Accumulating effects of sunflower (Helianthus annuus L.) on copper in soil

Pot experiments cultivating sunflower in different artificially copper-contaminated soil in greenhouse were conducted. The results show that the biological properties of sunflower such as dry weight of shoot, dry weight of root, leaf area are reduced with the increase of copper concentration added to soil. The root growth is seriously inhabited under 200mg/kg Cu treatment. But the maximal plant height is gotten under the 100mg/kg Cu treatment. It is also found that the accumulating ability of copper of sunflower changes with the copper concentration. The root of sunflower accumulates more copper when the Cu concentration in soil is lower, while the Cu contents in shoot are very low. Under the treatment of 100mg/kg Cu in soil, the Cu content in the leaves is higher than that in the root, reaching 857±297mg/kg (dry weight), and the ratio of Cu accumulation in leaf to that in root reaches 1.27. So the sunflower can extract more copper by the harvesting because there is a higher accumulation of Cu in the sunflower shoots and leaves when Cu concentration in the soil is higher, but the growth of sunflower is restrained. So when sunflower is used to remediate copper-contaminated soil, other means such as inoculation of rhizospheric microorganisms, transgenic, agro-biological environmental engineering technique, and so on should be considered to increase its biomass.