عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In order to study the effect of mallow weed competition and nitrogen (N) rates on grain yield and yield components of wheat cv. Chamran, a field experiment was conducted in 2009. The experiment was designed as a split-plot with three replications and additive series. The N application rates were assigned in the main-plots (50, 100, 150 and 200 kg.N.ha-1) and sub-plots consisted of target common mallow (Mava spp) densities (0, 5, 10, 15 and 20 plant.m-2). Result indicated that, the effect of nitrogen (N) treatments, weed density (WD) and N×WD on grain yield (GY) was significant in 1% probability level. Grain yield decreased significantly as the WD increased. Grain yield reduction in high weed densities was due to lower spike per square meter (Sm-2), grain per spike (GN) and 1000-grain weight. Under the density of 20 mallow plant.m-2, GY, Sm-2, GN, spikelet per spike and 1000-grain weight losses was 27%, 15%, 10%, 6% and 6%, respectively. Wheat grain yield loss attributed to mallow weed ranged from 7 to 32% at 50 kg.N.ha-1 to 9 to 21.8% at 200 kg. N. ha-1. The highest and the lowest weed individual dry weight was belonged to 200 and 50 kg.N.ha-1, respectively. Agronomic N efficiency (ANE) of wheat decreased as the weed density increased. Wheat grain yield in mallow infected plot generally enhanced with N fertilization, while the density of mallow weed increased. Wheat competitiveness, GY and ANE were improved as N rate increased.