effect of wild mustard (sinapis arvensis) competition and nitrogen levels on

to investigate the effect of wild mustard plant density and nitrogen fertilizer on morphological characters, yield and yield components of canola a split-plot experiment based on a randomized complete block design with 3 replications was carried out in bu-ali sina university of hamedan, in 2009. 4 levels of nitrogen fertilization (100, 150, 200 and 250 kgn h-1) were assigned to main-plots and plant density of wild mustard at 5 levels (0, 4, 8, 16 and 32 plants m-2) to the sub-plots. results showed that the effects of wild mustard competition on yield and components of canola was significant. 32 plants m-2 of wild mustard reduced grain and biologic yield, number of pod per plant, number of seed per pod and 1000seed weight about 28.7, 30, 40.9, 22.2 and 16 percent respectively. with more nitrogen application, number of pod per plant, number of seed per pod, 1000seed weight and grain yield was increased. by increasing nitrogen from 100 to 250 kg ha-1, grain yield was increased more than 53 percent. increasing density of wild mustard significantly reduced all above mentioned morphological and qualitative characters, except protein percentage. by increasing nitrogen fertilizer, plant height, number of branches per plant, pod length, oil yield and protein percentage of canola were increased significantly. overall nevertheless negative effect of weed on canola yield, seems that the application 200 kgn/ha in addition to increasing grain yield and canola oil, had less decline in weed interference.