University of Georgia
October 27, 2004
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By Susan Varlamoff
University of
Georgia
By measuring the nighttime
respiration rate of plants, University of Georgia
scientists hope to develop a way farmers can detect
environmental stresses in their fields.
Stresses like low soil
moisture, high or low air temperatures, weeds, insects
and diseases can reduce plants' growth, yields and
quality. They can hurt a plant before it shows any signs
of problems.
During the recent drought,
the lack of rain greatly damaged plants. Finding a way
to know when soil moisture levels become low before the
damage occurs is an important reason for this research.
Looking for
a connection
"We're essentially looking
for a correlation between environmental stress and high
nighttime carbon dioxide respiration rates," said
Anandakumar Karipot, an assistant research scientist
with the UGA College of Agricultural and Environmental
Sciences.
Karipot, professor Monique
Leclerc and postdoctoral associate Gengsheng Zhang are
analyzing the data for this project in the UGA
Laboratory for Environmental Physics in Griffin, Ga.
CAES agronomist John Beasley and U.S. Department of
Agriculture physiologist Diane Rowland are also members
of the research team.
Environmental stresses
typically reduce the transpiration rate and the amount
of water vapor given off by plants. Lower transpiration
rates increase plant temperatures. They also increase
nighttime respiration rates that produce carbon dioxide. |
 |
|
University of Georgia scientists are using this Eddy
covariance system to measure the nighttime respiration
rate of plants. The scientists hope to develop a way
farmers can detect environmental stresses in their
fields. The Eddy covariance system include a fast-
response, sonic gauge that measures wind speed in three
directions and an infrared gas analyzer that determines
carbon dioxide concentration fluctuations. |
Reduced growth,
yield and quality
When the plant expends energy to
respire faster, it can't produce as much food for itself
(photosynthesis). This reduces its growth, yield and quality.
"It's similar to a human being: if
you can't prespire, your body overheats and your respiration
rate increases," Beasley said. "When a peanut plant is stressed,
it can't produce the pod or fruit."
The scientists are measuring carbon
dioxide fluxes above a peanut field at the UGA Southwest Georgia
Research and Education Center in Plains, Ga.
The sensors, known as an Eddy
covariance system, include a fast- response, sonic gauge that
measures the wind speed in three directions and an infrared gas
analyzer that determines carbon dioxide concentration
fluctuations.
Together, these sensors provide
information on plants' uptake of carbon dioxide emissions.
They also record supporting
measurements of soil temperature, soil water content and solar
and earth radiation. The scientists collect data from planting
until harvest. That helps them study variations in carbon
dioxide fluxes and their relation to water stress at different
stages of plant growth.
Uniform fields work
best
There is no photosynthesis at night.
That's when plants respire and release carbon dioxide. So the
variations in nighttime carbon dioxide levels will indicate
environmental stress.
"It's important that the peanut field
we chose for this study is fairly large, flat and uniform with
similar soil properties," Karipot said. "This ensures that
similar conditions exist throughout the field and the carbon
dioxide variations are representative of the peanut crop."
A weather-monitoring station also
measures wind speed and direction, rainfall, air temperature and
humidity and solar radiation in the field. This information will
help the scientists understand the microclimatic influence on
the plants' growth and yield. It will help them better interpret
the carbon dioxide respiration data.
"We would like to extend our research
next year to two fields," Karipot said, "one with irrigation and
one without irrigation, and see the difference in respiration
rates of the crops with and without water stress."
This research could be developed into
a tool to warn farmers of water stress in their fields and help
them manage irrigation better. |
