effect of planting pattern and herbicide application on corn (zea mays l.) grain yield and weeds control

in order to study the effect of planting pattern and herbicide application on corn (zea mays l.) grain yield and weeds control, an experiment was carried out in 2007 at varamin research station of plant protection research institute. the experimental design was a randomized complete block in a split plot arrangement with 4 replications. experimental factors consisted of planting patterns at 4 levels were including one row planting on each ridge with recommended density, two rows planting on each ridge with recommended density, %25 and %50 more than recommended density in main plot and herbicide at 5 levels were including atrazin 0/8 ai kg ha-1 plus eptc 3/28 ai kg ha-1, atrazin 0/8 ai kg ha-1 a plus eptc 4/10 ai kg ha-1, atrazin 0/8 ai kg ha-1 plus eptc 4/92 ai kg ha-1, atrazin 0/8 ai kg ha-1 plus allachlor 2/4 ai kg ha-1, eptc 4/92 ai kg ha-1 in subplot. weed-free and weedy controls were added to treatments. results indicated that altering planting pattern to two rows planting with 25 and 50% more than recommended density significantly increased grain yield. altering palnting pattern to two rows planting also reduced weeds density and dry weight, and two rows planting on each ridge with %25 more than recommended density showed the lowest weeds density and dry weight. in different planting pattern atrazin 0/8 ai kg ha-1 plus eptc 4/92 ai kg ha-1 and atrazin 0/8 ai kg ha-1 plus eptc 4/10 ai kg ha-1 treatments had the lowest weeds density and dry weight, respectively. grain yield of herbicide treatments except weedy control had no significant difference in comparison with weed-free control. therefore by using reduced rates of herbicides can decrease herbicide application. therefore, two rows planting on each ridge with %25 more than recommended density (92,500 plants ha-1) and atrazin 0/8 ai kg ha-1 plus eptc 4/10 ai kg ha-1 are recommended for weed management in corn field.