the influence of nitrogen and weed interference periods on corn

abstract in order to evaluate the influence of nitrogen application and duration of weed interference on corn (zea mays l.) yield and yield components, a field study was conducted in 2004 at the ferdowsi university of mashhad research field. the experimental design was a randomized complete block with a factorial treatment arrangement replicated three times. nitrogen fertilizer was applied at rates equivalent to 184 and 368 kg n ha-1. a quantitative series of treatments of both increasing duration of weed interference and length of weed-free period were included in each nitrogen level. results of this study showed that duration of weed interference had a significant effect on corn yield and yield components, reducing corn yield as duration of weed interference increased. increasing nitrogen rate had no significant effect on corn yield, but in two cases of weed interference (weed infested until 12 leaf stage and weed infestation throughout the season), increasing nitrogen resulted in decreased corn yield, likely due to the higher weed competition.