weed control efficiency of wild safflower (carthamus oxyacanthus m. bieb) in replacement series technique of barley (hordeum vulgare l.) and common vetch (vicia sativa l.)

introduction in agronomy, natural outlook has been expressed in different forms which stable agriculture is an example. stable agriculture is ascribed to the authentic management of agricultural resources, which in addition to fulfilling the ever-changing needs of humans, maintains the health of environment and capacity of water and soil resources. application of herbicides, besides being costly, resulted in the selection of herbicide resistant weed species and has become an environmental contamination factor. however, reduction of herbicide consumption is one of the goals of modern agriculture, with several methods being suggested, including intercropping. in natural conditions of production, environment conservation of weed existence requires cost. one of the important preparations in weed control from the perspective of sustainable agriculture, is using intercropping system. the aim of this study was to determine the role of crop diversity on weed and crop production based on the beneficial effects of intercropping system than pure. materials and methods in order to study effects of mixed and sole cropping of barley with common vetch on their biologic yield and utilization indices, an experiment was conducted in agricultural college of the university of lorestan, during the growing season of 2013-2014 with 24 treatments using the method of rows replacement series technique by the randomized complete block design in a factorial arrangement with three replications. first factor included 6 levels of intercropping: sole cropping of common vetch (100%), 55-45 (common vetch-barley), 35-65, 45-55, 65-35 and sole cropping of barley and second factor included 4 levels of weed wild safflower, control, 10, 15 and 20 plants per m2. in this experiment wce, ler and cr were measured. the data were subjected to analysis of variance (anova) using mstat-c computer software. mean comparisons were performed using duncan’s multiple range test at two levels of significant 1% and 5%. results and discussion there was significant difference between minimum and maximum dry weight of weeds, the results showed that barley have important role in weed control wild safflower. therefore, weed control efficiency in 15 plant in m2 was higher than two 10 and 20 plant in m2. the lowest wce (161.27%) was found at 15-35-65 treatment, but, the highest wce (51.99) was obtained from 15-65-35 (wild safflower-common vetch-barley) treatment. computes showed that wce, in 15 plants of wild safflower/m2, was more than 10 and 20 p/m2. the reduction in weed population and biomass in intercropping systems with barley may be attributed to shading effect and competition stress created by the canopy. thus, result showed that reduction rate of common vetch in intercropping, with bearing compatibility power to weeds reduced ler. cr for common vetch intercropping component in comparison with barley in total treatments was>1. the highest cr, for vetch obtained from treatment 45-55-control (2.64) and for barley from seed ratio 65-35-control (1.83). conclusion the results in this study showed various seed rate had noticeable effect on forage yield, ler and weed control. in this experiment changing seed rate in two tested plants (barly- commen vetch) changed the number and weed species, as a result noticeable changing was created in their competitive power. result showed that seed rate (35% barley-65% common vetch) was better than other treatment, not only in use efficiency of environment, but also it had more dry forage yield. also, former seed rate had effective role in decreasing the weed biomass. this important result was related to reduced light penetrate at the bottom of cover crop and probably lack of competition in access to environmental resources was also affected. so using this seed density for mentioned area is recommended for reducing weed competition and improving the quality and quantity of dry forage. acknowledgments the authors gratefully acknowledge the teachers of college of agriculture of lorestan university, for their critical review of the manuscript.