Changes in photosynthetic pigments and phenolic and flavonoid compounds of Lemna minor under chromium treatment

Heavy metals known as the most toxic pollutants of the environment, resulting from different activities such as industrial, agricultural and mining which released to surface and ground waters. Physico-chemical methods are not cost-effective because of their high cost and energy, so bio-refinery systems can be replaced. Phytoremediation is an affordable, efficient and simple process that can replace with traditional methods. In several studies the ability of Lemna species in absorbtion of heavy metals have been investigated. In this research, the effect of heavy metal (Cr) pollution and potential of Lemna minor was examined. This aquatic macrophyte was exposed to different concentrations of Cr (0-100 mg/L) in Hoagland diluted media for 7 days. Chlorosis and detachment of leaves occurred 3 days after treatments. Rate of the chlorosis and detachment of the leaves was about 10%  in low concentration of the heavy metal and 80% in high concentration of that treatment. Chlorophyll content, total phenolic and flavonoids compounds of the Lemna were assayed after treatments and showed that at 50 to 100 mg/L concentrations, effect of damage were appeared.