits of N. sativa L. in a randomized complete block design with 10 treatments and three replications. The treatments included control (no fertilization), U (100% chemical fertilizer as urea at 53.3 kg ha−1, Nb (Biofertilizer, Azotobacter vinelandii), Pb (Biofertilizer, Pantoea agglomerans and Pseudomonas putida), Kb (Biofertilizer, Bacillus spp.), NPKb (NPK, biofertilizer), Nb + 50% U, Pb + 50% U, Kb + 50%U and NPKb + 50% U. The NPK(b) + U50% was related to the highest quantity of plant height, branch diameter, capsule (follicle) number per plant, auxiliary branches, seed yield per plant, thousand-seed weight, essential oil content, total phenolic compounds, flavonoid content, DPPH free radical scavenging, nitric oxide (NO) radical scavenging, superoxide radical scavenging, chain-breaking activity, phosphorus content, and potassium content, along with U for the highest biological yield and (Pb) + U50% for the highest essential oil percentage which is close to (NPKb) + U50%. The lowest value was observed in all traits related to the control treatment except for branch diameter that was related to (NPKb). Hence, the application of (NPKb) + U50% as bio-chemical fertilizers improved N. sativa L. Traits, so it can be recommended.

The present study evaluated the effects of biofertilizers on qualitative and quantitative traits of Nigella sativa L. The experiment was conducted based on a randomized complete block design with 10 treatments and three replications. The treatments included control (no fertilization), U (100% chemical fertilizer as urea at 53.3 kg ha−1, Nb (Biofertilizer, Azotobacter vinelandii), Pb (Biofertilizer, Pantoea agglomerans and Pseudomonas putida), Kb (Biofertilizer, Bacillus spp.), NPKb (NPK combined biofertilizers), Nb + 50% U, Pb + 50% U, Kb + 50% U, and NPKb + 50% U. The highest oil percentage was 46.33 percent related to NPK(b) + U50%, and the highest oil yield was 466.43 kg/ha related to NPK(b) + U50%. The highest seed yield (1006.64 kg/ha) was observed in the plants treated with NPK(b) + U50%. The treatment of K(b) + U50% increased myristic acid by 0.35%. The NPK(b) + U50% treatment reduced palmitic, stearic, and linolenic acid by 11.3, 2.01, and 0.31%, respectively. The highest oleic acid (27.85%) and linoleic acid (56.6%) were obtained from the treatment of NPK(b) + U50%, respectively. The plants treated with NPK(b) + U50% showed the highest seed N percentage (%), P content (mg g−1) and K content (mg g−1). In general, NPK(b) + U50% is the best treatment in line with sustainable agriculture.