عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In order to investigate the effect of crop row spacing and cocklebur (Xanthium strumarium) densities on yield and its components of two sesame cultivars, a Field experiment was conducted in 2009-2010 growing season at Research Farm of University of Agricultural Sciences and Natural Resources of Gorgan, Iran. The experiment was established as factorial arrangement using a randomized complete block design with three replications. The factors included different densities of cocklebur (0, 2, 4, 6 and 8 plant m-2) and two cultivars of sesame (Oltan, Yekta) and three sesame row spacings (35, 45 and 55 cm). The results showed that number of capsul per plant, seed per capsul, and 1000-seed weight were significantly affected by cocklebur density, sesame cultivars, and theirs interactions, but harvest index was only affected by weed density. Row spacing affected significantly on all yield components except of 1000-seed weight. grain yield and biomass of sesame cultivars reduced significantly with increasing cocklebure density and Oltan cultivar was less sensitive than Yekta cultivar. Grain yield was affected in competition with cocklebur more the biological yield. According to regression analysis, I parameter (yield reduction with entering the first weed) was estimated as 44.7, 43.91 and 46.39 for Oltan and about 48.68, 53.4 and 51.66 for Yekta in 35, 45 and 55 cm row spacing, respectively.