Genotype-associated variation in essential oil and fixed oil composition and antioxidant potential of black cumin (Nigella sativa L.) grown under uniform field conditions

Genetic diversity is a major determinant of the chemical composition and functional quality of plant-derived essential oils and oils, particularly in species with food and nutraceutical applications. Black cumin ( Nigella sativa L.) provides essential oil (EO) and fixed oil of interest for food and nutraceutical applications, but compositional comparisons among origins are often confounded by growing environment. This study evaluated EO content and composition, fixed oil content and fatty-acid composition, and DPPH radical-scavenging activity in ten N. sativa genotypes grown under uniform field conditions in a randomized complete block design with three replications. EO constituents were quantified by gas chromatography-flame ionization detection (GC-FID) and identified by gas chromatography–mass spectrometry (GC-MS); fatty-acid methyl esters were analyzed by GC–FID. EO and fixed oil contents differed significantly among genotypes and ranged from 0.078 to 0.174% and 23.39 to 33.64%, respectively. Twenty-one EO constituents were identified; p-cymene (48.32–62.77%), α-thujene (8.23–26.15%), 1-Terpineol (2.98–7.80%), α-pinene (2.09–6.19%), and β-pinene (3.53–5.26%) predominated. Eleven fatty acids were identified, principally linoleic acid (61.17–63.54%), palmitic acid (14.76–15.57%), oleic acid (12.87–14.29%), stearic acid (3.23–3.84%), and eicosadienoic acid (3.22–3.69%). EO and fixed oil IC50 values ranged from 0.34 to 1.07 and 2.12 to 2.69 mg mL −1 , respectively. Thus, genotype background was associated with quantitative variation in oil yield, composition, and in-vitro antioxidant activity under the tested environment. These findings support germplasm selection for subsequent breeding and ingredient-standardization studies, but multi environment and food matrix validation are required.