عنوان مقاله [English]
To investigate the response of safflower agronomic characteristics to time, rate and method of nitrogen applications, an experiment was carried out at the research Field of Payaam Nour Arak University in Markazi province during 2011. A factorial arrangement of treatment in a randomized complete block design with three replications was used. Time of nitrogen treatment was with three levels (half in planting date + half in rosette stage), (half in rosette stage + half in stem elongation) and (half in stem elongation + half in boll forming stage), urea application was two levels (150 and 300 kg.ha-1) and method of application was with three levels (mixed with soil, used in irrigation water and foliar application). Each plot consisted of 4 rows, 5 m long with 50 cm between rows and 5 cm between plants on the rows. Results indicated that the effect of application time on the characteristics like: height of branch, number of sub-branches, number of seeds per m-2, number of seeds per plant, biological yield of bolls, seed yield of bolls, harvest index of bolls were significant. The effect of nitrogen treatment rates on branch height, number of sub-branches, number of seeds per m-2, number of seeds per plant, biological yield of boll, harvest index of boll, and nitrogen use efficiency were also significant. Mean nitrogen use efficiencies for foliar application was 63.27% and for soil mixed application was 6.86%. Thus, it seems that foliar application of urea not only decreases environmental but also increases nitrogen use efficiency.