Seed fixed oil content, oil yield, and fatty acids profile of Nigella sativa L. in response to fertilization and plant density

Abstract

The current study aimed to assess the impacts of fertilization and plant density on fixed oil content, oil yield, and fatty acids profile of Nigella sativa L. under Mediterranean environment. The 3-year experiment was set up in a split-plot design with three replications, two main plots (plant densities: 200 and 300 plants m-2) and four sub-plots (fertilization treatments: control, seaweed compost, farmyard manure and inorganic fertilizer). The seed yield, fixed oil content, as well as the fixed oil yield were positively affected by the increase of available nitrogen and negatively by the increase of plant density, with their highest values recorded in the low-density and inorganic fertilization. Regarding the composition in fatty acids, it was found that with the increase of plant density there was a decrease in saturated (SAFA: myristic, palmitic and stearic acid) and polyunsaturated (PUFA: linoleic, α-linolenic and eicosadenoic acid) fatty acids, while there was an increase in oleic acid which was the only monounsaturated fatty acid detected in fixed oil. In terms of fertilization, the organic fertilizers were the ones that contributed positively to the content of the respective fatty acid. As a conclusion, plant densities greater than 200 plants m-2 result in lower seed yield, fixed oil content and yield, whereas the effect of inorganic fertilization was equally important in seed and fixed oil yield; however, when the seed and/or its fixed oil are utilized for their high medicinal and nutritional value, the application of compost is indicated, resulting in a significant increase in the content of PUFAs, characterized for their beneficial effects on human health.