| In order to study the effects of wild mustard density on grain yield and yield components of canola cv. Hyola 401 under different rates of nitrogen fertilizer, a field experiment was conducted in 2011-2012. The layout was split-plot in a completely randomized block design and three replications. Main-plots included four levels of nitrogen (0, 70, 140 and 210 kg ha-1) and sub-plots consisted of different wild mustard densities (0, 6, 12, 18 and 24 plants m-2). Results showed at densities of 6, 12, 18 and 24 wild mustard.m-2, grain yield losses were 15.5%, 36.7%, 47.4% and 58.6%, respectively. Grain yield loss was due to reduction in number of grains per plant and 1000-grain weight. Agronomic N use efficiency (ANUE) of canola decreased as the weed density increased. The highest ANUE was obtained in 70 kgNha-1, without weed interference. The lowest ANUE was in 210 kgNha-1 and 24 wild mustard plant.m-2 treatment. Generally, application of 140 kgNha-1 lead to higher competitiveness and lower grain yield loss in canola compared with 0 kgNha-1, whereas, in 210 kgNha-1, the negative impact of 12 wild mustard.m-2 and above on canola grain yield, was higher than other N treatments. |
