The Effects of Chitosan Composites on the Concentrations of Cadmium and Some Nutrients of Lettuce Plant

This study aimed to investigate the efficiency of different chitosan composites on lettuce plant and mobility reduction of cadmium in the soil. For this purpose, a pot factorial experiment was conducted in greenhouse conditions using a completely randomized design.The proposed factors were soil cadmium levels (0, 8, 25 and 75 mg/kg) and types of adsorbent (chitosan, biochar, zeolite, nanomagnetite and composites of chitosan-biochar, chitosan- zeolite,chitosan- magnetite and control). Each adsorbent was applied to the soil at the rate of 0.5% W/W. The results showed that the shoot height, the shoot and root dry weight and the concentrations of phosphorus, potassium, iron and zinc in the shoot of lettuce decreased but the cadmium concentration of leaf increased as the concentration of soil total cadmium increased. The results also showed increasing the amount of adsorbents to the soil decreased the toxic effects of cadmium by adsorpting the part of soluble cadmium. As, by application of 0.5% W/W of chitosan-magnetite composite, the concentration of cadmium in the shoot of lettuce decreased about 24.22 mg/kg as compared to the control treatment. But the shoot height and the shoot dry weight increased by 29.57 and 43.6% respectively, and the concentration of phosphorus, potassium, iron and zinc increased by 72.22, 98.78, 267.77 and 128.10% respectively, as compared to the control treatment.