February 24, 2004, ARS News Service: Because
of their ability to sop up selenium, some plants have
been enlisted in efforts to clean up soils and wastewater
that have an excess of this potentially toxic element.
Now Agricultural Research Service scientists have shown
that the way contaminated irrigation water is delivered
to plants affects how much selenium they will absorb
Soil scientist Donald L. Suarez and plant physiologist
Catherine M. Grieve, working with soil scientist James
A. Poss, found that sprinkling--rather than flooding--kale
and turnip plants with selenium-laden drainage waters
allowed the plants to absorb almost twice as much selenium
from the water. Suarez, Grieve and Poss are at the agency's
George E. Brown Jr. Salinity Laboratory in Riverside,
Boosting plants' uptake of selenium creates a place
to naturally "store" the element, thereby
decreasing the amount of selenium that might otherwise
leach into drainage and groundwater.
As a possible additional benefit, the selenium-enriched
kale and turnip plants--as well as other crops irrigated
by sprinkling--could be used to supplement the diets
of livestock raised in selenium-deficient regions of
the United States. Animals must consume some of this
essential nutrient for optimum growth and stress tolerance.
Suarez expects the sprinkler method to work with other
crops, so the findings are likely to aid growers who
are interested in producing selenium-rich vegetables
for health-conscious consumers.
Sprinkling water onto the crops takes advantage of
plants' ability to absorb droplets of water through
openings in their leaves. Plants can also soak up selenium
from water via their roots. But because plant roots
screen out some elements, leaf uptake can be a more
effective way to capture the selenium.