Evaluation of Competitiveness of Corn and Pigweed in Nitrogen Levels under Pigweed Densities by Corn Yield Converse Relations

ABSTRACT:To evaluate thecompetitiveness of corn and pigweed in different nitrogen levels under different pigweed density by means of converse relations of grain yield of mono corn plant, twoexperiments in split plot based on completely randomized blocks with three replications were conducted in 2010 and 2011 at the Islamic Azad University of Astara.Nitrogen in four levels of 0 (control), 100 (recommended nitrogen amount in the), 160 and 220 kg N.ha was the major factor; and the sub factor was density of redroot pigweed at four levels (0 (monoculture corn), 5, 10 and 20 plants per square meter). The resulting data were analyzed using SAS software, and the means comparison was done by Duncan test at P?5. The results showed that the converse of grain yield of mono corn plant was decreased under weed-free conditions with increasing nitrogen.In addition the converse of grain yield of mono corn plant was increased with weed density increase and correlation intensity of pigweed density was decreased with consumption of 0 up to 160 kg N.ha, but increased with the consumption of 220 kg N.ha.