the effects of two control methods of cut and shade on aquatic weeds rowth of coontail and watermilfoil under laboratory condition

abstract coontail (ceratophyllum demersum) and watermilfoil (myriophyllum spicatum) are current submersed weeds in many fresh waters of iran. the excessive growth of these plants causes the reduction in utilization of water resources and making some ecological and economical damages in these areas. the aim of this study was to determine the response of two submerged aquatic weeds of coontail and watermilfoil to light reduction, cutting (without, once and twice) and their incorporation under laboratory (aquarium) condition. the experiment was conducted in factorial design, with three replications. the experimental traits included the length and dry weight of plants. the experimental results showed that, cutting and shading caused a significant effect (p≤0.01) on length and dry weight of test plants. also, twice cutting compared with once, due to more reduction in plants carbohydrate storage resulted in better control of both species.