Investigation of Drought Stress and Nitrogen Application Rate on Corn-Redroot Pigweed Competition Using Replacement Series Experiments

Water and nitrogen are the most important factors in plant competition. Since of nitrogen uptake by plants depend on water mass flow, and competition for nitrogen is depend to water availability in soil. In order to study the effect of drought stress and nitrogen application rate on corn-redroot pigweed interaction, a factorial experiment was conducted under greenhouse condition based on replacement series method in which different planting ratios of pigweed and maize component of 0:100, 25:75, 50:50, 75:25 and 100:0 pigweed: corn to corn teaseling stage in 1388 year at Faculty of Agriculture, Ferdowsi University of Mashhad research greenhouse. Treatments included soil water availability in soil at 2 levels (25 and 50 FC) and nitrogen application rate at 3 levels (0, 200 and 400 kg per hectare). Results showed that both corn and pigweed dry mater increased significantly (p≤0.05) with increasing nitrogen application rate in normal soil water condition. It also enhanced corn competitive ability with pigweed. But drought stress decreased both plants dry mater production of both corn and pigweed with nitrogen application. It also had not any advantage for corn yield.