تاثیر تراکم بوته و نیتروژن بر رشد و عملکرد کلزا در رقابت با خردل وحشی(Sinapis arvensis)

In order to evaluate the effect of plant density and nitrogen on canola yield and growth under competition with wild mustard a field experiment was conducted at the research station of the College of Agriculture, Shiraz University at Bajgah in 2012. A split split plot design with four replications was used. Treatments included three plant densities (70, 80 and 90 plant m-2) and four nitrogen levels (0, 75, 150 and 225 kg N ha-1). Results revealed that in weedy condition with increasing plant density from 70 to 90 plant m-2 seed yield was increased significantly and among yield components, pod number plant-1, seed number per pod were increased significantly. Under weed free condition, with increasing nitrogen level from 0 to 225 kg N ha-1 seed yield was increased and in weedy condition, with increasing nitrogen level from 150 to 225 kg N ha-1 not only seed yield increasing was observed but also, weed dry weight was increased significantly. It seems that high levels of nitrogen weren’t able to diminish negative competition effects of weed on canola, however, this situation was able to increase weed competitive ability against canola with increasing weed height and dry matter, and was cause of seed yield reduction.