The effect of sowing date, plant density and different levels of nitrogen on the growth traits and rate of essence in medicine safflower

To study the effect of sowing date، plant density and different levels of nitrogen on yield and the among of essence in spring safflower an experiment was done in research farm of Arak Islamic Azad University during 2010. Experiment was performed as factorial split plot based on RCBD with four replications. Treatments were selected as two sowing date (10th of May and 10th of June as delayed planting)، three different levels of nitrogen (46، 92 and 138 kg/ha based on used urea) and two plant density (400 and 800 thousand of plant/ha). The treatment sowed in 10th of May with 800 thousand plant/ha and 92 kg/ha nitrogen has the maximum essence by 267. 431 g/m2. The Minimum essence yield was found in treatment sowed in 10th June، 46 kg/ha nitrogen and 800 thousand plant/ha by 163. 54 g/m2. Maximum yield was related to trait with 10th May، 138 kg/ha nitrogen and 800 thousand plant/ha by 3101 kg/ha. Results showed that sowing date of 10th of May has better yield in Arak region in respect with delayed planting and using nitrogen can cause to increase essence..