Effects of Plant Density and Type of Fertilizer on Nutritional Quality of Flaxseed (Linum usitatissimum L.)

Flax (Linum usitatissimum L.) is a multipurpose crop known for its highly nutritious seeds. This study aimed to determine how plant density and fertilizer type influence the nutritional composition of flaxseed, addressing a gap in the literature where combined effects on seed quality have not been thoroughly evaluated. Two plant densities (D1, 500 plants m−2; D2, 300 plants m−2) and four fertilizers (control, C; inhibited urea, I; organic, O; and urea, U), were compared. According to the results, the interactions of these factors influenced most of the traits. The highest yields were reported at D1I. Organic fertilization improved protein (7%) and fat (28%) content and reduced fiber (46%) and carbohydrates. In contrast, inorganic fertilization increased fiber, NDF (10%) and ADF (8%) content. Mineral composition was also affected, with O and I increasing K, Mg, Fe and Cu by 31%, 6%, 14% and 24% for O and 48%, 1%, 17% and 18%, respectively, for I. The correlation matrix analysis revealed a positive relationship between protein and fat content, whereas both traits were negatively correlated with fiber and carbohydrates. Overall, optimized density and fertilizer can improve the quality of flaxseed, supporting its use as functional food and feed ingredient.