Bio-organic fertilizers induce biochemical changes and affect seed oil fatty acids composition in black cumin (Nigella sativa Linn)

[Display omitted] •Mycorrhizae and rhizobacteria can improve the biochemical properties of black cumin.•Bio-organic fertilizers induce biochemical properties and fatty acid.•Nutritional profile significantly enhanced with biofertilizers application.•Appropriate soil conditions can lead to better production of medicinal plants. Appropriate soil conditions as a cultural practice are the basis of medicinal plant production. The experiment was carried out to investigate the effect of NPK, vermicompost (VC), Pseudomonas fluorescens (PF), Azotobacter chroococcum (AC), Azospirillum brasilense (AB), Glomus mosseae (AMF) on plant weight, antioxidant capacity and fatty acid (FA) profile of seed oil, and leaf nutrients of black cumin (Nigella sativa Linn) in 2018 and 2019. The results showed that dry weight in plants treated with VC (24.9 g and 28.8 g) or in AMF-inoculated plants (23.4 g and 27.8 g) was significantly higher compared with other treatments in 2018 and 2019, respectively. The highest (1.34 mg gallic acid (GA) g−1 oil) total phenolic content (TPC) and DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activity (86.8 %) was observed in plants treated with VC, and followed by AMF. The main fatty acid component was linoleic acid (51.92–55.46 %), followed by oleic acid (22.6–24.5 %) and palmitic acid (13.24–16.27 %). The saturated fatty acid (SFA) under NPK application (23.39 % and 24.21 % in 2018 and 2019) was higher than other experimental treatments. Monounsaturated fatty acid (MUFA) concentration in plants inoculated with AMF (25.15 % and 25.41 % in 2018 and 2019, respectively) or supplied with AB and PF was greater. The seed oil of black cumin contained the significant level of polyunsaturated fatty acid (PUFA), which its highest content was obtained at in plants treated with VC as 55.74 % and 55.79 % in 2018 and 2019, respectively. Sustainable agricultural practices are required to increase ecofriendly performance, by using soil micro-organisms, conserving the natural resource base for improved medicinal plant cultivation.