HEAVY METALS EFFETS ON PLANT GROWTH AND METABOLISM: A REVIEW

Environmental pollution by metals became extensive as mining and industrial activities increased in the late 19th and early 20th century. The current worldwide mine production of Cu, Cd, Pb and Hg is considerable. These pollutants, ultimately derived from a growing number of diverse anthropogenic sources (industrial effluents and wastes, urban runoff, sewage treatment plants, boating activities, agricultural fungicide runoff, domestic garbage dumps, and mining operations) have progressively affected more and more different ecosystems. Generally phytotoxic effects of Cu, Cd and Hg are studied well in agricultural crops but such study in medicinal plant is rare. As plants are exposed to more than one heavy metal and interaction between metals is common phenomenon thus it was of interest to study the interactive effects of Cu, Cd an Hg on growth and biochemical changes in medicinal plants. The selection of medicinal plants is based on the fact that now a days the ill effects and side effects of herbal drugs are reported in the users of herbal drugs. One of the reasons of such effects is due to the occurrence of various toxic metals in herbal drugs.