The effect of chemical and organic fertilizer application on growth, seed yield and seed oil content of blessed thistle (Cnicus benedictus L.)

This experiment was conducted to investigate the effect of applying different levels of vermicompost and nitrogen fertilizer and their combination on seed yield, seed protein, oil content, and fatty acids profile of the Blessed thistle. The experiment was arranged as a complete block design with three replications in 2018 and 2019 in the experimental field of the faculty of agriculture of Tarbiat Modares University, Tehran, Iran. Treatments consisted of (control (no fertilizer), 100% nitrogen fertilizer requirement, 75% nitrogen fertilizer requirement + 25% vermicompost, 50% nitrogen fertilizer requirement + 50% vermicompost, 25% nitrogen fertilizer requirement + 75% vermicompost and 100% vermicompost). The results showed that the highest biomass (10.32 ton ha-1) and plant height (100.2 cm) was obtained in the combination of 50% nitrogen requirement and vermicompost. The highest 1,000-seed weight (30.9 g), seed yield (1708.3 kg/ha), seed oil percentage (18.9%), and oil yield (323.52 kg/ha) were observed in 100% vermicompost treatment. The highest percentage of linoleic acid (66.7) and oleic acid (25.8) were observed respectively in the treatment of 100% vermicompost and 100% nitrogen fertilizer requirement, and the lowest in the treatment of 100% nitrogen (61.01% linoleic acid) and without Fertilizer consumption (control) (23.09% oleic acid). The results indicated that the vermicompost fertilizer treatments had a positive effect on the quantity and fatty acid composition of the blessed thistle seeds, the treatment required 50% nitrogen fertilizer + 50% vermicompost and for seed production, 100% vermicompost treatment is more suitable in the climatic conditions of the experimental site.