Study of the amount and type of nitrogen source on sunflower yield and yield components in Markazi province

In order to investigate the quantity and source of nitrogen and nitrogen coated urea on yield and growing index in sunflower hybrids، an experiment was conducted in research farm of Agricultural Jahad Organization in Arak during 2006. The main goal of this research was determining the suitable quantity and kind of nitrogen application to reach the maximum grain yield and oil yield of two sunflower cultivars in climatic conditions of Arak as provincial center of Markazi province. The experiments was done with different treatments of nitrogen and nitrogen coated urea each in 3 levels (25، 50، 100 kg/ha) of recorded cultivar and Liza–R–M hybrid based on factorial experiment in RCB with four replications. Some of compared characteristics were considered as، plant height، hay yield weight، head diameter، disk seed weight، 1000 seed weight، seed yield، harvest index، oil percentage، oil yield and rate of crop growing. The result of experiment showed that application of different nitrogen levels had significant difference on the rate of growing but the oil percentage had no differences. The highest grain yield was related to record cultivar with average 3. 36 ton/ha and the treatment of 100 kg/ha nitrogen coated urea with average 3. 96 ton/ha. The comparison of different treatments showed the highest increase in the crop growth rate in treatment of 100 kg/ha nitrogen coated urea much more than the others.