Response of yield, yield components and fatty acids profile of sunflower to spatial arrangement and different levels of nitrogen

To investigate the effect of different cultivation arrangements and levels of nitrogen on the yield, yield components and fatty acids profile of sunflower, this study was conducted as a split plot experiment in a randomized complete block design with three replications in 2021. Spatial arrangement in five levels (normal rectangle, wide rectangle, square, triangular, and mixed cultivation systems) as the main plots and the levels of nitrogen chemical fertilizer (urea) in three levels (application of 100%, 75%, and 50% of urea fertilizer requirement) were placed in sub-plots. The maximum dry weight of leaves and stems was obtained in the triangular planting arrangement at all three levels of nitrogen application. So that the triangular planting arrangement had a 30% increase in dry weight of leaves and stems compared to the wide rectangular planting arrangement. The normal rectangular cultivation treatment with 100% nitrogen application had the highest amount of palmitic acid fatty acid, and the mixed and triangular cultivation treatment with 50% nitrogen application had the highest percentage of stearic acid and oleic acid, respectively. While, the wide rectangular cultivation treatment with 75% nitrogen application had the highest linoleic acid compared to other treatments. In addition, the results showed that the yield, and yield components in the triangular system were more than the other investigated systems, so that by reducing the nitrogen consumption by 50% in this cultivation system, the yield did not have any significant difference with 100% urea application. Therefore, using the spatial arrangement of triangular cultivation is introduced as the best cultivation system for sunflower.