The effect of weed interference and weedfree on yield and yield components of corn (Zea mays) in Hamedan

In order to determine the response of yield and yield components of corn to weed interference and weedfree periods an experiment was conducted in Agricultural faculty of Hamedan in 2008. This experiment was a factorial experiment based on a randomized complete bloke design with three replications and twelve treatments. The treatments of experimental consisted of six initial weed-free periods in which plots were kept free of weeds for 0, 15, 25, 35, 45 and 55 days after crop emergence, and then weeds were allowed to grow until harvest and six initial weed-infested periods in which, weeds were allowed to grow for 0, 15, 25, 35, 45, and 55, after which the plots were kept free of weeds until harvest. Yield, yield components and total dry matter were determined at harvest. The effect of interference and weedfree of weeds on total dry matter, harvest index, number of kernel per rows, grain yield, were very significant but The effect of interference and weedfree of weeds on number of rows per ear were not significant. The effect of interference period of weeds on weight of 1000 kernel was significant but the effect of weedfree period was not significant.