effects of application time of chevalier herbicide and mixture of illoxan with granstar on wheat and weed in ahwaz

in order to study effects of application time of chevalier herbicide and integrate of illoxan with granstar on wheat and weed inahwaz, an experiment was conducted in ramin agriculture and natural resources university during 2007-2008, in split plot design by randomized complete blocks design with four replications. experimental factors was chevalier and integrate of granstar and illoxan herbicides were arranged in main plots and time of application including five growth stages (three-leaf, end of tillerring, mid of stem elongation, spike appearance, and three-leaf+stem elongation), and without weeding and complete control of weed were arranged in subplots. the results of variance analysis showed that type of herbicide had not any significant effect on measured traits, but time of application had significant effect on weed control, yield and yield components of wheat. also, interaction effect of herbicide type and time of application was not significant. mean comparisons showed that delay in application of herbicide decreased herbicide efficiency, therefore, herbicide application in spike appearance caused to decrease in most traits of wheat. highest wheat yield and lowest weed dry matter were produced with herbicide application in 3-leaf stage and 3-leaf+stem elongation that these treatments had no difference with complete control of weed.