Modeling Herbicide Dose Effect and Common Cocklebur (Xanthium strumarium) Interference in Soybean (Glycin max)

Document Type : Research Paper

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Abstract

Field experiment was conducted to study the interaction between imazethapeyr dose and Xanthium strumarium density on soybean yield. Four densities of weed (0, 4, 8 and 12 plant.m-2) × 5 doses of herbicide (0, 25, 50, 75 and 100 g a. i. ha-1) was assigned in a factorial arrange of treatments with four replications. A combined model incorporated standard dose response curve and rectangular hyperbola competition model gave a good description for soybean yield. When no herbicide was applied, soybean yield was decreased by 58, 73 and 80% at densities of 4, 8 and 12 plant.m-2. Where the densities of common cocklebur was low (0 ,4 plant. m-2)  applying herbicide at half of the  recommended dose could save the yield by 90% however; with increasing weed densities to 8 and 12 plant.m-2, 20 and 30% yield loss was caused in soybean yield. No difference was found between herbicide application at 75 and 100 rate of the recommended dose.

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