THE EFFECTS OF ORGANIC AMENDMENTS ON CADMIUM UPTAKE OF SPINACH (SPINACIA OLERACEA L.) AND PLANT GROWTH UNDER CADMIUM TOXICITY

It has been well-documented that organic amendments reduce heavy metal uptake by plants thereby diminishing their movement in soil. The aim of the present pot experiment is to investigate the potential effects of organic amendments sewage sludge (SS), sheep manure (SM), cattle manure (CM), peat, and humic acid (HA)) on plant growth, cadmium uptake and antioxidative enzyme activity in spinach (Spinacia oleracea L.). The pot experiment was 100 mg kg(-1) cadmium applied to soils with the sequence of: 0%, 10% and 20% levels of SS, SM, CM, Peat and HA with two different levels of 500 and 1000 mg kg(-1) applied. Organic amendment applications, including 10% and 20% Cd + SS and 20% Cd +CM and 20% Cd+ SM significantly decreased cadmium uptake, respectively, 80.19%, 77.70%, 78.76%, and 73.12% compared to cadmium application alone. Cadmium application alone caused higher activity in ascorbate peroxidase (APX) activity and malondial-dehyde (MDA) content than control. Organic amendments resulted in decreased APX activity and MDA content. All organic amendment applications significantly decreased cadmium uptake in spinach. However, SS was more effective than others applications, due to the low amount of heavy metal in SS. Additionally, another account for its effectiveness may be that the other organic matter level of the SS is higher than the other organic amendments.