effect of organic and inorganic nitrogen sources on quantitative and qualitative characteristics in three winter rapeseed cultivars in arak

in order to study the effects of organic and inorganic nitrogen sources on quantitative and qualitative characteristics of three winter rapeseed cultivars, a field experiment was carried out as factorial arrangement in complete block design with three replications in agricultural and natural resources research center of markazi province, arak, during 2008-2009 growing season. three rapeseed cultivars (okapi, modena and licord) and three sources of nitrogen (azocompost, urea and 50% azocompos plus 50% urea) comprised the experimental factors. azocompost fertilizer was utilized before sowing time and urea fertilizer was applied at three stages inclodings of sowing time, stem elongation and before flowering. results showed that rapeseed cultivars had significant differences for all traits. licord cultivar had the highest seed yield, 1000-seed weight, seeds per silique in secondary branches, biological and oil yield. also there was significant difference between nitrogen sources for all characteristics at 1% probability level. integrated nitrogen treatment showed superiority to other treatments for siliques per secondary branches, siliques per main branch, biological yield, seed yield and oil yield. the interaction effect between nitrogen sources and rapeseed cultivars was significant for all traits at 1% probability level. licord cultivar with integrated nitrogen treatment showed the highest biological yield, harvest index and seed yield.