The decontamination of soils and substrates contaminated with arsenic through phytoremediation techniques has attracted increasing interest of researchers and specialists of environmental sciences. This study aimed to evaluate the potential of the species townsville stylo (Stylosanthes humilis HBK), forage peanut (Arachis pintoi Krapov. & Gregory), oat (Avena strigosa Schreb), and ryegrass (Lolium multiflorum Lam.) for phytoremediation of arsenic-contaminated soils. Samples of a Red Yellowh Latossol (Oxisol) were incubated with different doses of arsenic (0; 50; 100 and 200 mg dm-3). After this incubation period, the four species were sown and, after germination, soil samples were fertilized accordingly. Sixty five days after sowing, plants were evaluated for height and biomass weight of roots and shoots. Arsenic content in young, intermediate, and old leaves, stem and roots and the As-translocation index (IT) were determined. By regression analysis we estimated the critical contents for available arsenic (TC) in soil which reduced the biomass production by 50 %. The species differed in As-tolerance; no morphologic symptoms of As toxicity were observed for ryegrass, forage peanut and townsville stylo. The TC values for oat and ryegrass were high. In forage peanut and townsville stylo plants the absorption and shoot translocation of arsenic were higher, but the potential of forage peanut for phytoremediation programs is greater. Ryegrass, peanut and stylo plants can be used in phytostabilization and / or the revegetation of As-contaminated areas. When forage species are used with phytoremediation purposes, special care is needed, such as the isolation of the area, to avoid the entry of the element into the food chain.
arsenate; Stylosanthes humilis; Arachis pintoi; Avena sativa; Lolium multiflorum
