Effects of some cover crops on weeds population and biomass in Sunflower (Helianthus annuus L.) field

In order to evaluate the effects of some cover crops on weed populations and biomass during sunflower growth, an experiment was done in 2012 at the research field of Tabriz University, Iran. The experimental design was a randomized complete block with nine treatments in three replications. Treatments included triticale, hairy vetch, rapeseed, triticale + hairy vetch, triticale + rapeseed, hairy vetch + rapeseed, application of trifluralin herbicide, and controls (weed infested and weed free without planting cover crop). Results indicated that total weed density was reduced 44.92 % in triticale + rapeseed treatment, but application of trifluralin caused 64.24 % reduction in total weed density in comparison with weed infested. However, in triticale + rapeseed treatment, total weed dry biomass was reduced 72.12 % compared with weed infested, so that this treatment was better than application of trifluralin. The use of cover crops as a strategy to reduce the damage of weeds and application of herbicide can be helpful