New Thermal Remote Sensing System Scans
Crops By Jim
July 2, 2002
Changes in a crop canopy's temperature may give scientists the
most complete picture of how much water stress the plants are experiencing
during drought, according to Agricultural
Research Service scientists.
Previously, researchers have gauged drought stress using sensors
to measure the water pressure of individual leaves removed from the plant, or
the sap flow through the plant stem. They've also monitored soil moisture to
determine crop water use and to schedule irrigation. While these methods are
reasonably reliable, they are time consuming and costly.
Now scientists at the
Application and Production Technology Research Unit in Stoneville, Miss.,
report that changes in canopy temperature may be a more reliable indicator of
water stress because canopy temperature rises as water stress increases.
Evaluating the entire plant canopy gives a more complete picture
of a crops health than one gets from measuring a single leaf from the top
of a plant, according to Plant Physiologist Gretchen Sassenrath-Cole. She and
her colleagues are collaborating with H. C. Lyle Pringle, a
Mississippi State University scientist
located at the Delta Research and
Extension Center in Stoneville.
They developed an unobtrusive tracking system that uses thermal
sensors to remotely monitor canopy water stress and temperature. The system can
be rapidly deployed and positioned at various levels, measuring individual
leaves or entire canopy elements.
Sensors are located at the end of a boom attached to a rotating
yoke. The entire pivoting system is connected to a tower mounted on the front
rack of an all-terrain vehicle. The boom, engineered by Sassenrath-Cole and
technician Ray Adams, is raised or lowered over the canopy by a hydraulic
cylinder to focus the sensors on a specific area. Data and images from a video
camera are simultaneously downloaded to an on-board computer.
Read more about this research in the
July issue of
Agricultural Research magazine.
ARS is the U.S. Department of
Agricultures chief scientific research agency.