عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In this research chemical forms of lead and zinc in bulk and rhizosphere soil of different cultivars of maize and canola were determined by sequential and single step extraction methods. Some factors affecting chemical transformation of the two elements such as pH, dissolved organic carbon (DOC), their uptake by plant and also cation exchange capacity in the rhizosphere and bulk soil were also assessed. Rhizosphere was obtained with gentle shaking and separating the soil around plant roots. Results showed that zinc uptake was more than lead in both plant cultivars. Zinc and lead accumulation in all cultivars roots were also more than shoots. Translocation index (The ratio of element concentration in shoot to root) in the corn cultivars was higher than canola cultivars (significant correlation= 1%) while the ratio was higher for lead in canola cultivars. Metal concentration in shoots to total metal concentrations in soil (Accumulation factor) showed a similar trend like the translocation index. In total, the corn ability in zinc and lead absorption and extraction in soil was higher compared to canola. There weren’t any significant changes in rhizosphere pH compared to bulk soil. Dissolved organic carbon in the rhizosphere of different cultivars was more than bulk soil and the amount of it in canola was significantly more than corn cultivars. Among each plant cultivars, the absorption rate increased with increasing root exudates. The results of sequential and single step extraction methods showed that the general trend and the soil system tendency (Root-Soil interface) is toward zinc availability in the rhizosphere. The amount of lead in rhizosphere showed no significant changes to bulk soil with none of the extractants in single step extraction method but with regards to the results of sequential extraction method, rhizosphere processes tend to reduce the availability of this element in both plant cultivars.