Effect of fertilizers and cover crops on weed control and some quality characteristics of safflower (Carthamus tinctorius)

This experiment was carried out as factorial based on a randomized complete block design with three replications at the farm of Urumia University in 2013. Treatments included the cultivation of cover crops (red clover, matter pea, hairy vetch, bitter vetch) along the safflower rows and two control treatments [safflower planting with (control 1) and without weeds (control 2)] as the first factor and the application of organic manure and different amounts of chemical fertilizer systems (high, medium, and low) as the second factor. Results showed that hairy vetch and bitter vetch under different chemical fertilizer systems had the most effects on reducing the relative biomass of grasses and broad leaf weeds. In all the fertilizer systems, the highest seed phosphorus and potassium concentrations, grain and protein yield obtained from safflower plots without weeds or cover crops (control 1). Based on the results, by reducing the use of chemical fertilizers, the role of cover crops with increasing safflower seed nutrients became more pronounced. Use of hairy vetch as the cover crop in an organic fertilizer system increased the grain and protein yield of safflower by 74.83 and 79.15%, respectively, compared to plots without weed control (control 2) in a medium fertilizer system. Therefore, cover crops are appropriate tools for weed management in sustainable agricultural systems.