study of seed yield and seed macro elements content of three winter rapeseed varieties as affected by different nitrogen sources

in the first phase of this research, adaptability of winter rapeseed (brassica napus l.) varieties were investigated to select high yielding rapeseed cultivars. accordingly, two field experiments were performed in 2006-2007 and 2007-2008 cropping seasons at experimental field of agricultural and natural resources research center of markazi province, in arak, iran, in a randomized complete block design with three replications and using 15 winter rapeseed varieties. results showed that licord, modena and okapi varieties had superiority to other cultivars, respectively. at the second phase of this research, also, two field experiments were carried out during 2008-2009 and 2009-2010 cropping seasons at the same site, in order to evaluate the effects of nitrogen sources on seed yield and content of macro nutrient in seed of selected high yielding rapeseed varieties. experimental design was a factorial arrangement based on randomized complete block with three replications. three rapeseed varieties (v1 = okapi, v2 = modena and v3 = licord) and three sources of nitrogen based on 150 kgn/ha (n1 = compost of azolla, n2 = 50% compost of azolla plus 50% urea and n3 = urea) comprised the experimental factors. in this experiment, licord had the highest seed yield and seed content of sulphur. integrated nutrition system showed superiority to other treatments for seed yield and seed content of macro nutrients such as nitrogen, phosphorus and sulphur. but, the greatest seed content of potassium was observed in n1 treatment. results showed that integrated application of nitrogen sources increased yield and seed nutrients content.