عنوان مقاله [English]
In order to evaluate the soil residue of imazthapyr an experiment based on completely randomized design was carried out at greenhouse of Agricultural Faculty of GonbadKavous University. At this experiment different doses of imazthapyr (0, 4.5, 23, 45, 68, 91, 140, 180, 230, 340 and 450 μg.kg-1 soil) were applied on maize andcotton and finally the dry weight of root and shoot, shoot height, root length and leaf area of crops were measured. Three and four Logarithm logistic curves were used for fitting the data. Results indicated that almost all data were followed the three parameter logarithm logistic curve. Results of separate fitting of the data showed that always the residue of imazthapyr caused reduction of dry weight of the evaluated crops. For 50 percent reduction of shoot dry weight of cotton and maize 13.26 and 21.91 g.a.i.ha-1of imazthapyr were needed respectively. For 50 percent reduction of root dry weight of cotton and maize 72.75 and 25.19 g.a.i. ha-1of imazyhapyr were needed. Generally the results of data simultaneously fitting showed that maize root and shoot sensitivity to imazthapyr were always more than cotton and shoot. Shoot height, root length and leaf area were decreased as imazthapyr residue was increased.