Effect of Reduced Doses of Foramsulfuron and Different Sowing Density on Corn (Zea mays L.) Yield and Weed Biomass

In order to study the effect of reduced doses of foramsulfuron and different sowing density on corn yield and weed biomass an experiment was conducted using split plot arrangement based on randomized complete block design with three replications at Research Field of Ferdowsi University of Mashhad، in 2011. Main plots were weed management methods including four levels of reduced doses of foramsulforun herbicide (0، 50، 75، 100% of recommended dose (2 l. ha-1، OD 22. 5%) and complete weeding (weed free treatment) and sub plots including four corn densities (5، 7، 9، 11 plant. m-2). Also، each plot was divided into two parts، the upper part of each plot was considered as unsprayed control (zero dose herbicide). Results showed that herbicide application and increasing corn density reduced weeds dry weight significantly (P≤0. 01). Minimums of weed dry maters (621. 42 g. m-2) related to treatment of reduced dose (75%) where reduced 48. 2% comparing with weedy check treatment. According to the results، herbicide application and increasing corn density comparing to the weedy check treatment affected corn biological and grain yield significantly (P≤0. 01). The differences between reduced and recommended doses with weed free control were significant but the corn yield in recommended dose with reduced doses treatments were not affected significantly. Also، these traits، increased significantly (P≤0. 01) by increasing corn density. As a result، increasing of corn density، through increasing corn competitive ability، can reduced damage of weeds and the amount of herbicide.