Effect of cadmium (Cd) on the primary metabolic activities and elemental distribution in roots was explored in Acanthus ilicifolius L., a halophyte with phytostabilization potential. The rate of photosynthesis decreased in the CdCl2 treated plants and this reduction was mainly attributed to the reduction of leaf area, photosynthetic pigments, impaired gaseous exchange caused by the stomatal closure and tissue water status. However, respiration rate was significantly higher in the CdCl2 treated plants which aid the plant with additional energy required for the metabolic activities. Distribution of essential elements in the roots exhibited significant differences from that of control, which indicate the nutritional adaptation developed by A. ilicifolius under the influence of toxic metal ions. Thus, Cd toxicity is neutralized through the resource allocation from the growth process to processes that increase the fitness of the plant to encounter adverse environmental condition. In addition, the absorbed Cd is retained in the cortical cells of root thereby preventing the upward movement to shoot thereby making the plant a potential candidate for phytostabilization of Cd.
Keywords: cadmium; chlorophyll; osmotic potential; photosynthesis; phytostabilization.