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A pioneering study into the geometry of root mass systems of grape
vines has been undertaken by research staff from the Center for
Irrigation Technology (CIT) and the Viticulture and Enology Research
Center (VERC).
Key objectives of the project are to determine changes in the root mass
of grape vines now irrigated by surface and subsurface drip systems
rather than conventional flood irrigation.
The drip lines have been in place three years, so the vines have had a
chance to adapt to the new irrigation treatments, reported Morton Rothberg, CIT consultant who is working on the project.
"
Our objectives are to find out the distribution of roots under different
irrigation systems. We want to see if there is a different rooting pattern
under the different systems," he said.
To begin the project last fall, CIT technicians dug 24 pits in a
Thompson Seedless vineyard west of Fresno, California. The pits were
dug two meters deep, four meters long, and one meter wide -
perpendicular to the vine rows.
Once the pits were dug, technician teams set up grids on the side of the
wall facing the nearest vine stalk. The wall was washed with water to
expose the roots, then the exposed root ends were counted and
recorded.
The study focused on four treatments of drip irrigation and one control
treatment of conventional flood irrigation. Two of the drip systems were
above ground and two were subsurface.
"
What we found initially was that around the buried drip we did get a
tremendous amount of root growth," Rothberg said. If that response
proves to be consistent throughout the treatments, it would allow new
and important questions to be asked regarding irrigation and production
methods. For example, could less water and fertilizer be applied to the
vineyard and still be sufficient for each plant? Would a more compacted
root system affect plant stability, vigor and yield?
Some of those questions may be partially answered, but the key
objectives of this study were to determine root geometry, which will
include not only numbers and sizes of roots, but distribution curves and
ratios. This is data that scientists, and ultimately growers, will be able
to use to make decisions about the use of surface and subsurface drip
systems.
"
This is a fairly pioneering experiment," Rothberg said. "It is the first
time anything like this has been done, and with the data we may be able
to make some inferences."
Another part of the experiment was to determine the extent of root
intrusion into the emitters. That information, along with mounds of root
data, will have to be statistically analyzed over the next several months,
Rothberg said, with formal publication of the results slated for this
summer.
For more information on the root study, contact CIT at (209) 278-2066.
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