The reaction of quantitative and qualitative yield and fatty acids composition of three sunflower cultivars to different nitrogen fertilizer levels

In order to investigate the effect of different levels of nitrogen on some grain storage compounds and quantitative and qualitative yield of three sunflower cultivars, an experiment was carried out as split plots based on randomized complete block design with four replications in Dezful region during 2017-2018. In this research, four levels of nitrogen fertilizer (0, 60, 120 and 180 kg ha-1 N) were considered as the main factor and three sunflower cultivars (Ghasem, Record and Progress) as a sub factor. The results showed that increasing nitrogen consumption reduced the percentage of oil, percentage of stearic acid and linoleic acid percentage but, protein percentage, oleic acid and palmitic acid percentage increased significantly. There were significant differences between different cultivars in grain yield and oil content where Qasem cultivar had the highest grain yield (3920 kg ha-1) and oil (1860 kg ha-1) with the consumption of 180 kg ha-1 N. Also, the results indicated that the highest correlation of grain yield with the studied traits belonged to oil yield (r=0.97**) followed by protein content (r=0.85**) and the lowest to linoleic acid (r=-0.58*). In general, it can be stated that more nitrogen consumption has been effective in increasing the quality and quantity of sunflower and Qasim cultivar had a higher ability to absorb nitrogen in order to increase yield per unit area.