اثرات دزهای علفکش ایمازاتاپیر و تراکم علفهرز گاوپنبه بر عملکرد دانه سویا

To investigate the effects of Imazethapyr herbicide doses and velvetleaf weed densities on yield and biological yield of soybean, a field experiment was laid out at the research farm of Sari Agriculture Science and Natural Resources University in 2013. A factorial design based on randomized complete block design (RCBD) with three replicate was applied. Considered factors included 4 levels of velvetleaf densities (0, 5, 10, and 15 plant m-2) and 5 levels of Imazethapyr (0, 0.25, 0.5, 0.75, and 1 lit ha-1). Soybean yield showed significant differences (a= 0.01) between levels of weed density, herbicide dose and interactions of herbicide doses and weed density. Mean comparison showed that the highest and the lowest seed yield (2419 and 1096 kg ha-1, respectively), were obtained at weed free treatment and density of 15 velvetleaf plant m-2 at no herbicide plots. At no-herbicide treatment to 50% recommended herbicide dose, increasing weed density caused considerable seed yield reduction. Also highest and the lowest soybean biological yield (7376 and 3688 kg ha- 1, respectively), was obtained at density of 10 plant m-2 at 0.5 lit he-1 of herbicide and density of 15 plant m-2 at no herbicide plots. At no-herbicide treatment to 25% recommended herbicide dose, increasing weed density caused considerable soybean biological yield reduction.