effect of various doses application of metribuzin herbicide and plant density on yield and physiological indices of wheat (triticum aestivum)

in order to survey the influence of metribuzin herbicide on physiological indices and yield of wheat, an experiment was conducted at experimental field of plant pest and disease research institute, karaj, iran during 2007. treatments were in factorial arrangement laid out in four randomized complete blocks. the factors investigated were three plant densities: 400, 500 and 600 plant.m-2 and metribuzin doses: 0, 0.2, 0.4, 0.6 and 0.8 kg.ha-1. the result showed that the highest physiological indices and grain yield were obsevered in densities of 500 plant.m-2 and in applications of 0.6 and 0.8 kg. ha-1. higher rates could be provided an acceptable level of weed control. plant density could provide good control on weed and could be decrease using herbicide too by decreasing of available light for weed. this strategy can reduce the peresure of selection in resistant weeds population.