Accumulation and Phytotoxicity of Lead in Cynara scolymus

Effects of different lead concentration (0, 100, 200, 400, 600, 800, 1000 and 1500 μM) on growth, pigment concentration, biochemical parameters and lead accumulation in Cynara scolymus L. (artichoke) were investigated. The experiment was conducted hydroponically in a lead spiked solution. The lead toxicity exhibited a decline in growth and chlorophyll content of artichoke at elevated concentrations (>100 μM). In contrast, proline and total soluble sugar increased significantly as lead concentration augmented. The accumulation of lead was found to increase in a concentration dependent manner with a maximum of 411 mg kg^-1 at 1500 μM. Root accumulated more lead than shoot. The loss of chlorophyll content was associated with disturbances in photosynthetic capacity which ultimately results in the reduction of artichoke growth. Increase proline and total soluble sugar content suggest that compatible solutes may contribute to osmotic adjustment at the cellular level and enzyme protection stabilizing the structure of macromolecules and organelles. The higher lead uptake and ischolar_main to shoot translocation efficiencies than none accumulating plants was indicative of its greater lead accumulating capacity. Collectively, our results indicate that artichoke has physiological traits associated with accumulation of lead to relative high levels and it can be useful for restoring lead-contaminated sites.