VETIVER GRASS, VETIVERIA ZIZANIOIDES: A CHOICE PLANT FOR PHYTOREMEDIATION OF HEAVY METALS AND ORGANIC WASTES

Glasshouse and field studies showed that Vetiver grass can produce high biomass (> 100t/tha(-1)year(-1)) and highly tolerate extreme climatic variation such as prolonged drought, flood, submergence and temperatures (-15 degrees-55 degrees C), soils high in acidity and alkalinity (pH 3.3-9.5), high levels of Al (85% saturation percentage), Mn(578 mg kg(-1)), soil salinity (ECse 47.5 dS m(-1)), sodicity (ESP 48%), and a wide range of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn). Vetiver can accumulate heavy metals, particularly lead (shoot 0.4% and root 1%) and zinc (shoot and root 1%). The majority of heavy metals are accumulated in roots thus suitable for phytostabilization, and for phytoextraction with addition of chelating agents. Vetiver can also absorb and promote biodegradation of organic wastes (2,4,6-trinitroluene, phenol, ethidium bromide, benzo[a]pyrene, atrazine). Although Vetiver is not as effective as some other species in heavy metal accumulation, very few plants in the literature have a wide range of tolerance to extremely adverse conditions of climate and growing medium (soil, sand, and tailings) combined into one plant as vetiver. All these special characteristics make vetiver a choice plant for phytoremediation of heavy metals and organic wastes.