response of corn (zea mays l.) growth characteristics to common lambsquarters (chenopodium album l.) competition

in order to investigate the effects of common lambsquarters (chenopodium album l.) competition on corn (zea mays l.) morphological and physiological characteristics, an experiment was conducted in 2005-2006 at the research station of agricultural faculty, ferdowsi university of mashhad, iran. the experimental design was split plot based on randomized complete block design (rcbd) with three replications. the emergence time was considered in three levels: emergence of the weed 14 days earlier, 7 days earlier and concurrent with corn, respectively, as main plots and density of weed at six levels: 0, 4, 8, 12, 16 and 20 plants per m2, respectively, as subplots. plant height, leaf area index (lai) and dry matter (dm) of corn decreased with earlier emerging and increasing density of the common lambsquarters. in contrast, lai and dry matter of common lambsquarters increased with earlier emerging especially at high densities. though, the increase in density of the weed resulted in reducing measured characteristics, but there was no difference between the processes of reduction in high densities of weed. totally, it can be stated that relative time of weed emergence compared to its density had maximum effect on corn plants and as the number of the earlier emergence days of common lambsquarters related to the corn increase, the competitive potential of corn reduces and an intense decrease is being observed in its growth and development.