Use of Crop Plants for Removal of Toxic Metals.

Abstract

Phytoextraction is an environmentally sound and cost-effective technology for cleaning up soils contaminated with toxic metals. The success of phytoextrac tion depends on the ability of plants to produce large amounts of biomass. In addi tion, plants must be tolerant to the target metals and be efficient to translocate metals from roots to the aboveground organs. The effectiveness of phytoextraction also depends upon site and metal species. However, the amount of metals extracted by plants is basically decided by (1) the metal concentration in dry plant tissues and (2) the total biomass of the plant. Certain varieties of high-biomass crops have been found to have the ability to clean up the contaminated soils. The major advantage of using crop plants for phytoextraction is the known growth requirements and well established cultural practices. One of the most promising, and perhaps widely studied crop plant for the extraction of heavy metals is Indian mustard. Other crops like sweet sorghum, oat, barley, maize, and sunflower are also reported to accumulate toxic metals. As established cultural practices may not elicit the same plant response as observed under non-contaminated conditions, attention must be paid on develop ing suitable agronomic practices to optimize the growth of plants even under con taminated conditions. Further, a coordinated effort is required to collect and preserve germplasm of accumulator species where molecular engineering can play a key role in developing engineered plants capable of cleaning up contaminated soils and commercializing phytoextraction strategies