Effect of time interference natural population weeds and plant density on some growth indices, yield and yield component of Corn (Zea mays L.)

In order to evaluate the interference effect natural population weeds and plant density, an experiment with Randomized Complete Block design in factorial arrangement with 4 replications was conducted in 2006 in a field experiment at Ramin Agricultural and Natural Resources University, Khouzestan. Treatments included two factor, plant density of corn at three levels (4, 7 and 10 plants m-2) and weed interference at three levels (no interference as pure stands, interference to v9 and interference to v13). Results indicated that at optimum plant density (7 plants m-2), corn can by competitiveness increase own weeds interference decreased. Never less weeds caused of corn dry matter accumulation, crop growth rate, leaf area index, grain yield, grain number per ear and row number per ear decreased. Meanwhile weeds interfere caused to least of dry matter accumulation, crop growth rate, leaf area index and grain yield got from the treatments weeds competition to v13 in any of corn densities. In addition, in these experiments characterized that with corn density increasing on weeds infested treatments, corn tolerated weeds with yield loss till v9 stage (approximately 5-15% and 40 days after planting), while corn yield decreased with increasing duration of weed interference to v13 stage and harvesting (full season weed infestation), and decreased with increasing duration of weed control (pure stands).