Content of Biogenic Elements and Fatty Acid Composition of Fenugreek Seeds Cultivated under Different Conditions

Fenugreek (Trigonella foenum-graecum L.) is a medicinal plant that has been recognized for its numerous health benefits throughout the centuries. The species is a rich source of biogenic elements, and it has a favorable composition of fatty acids. This study evaluated the effect of agrotechnological factors on the chemical composition of fenugreek seeds. The experiments conducted in northeastern Poland had a fractional factorial design with 54 plots. A total of five agrotechnological factors were tested: seed inoculation with Rhizobium meliloti, sowing date, row spacing, weed control, and protection against fungal pathogens. The chemical composition of fenugreek seeds was influenced mainly by sowing date, row spacing and plant protection. Fenugreek seeds grown in north-eastern Poland contained 26.0% protein and 4.8% oil. Delayed sowing increased N content (9.2%) and decreased the content of P (8.8%), K (5.1%) and Mg (2.8%). An increase in row spacing from 15 cm to 45 cm promoted the accumulation of Fe (31%). Agrotechnological factors induced the greatest variations in the composition of saturated fatty acids (mean difference of up to 14.5%), followed by monounsaturated (up to 9.5%) and polyunsaturated fatty acids (up to 4.5%). Total unsaturated fatty acids accounted for 80% of the fatty acid profile, with a predominance of essential fatty acids in oil: linoleic acid (37.9%) and a-linolenic (28.2%) acid. Sowing date and weed control were responsible for up to 3.1%-4.5% of differences in concentrations of essential fatty acids between treatments.