ارزیابی اقتصادی کشت مخلوط باقلا (Vicia faba L.) با ذرت (Zea mays L.) براساس شاخص مجموع ارزش نسبی و کاهش رشد علف های هرز

The chemical control of weeds raises serious concerns about food safety and environmental quality, which have necessitated the need for non chemical weed management techniques such as intercropping. Intercropping can suppress weeds and reduce the use of herbicides in production systems. Therefore, the objective of this work was to evaluate the effects of intercropping of faba bean and maize, as well as hand-weeding on maize grain yield and total grain yield. The experiment was carried out during growing season of 2010 as a randomized complete block design with three replications at the Agricultural Research Station, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran. Sole cropping of maize with weed control (MWF), sole cropping of maize without weed control (MWI), intercropping of 15% faba bean+maize (M+15%F), 30% faba bean+maize (M+30%F), 45% faba bean+maize (M+45%F)  and sole cropping of faba bean were the experimental treatments. Weed biomass and density were affected by treatments. With increasing faba bean density in the intercropping treatments, weed biomass and density decreased significantly from 85 plants and 310 g m-2 for MWI treatment to 22 plants and 63 g m-2 for M+45%F treatment, respectively. The greatest number of seed row per ear, seed number per ear and grain and biological yields (8033 and 17933 kg ha-1, respectively) were achieved at MWF treatment and the smallest values for these attributes were revealed at MWI treatment. There was no significant difference between MWF and M+45%F treatments for total grain yield (i.e. grain yield of maize + faba bean). Sole cropping of faba bean led to the greatest yield components and grain and biological yields. With increasing faba bean density in intercropping treatments, above mentioned traits (except number of pods per plant) were increased significantly. The great values for weed control efficiency (73%) and total relative value (1.14) were achieved at M+45%F treatment. Results of this experiment indicated that additive intercropping of faba bean (especially with a high planting density) as a companion crop with maize may, potentially, lead to sufficient weed suppression concomitant to an acceptable level of grain yield.