estimation of corn yield loss as affected by single or binary competition with common cocklebur and jimsonweed using weed density empirical models

field experiments were conducted to determine the influence of single and multispecies competition of common cocklebur (xanthium strumarium l.) and jimsonweed (datura stramonium l.) on corn yield and further the competitive abilities of these weeds .common cocklebur and jimsonweed were established at selected densities within 15 cm on either side of the corn row. common cocklebur and jimsonweed seeds were sown concurrently with corn. corn yield losses in the conditions of single and multispecies weed competition were estimated from empirical equations based on the cousens(1985) hyperbolic crop yield model. the results revealed that common cocklebur was more competitive than jimsonweed across all situations. in the mixed weed population plots including jimsonweed, common cocklebur and corn, while common cocklebur was assigned a competitive index of 1 on a scale from 0 to 1, the competitive ability of jimson-weed was recorded as 0.25 of common cocklebur. in the case of single weed population plots, one common cocklebur plant had 1.40 times a higher ability to reduce corn seed production as compared to jimsonweed.the results of this study, suggest that different weeds competition coefficients must be estimated from mixed weed population experiments.