Seed oil content, oil yield and fatty acids composition of black mustard [Brassica nigra (L.) Koch] in response to fertilization and plant density

The cultivation of black mustard [Brassica nigra (L.) Koch] has recently become increasingly popular and there is a raising demand for its oil and seeds from the food, pharmaceutical, and cosmetic industries. A 2 -year experiment was conducted in a split-plot design with three replications, two main plots (plant densities: 46 and 76 plants m-2) and four sub-plots (fertilization treatments: control, urea with and without urease and nitrification inhibitors, and compost) to evaluate the fertilization and plant density effect on seed oil content, oil yield, and fatty acids composition of black mustard under Mediterranean environment. The seed yield, oil content and yield were positively influenced by the increase of available nitrogen and negatively by the increase of plant density, with their highest values recorded in the low-density and urea with double inhibitors. In response to the quality characteristics of seed oil, low-density compost application raised the quantities of polyunsaturated fatty acids (PUFA). In conclusion, plant densities higher than 46 plants m-2 result in lower seed yield, oil content and yield, while the inorganic fertilization effect, specifically with urea with double inhibitors, was equally important in seed and oil yield; however, when the seed and/or oil are used for their nutraceutical and medicinal value, the use of compost is recommended, resulting in a significant increase in PUFA content.