Effects of cadmium and chicken manure on dry weight and some heavy metal amounts for healthy lettuce (Lactuca sativa l.) consumption

Abstract

Although the plants might be grown without showing any toxicity symptoms in the soils having cadmium (Cd) concentrations within the permissible ranges, it may give harm to human health depending to its' metal concentrations and also to the consuming amounts. Regarding to analyse such problem, a greenhouse experiment was conducted to evaluate the effects of cadmium and chicken manure on the dry weight amounts of lettuce (Lactuca saliva L.) leaves and roots and on some heavy metal concentrations, under Cd containing soil conditions. Increasing doses of Cd (0, 10, and 20 mg kg(-1) Cd) and increasing doses of chicken manure (0, 500, 1000, and 2000 kg da(-1)) were applied to soil. Although the applied Cd concentrations were within the maximum limits mentioned in various countries, increased the Cd concentrations both in the roots (68.50 mg kg(-1)) and in the leaves (39.52 mg kg(-1)) and found over the limits of WHO. It was observed that not only Cd but also Pb, Cr, Zn, Fe, Mn and Cu were accumulated in lettuce roots rather than leaves without giving any chlorotic toxicity symptoms. However, decreased the dry weight amounts of lettuce both in leaves and in roots and also the amounts of other elements. The least leaf (6.43 g pot(-1)) and root (2.54 g pot(-1)) dry weight yield was obtained from the highest dose of cadmium (Cd2). Adding chicken manure to the soil under Cd improved the dry weight of the plants, and lessen the amounts of Cr, Pb, and the other micro nutrients but not found proficient to decrease Cd amounts. Because of health-related risks, there is a need to control and rearrangement for the limits of Cd in soils and in plants consumed by humans.