Columbus, Ohio
August 30, 2007
Little can be done to prevent
soybean injury due to flooding, but the future is bright for
farmers to grow varieties tolerant to the effects of standing
water.
Ohio State University
researchers, collaborating with the University of Missouri-Delta
Center, are studying the effects of flooding on soybean lines in
the hopes of identifying tolerance genes that can be bred into
existing susceptible varieties. After one year of research,
results look promising.
“Things so far look good,” said Tara VanToai, an Ohio State
University plant scientist with the U.S. Department of
Agriculture-Agricultural Research Service. “We can tell just by
looking at the soybean lines which ones are exhibiting flood
tolerance.”
VanToai and her colleagues are analyzing 220 soybean lines that
carry the genes of a tolerant Asian variety and a flood-prone
variety. The lines, grown in Missouri and at the Ohio
Agricultural Research and Development Center in Wooster, Ohio,
are being evaluated for yield, plant height, leaf greenness, and
level of survival after fields are flooded.
“We flood the fields until the plants start to show symptoms.
Then we quantify the tolerance of each line under those field
conditions,” said VanToai. “Our hope is that when we compare the
data between Wooster and Missouri, we find lines grown in both
locations that are flood tolerant.”
The research, partly funded by USDA-ARS, stemmed from earlier
work conducted by VanToai that found that carbon dioxide buildup
in flooded fields is a major cause of injury and death to
soybean plants.
“It was previously suspected that lack of oxygen was the main
problem with damaged or dying soybeans associated with flooding.
But what we found was that, although lack of oxygen played a
small part, carbon dioxide build-up was the biggest factor,”
said VanToai. “Carbon dioxide is toxic to plants, causing them
to turn yellow, become stunted and drop leaves, resulting in
yield reductions, and, in some cases, death.”
Researchers discovered that soybean plants adapt to low or no
oxygen by producing additional roots and modifying the stem to
help transport oxygen from the shoot to the roots. Soybeans,
however, are susceptible to carbon dioxide. The carbon dioxide
concentration of non-flooded soybean fields is about 1 percent,
but increases to 30 to 35 percent after two weeks of flooding.
Soybeans growing under that situation face yield reductions as
high as 60 percent.
“Based on these findings, we were very interested in improving
the tolerance of soybeans to flooding, from the standpoint of
saying, ‘Well, if beans lose 60 percent of their yields after
seven days of flooding, then varieties we develop that lose only
20 percent of their yields would help farmers.’”
Identifying varieties tolerant to carbon dioxide levels in
flooded fields or prolonged standing water is only a piece of
soybean research puzzle. Researchers also recognize the
importance of identifying varieties that exhibit resistance to
diseases associated with flooded soil, such as Phytophthora root
rot.
OARDC plant pathologist Anne Dorrance is collaborating with
VanToai to identify the genes of flood-tolerance and
Phytophthora resistance that can be used to develop future
varieties.
“The cross research is very exciting because it is helping us
better understand the relationship between flooding and
diseases, and what it takes to keep soybean plants alive and
grow in flooded soil,” said VanToai.
Other researchers collaborating on the project include Rouf
Mian, an OARDC researcher with USDA-ARS, and Grover Shannon and
Henry Nguyen of the University of Missouri.
The soybean is Ohio’s No. 1 field crop commodity, generating
over $1 billion to the agricultural industry, according to the
Ohio Department of Agriculture. Soybeans are grown in Ohio for a
wide variety of uses -- from grain to food to renewable energy
production. |
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