Effect of maize (Zea mays L.) plant density on agronomic characteristics in competition with redroot pigweed (Amaranthus retroflexus L.)

To study the effects of maize plant density on agronomic characteristics in competition with redroot pigweed (Amaranthus retroflexus L.), a factorial experiment based on randomized complete block design with three replications was carried out at the research field of agricultural and natural resources research center of Ardabil, Moghan, in 2012. The experimental factors were maize plant density at four levels (70000, 75000, 80000 and 85000 plant/ha) and redroot pigweed at four plant density (0, 4, 8 and 12 plant/m per row). The traits related to corn and redroot pigweed performance were measured. Results showed that the highest grain yield of corn (11.88 t.ha-1) was obtained from plant density of 80000 plants.ha-1. Generally, the presence of redroot pigweed decreased the grain yield of corn. This pattern of reducing of corn grain yield in competition with redroot pigweed was also observed at the high density of corn hybrid. Nevertheless, the highest corn grain yield obtained at the high plant density of corn even when redroot pigweed density was too high. It seems that selecting of optimum corn plant density will produce satisfied grain yield at the presence of redroot pigweed.