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Searching for an ozone-tolerant soybean
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[AUG.
9, 2004]
URBANA --
A ring of horizontal pipes 70
feet in diameter seems to hover over a soybean field on the South
Farms at the University of Illinois. The pipes release ozone into
the wind as it blows across the soybean plot, simulating the higher
concentration of ozone that could be a reality for our atmosphere in
the year 2050. "In the Northern Hemisphere, ozone levels in
industrial countries are rising at a rate of 1 to 2 percent a year,
and this trend is predicted to continue," said Randall Nelson, one
of several USDA-ARS and U of I scientists who have been using this
outdoor-air laboratory to study how Illinois crops will fare in the
future.
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Approximately 1 pound of ozone is
released into each ring per day. This amount exposes the growing
soybeans to a level approximately 20 percent higher than the level
found in the air outside of the ring.
A ring of pipes encircles a soybean field on the University of
Illinois South Farms. The pipes release ozone into the air just
above the soybeans, simulating an atmosphere of the future which may
have a 20 percent higher ozone concentration.
The increased ozone levels result in a
significant decrease in soybean yield but not for all soybean
varieties. Nelson said that the most sensitive varieties yielded
over 30 percent less under the elevated ozone concentration than in
normal conditions. The average yield reduction of the 22 varieties
tested was 19 percent. But, a few varieties were quite tolerant of
the elevated ozone, with yield reductions of approximately 5
percent.
"We tested varieties that were grown in
Illinois more than 50 years ago as well as current varieties," said
Nelson. "Ozone-sensitive and ozone-tolerant varieties were found
within both groups. There are genetic differences among our current
varieties for ozone tolerance, but ozone levels are not sufficiently
consistent for soybean breeders to select for ozone tolerance under
natural conditions."
As the group continues to test
varieties, Nelson believes that even more tolerant lines will be
found to exist within the USDA Soybean Germplasm Collection at the
University of Illinois.
"The capacity of the SoyFACE [Soybean
Free Air Concentration Enrichment] facility permits us to currently
evaluate only 22 varieties per year," Nelson said. "We are working
to develop procedures that will allow us to more extensively
evaluate ozone tolerance. It's important to identify those varieties
that are most likely yielding at less than full potential under
current conditions and to identify more highly tolerant germplasm
for developing future varieties."
Ozone exists in two places. Ozone forms
a protective barrier from the sun's ultraviolet rays in the
stratosphere about 15 miles above the earth. In recent years,
the depletion of this ozone has been making news. The decline
increases the ultraviolet radiation that reaches the earth and may
increase the incidence of skin cancer and cause other problems.
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At the same time that the stratosphere
ozone is decreasing, surface ozone is increasing. This ozone
is a secondary pollutant. Nitrogen oxides and volatile hydrocarbons
are products of burning fuels. With the aid of sunlight, these
compounds combine to produce ozone. Because sunlight is critical,
ozone pollution is principally a daytime problem in the
summer. Because ozone is a secondary pollutant, concentrations can
be high in rural areas far removed from the original sources of
pollution.
The problems of surface ozone changes
are regional, depending in part on proximity to urban and industrial
areas. Illinois is likely to be among the soybean-producing areas
with the highest ozone exposure. Concentrations for central Illinois
have exceeded thresholds for soybean yield reduction in recent
years.
The research for this project is funded
by the state of Illinois through the Illinois Council on Food and
Agriculture Research Sentinel Program. The entire SoyFACE project
coordinator is Steve Long, a Robert Emerson Professor in the
Department of Crop Sciences at U of I. Graduate student Kevin Hollis
has been instrumental in the day-to-day data collection and
assessment.
Plant geneticist Randy Nelson (left) observes as graduate student
Kevin Hollis raises the pipes at the SoyFACE facility on the
University of Illinois South Farms.
For more information, visit
http://www.soyface.uiuc.edu/.
Details on SoyFACE and other research
projects will be featured at Agronomy Day 2004, beginning at 7 a.m.
on Aug. 19 at the Crop Sciences Research Education Center, located
south of the University of Illinois' main Urbana campus.
For more
information, including directions and a listing of all of the
research projects to be presented at Agronomy Day 2004, call (217)
333-4256 or visit
www.cropsci.uiuc.edu/agronomyday.
[University
of Illinois news release]
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