evaluation of crops sensitivity to total (mesosulforun+metsulforun) herbicide soil residue

abstract in order to study the sensitivity of seven crops to total herbicide soil residue, an experiment was carried out under controlled conditions in 2009 at the college of agriculture, ferdowsi university of mashhad-iran. in this study 7 crops (pea, bean, lentil, corn, rape, beet and tomato), across 7 simulated soil residual concentration of total herbicide (0, 0.0002, 0.0005, 0.001, 0.002, 0.004 and 0.006 mg kg-1 soil) were evaluated in a completely randomized design with factorial arrangement and three replications. soil samples were wereprepared and transported to 10 cm diameter pots and crop seeds were planted. crops emergence percentage was determined 1 week after emergence. survival, shoot and root biomass production was measured 30 days after emergence. plants response to total residue was fitted with sigmoidal 3 and 4 parametric equation to the shoot biomass data as a function of the herbicide residue concentrations and was used to calculate the residue concentration for 50% inhibition of plants shoot growth inhibition (id50). results showed, that the effect of different total residue concentration were significant (p<0.01) on all plant characteristics. as total residue concentration were increased, emergence, survival, shoot and root biomass production were decreased on all crops. based on the results pea and rape had the lowest (29.3, 30 %) and highest (93. 5, 86/3 %) shoot and root dry matter lost respectively. based on shoot ed50 parameter, corn (0.0031 mg kg-1 soil) was the most tolerant and tomato(0.0001mg kg-1 soil) was the most susceptible crops to total soil residue. the other crops tolerance to total residue ranked as follow: rape < sugar beet < bean