Abstract
ABSTRACT The effects of cadmium (Cd2+) on growth status, chlorophyll (Chl) content, photochemical efficiency, and photosynthetic intensity were studied on Canna indica Linn. Plant specimens that were produced from a constructed wetland and precultivated hydroponically in 20 L of 1/10 Hoagland solution under greenhouse conditions for 1 week were exposed to cadmium in concentrations of 0, 0.4, 0.8, 1.6 and 3.2 mg L―1 Cd2+, respectively. The results show that leaves were injured in the Cd2+ solution by the third day of exposure and the injury became more serious with an increase in the applied heavy metal. Under 3.2 mg L―1 Cd2+ treatment, growth retardation, the decrease of chlorophyll content from 0.70 to 0.43 mg g―1 FW, and a decrease in Chl a/b ratio from 2.0 to 1.2 were observed. Chl a was more sensitive than Chl b to Cd2+ stress. The decrease was the same with photochemical efficiency. Photosynthetic intensity decreased by 13.3% from 1.5×104 μmol m―2s―1 CO2 in control to 1.3×104 μmol m―2s―1 CO2 in the treatment of 3.2 mg L―1. Because Canna species are used in heavy metal phytoremediation, these results show that C. indica can tolerate 0.4 to 0.8 mg L―1 Cd2+. Therefore, it is a potential species for phytoremediation of cadmium with some limitations only at higher concentrations.
Published Version
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