effect of partitioning and application of urea on safflower yield and its components

to study the effect of urea application in safflower (carthamus tinctorius) and determination of effective traits on its yield, a factorial experiment based on randomized complete block design in three replications was conducted in tabriz, iran, during 2012. studied factors were urea rate levels as 100, 150 and 200 kg/ha and urea application times 100% in sowing time, 50% sowing time + 50% stem elongation, 25% sowing time + 50% stem elongation + 25% early flowering). application of 200 kg/haurea had the highest seed number per anthodium. number of secondary branches in 100 and 150 kg/ha urea application was more than 200 kg/ha. safflower fertilizing with 150 kg/ha urea as 25% sowing time + 50% stem elongation + 25% early flowering lead to seed production with higher thousand seed weight of 31.8 g. seed yield in fertilized plats with 150 kg/ha urea at 50% sowing time + 50% stem elongation was greater than other two urea doses. when plants fertilized with 150 kg/ha as 25% sowing time + 50% stem elongation + 25% early flowering or 50% sowing time + 50% stem elongation, oil yield was higher than 100% urea application in sowing time. the results of regression analysis revealed that thousand seed weight and number of secondary branches had higher positive effect on safflower yield. it is recommended to application of 75 kg/ha of urea in two or three parts of growth period for obtaining higher oil yield in safflower.