BIOACCUMULATION AND PHYSIOLOGICAL-EFFECTS OF EXCESS LEAD IN A ROADSIDE PIONEER SPECIES SONCHUS-OLERACEUS L

Seedlings of Sonchus oleraceus L. were transplanted to soil supplied w ith lead acetate at dosages of 0, 800, 1600 and 3200 mg kg(-1) DW. Mea sures of chlorophyll content, peroxidase (POD) activity, shoot length, biomass and Pb content in the plant tissues were obtained from the ex perimental plants. With increasing amounts of Pb in the soil, the chlo rophyll content, shoot length and biomass decreased, while POD activit y and Pb content in the plant tissues increased. At 3200 mg kg(-1) Pb treatment, Pb content in the plant leaf, stem and root were 65.67, 149 .82 and 1113.24 mg kg(-1), respectively. Only at 3200 mg kg(-1) Pb tre atment did chlorophyll content, shoot length and biomass significantly increase by 18, 15 and 44%, respectively, while POD decreased by 39% over the control. The potential of applying this species in phytoremed iation of Pb contaminated roadside soils and thus restoration of the r oadside vegetation are discussed. (C) 1997 Elsevier Science Ltd.