The effect of various plant densities on competitiveness of corn with natural population of weeds

In order to study the effects of increasing corn plant densities on competitive ability of corn with natural weed populations in Khouzestan climate, a split plot based on randomized Complete Block design with four replications were conducted in 2011 in a field experiment station at Ramin Agricultural and Natural Resources, University of Mollasani, Ahvaz. Treatments included pure stands of corn at three densities (40000, 70000 and 100000 plants ha-1) and weed-interference period to v9 and v13 in any of plant densities (40000, 70000 and 100000 plants ha-1). The following results were observed that there was significantly difference between studied characters, grain yield, biological yield, harvest index, grain number per and row number per ear, grain number per row and 1000-grains weight among treatments. The studied characters were severely reduced by increasing the duration of weed interference after corn emergence. In addition, results showed that with corn plant increasing densities, corn plants tolerated the presence of weeds until v9 stage with approximately 6-15% in yield loss.