Response of some crops grown in rotation with wheat to the residues of sulfonylurea herbicides in Khuzestan province

Maize and mungbean rotational responses to sulfonylurea herbicides applied on wheat at the previous year were investigated in two separated experiments at Ahvaz in 2006 and 2007. In the first experiment, 10 treatments of herbicides applied to wheat at the year before planting, and after wheat harvesting, the maize crop was planted. Treatments consisted of Chevaliar (idosulfosulfuron + mesosulfuron) at 0.4L/ha, Apyrus (sulfosulfuron) at 28, 42, 56 and 68 g/ha, megaton (chlorsulfuron) at 20 g/ha, bromicide + topic ("bromoxynil + MCPA"+ clodinafop-propargyl) at 1.5+0.8 L/ha, Total (sulfosulfuron +mesosulfuron) at 45 g/ha, atlantis (idosulfuron + mesosulfuron) at 1.5 L/ha and non-treated control. The second experiment was the same as the first one, but the rotational crop following wheat was mungbean. Grain yield, biological yield and harvest index of rotational crops were analyzed. According to the result, when mungbean and maize were planted in rotation with wheat, residues of megaton and apyrus at 56 and 68 g/ha, had the most negative impacts on their yields. So that yield reduction were 37%, 24% and 21% in mungbean and 36%, 10% and 17% in maize, respectively. Therefore, it is needed to pay more attention to the response of rotational crops following wheat to residues of sulfonylurea herbicides in soil.