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
