Evaluating of Physiological Indices of Weed Species at Different Density on Corn (Zea mays L.) Growth

Crop density is one of the usage tools in sustainable agriculture to carry out integrated weed management. Weed species response varied according to diversity and density of species in agricultural ecosystems. This study was conducted in research field of Ferdowsi University of Mashhad، Iran. Four levels of corn densities (5، 6، 7 and 9 plant m-2) and four levels of species diversity were used including complete control، broad leaved control (corn and narrow leaves)، grass control (corn and broad leaves) and without control (corn، broadleaves and grass weeds) by weeding. All species sampling were done at five stages from 42 days after planting up to the end of growth period. Crop growth rate، total dry matter of weed (TDMw) and total dry matter of corn (TDMc) were measured. Results showed that TDMc was minimum at 9 and 5 plant m-2 in the early growth period، while it was highest at 9 plant m-2 by the end of the growth period. Also، TDMc increased with increasing density in the weed free control، but (TDMc) decreased about 46% in compare with complete control. The same trends were observed for CGR. It was found that broad leaves weeds were more effective than narrow leaves (causing 60 and 34% lower CGR reduction، respectively) on corn growth.