Effect of sowing density and nitrogen rate on weeds biomass and some of agronomic traits of grain corn 640

To study effect of sowing density and nitrogen rate on weeds biomass and some of agronomic traits in grain corn 640 an experiment was conducted in 2013 in research field of Jihad-e- Keshacarzi of Khosroshahr in Nojedeh village in a randomized complete block design with three replications. Studied factors in this experiment were crop density (8, 10 and 12 plants per square meter) and nitrogen fertilizer rate (100, 200 and 300 kg ha-1). Results showed that increasing of density resulted in reduction of biomass of weeds to 27.2% and grain weight increasing in square meter (28.2%) and 300 grain weight. Nitrogen increased maize ear and wood diameter. Number of grains in ear row effected by 10 plants and 300 kg nitrogen ha-1 and showed the higher value (14.7%). It can be suggested that increasing corn density and using 300 kg ha-1 nitrogen fertilizer could be a procedure for decreasing reductions resulted from competitive weeds.