Pb-phytoextraction by jack beans in a Pb-EDTA-treated oxisol

摘要

This research work aimed at evaluating the phytoextraction potential of jack beans (Canavalia ensiformis L.), under greenhouse conditions, using samples of an Oxisol treated with Pb and EDTA. Treatments consisted of six Pb rates (0; 100; 200; 350; 1,200; and 2,400g·kg<'-1> soil) applied as Pb<,3> (NO) <,2>, without and with EDTA (0 and 0.5g·kg<'-1>) in a completely randomized design arranged in a 6×2 factorial with three replications. Plants were grown in 3 L-pots up to 45 days of age. The variables determined were: available Pb and ionic Pb species in the soil solution, and plant shoot Pb concentration and accumulation. Soil Pb-availability was quantified in soil extracts obtained with DTPA Ionic speciation was assessed using the software Visual-Minteq 2.30. Jack beans were considered potentially good Pb- phytoextractors due to their high Pb concentrations (up to 800mg·kg <'-1>) and dry matter yields. EDTA applied to the studied Oxisol resulted in higher Pb and Fe concentrations in the soil solution, and increased metal accumulation in jack bean plants. EDTA application reduced free Pb<'2+> and increased the chelated forms of Pb (PbEDTA<'2>) and Fe (FeEDTA<'2>) in the soil solution.