Page 55 - Grapevine July-Aug 2020

Around The Vineyard

and the ripening berries.

If grapes are grown in a desert, of course, we need
to irrigate. This gives us a chance to manipulate vine
water stress at our will, in the absence of rainfall.
The rest of this article discusses how to manage the Professional Certificates
desired level of water stress.
Delivered via Distance Education
Irrigated Vineyards Viticulture • Winemaking

Irrigation research was one of my first projects “Program combines
when I started a viticulture career in the mid-1960s the theoretical with the
in Australia. Then, drip irrigation was very new, and practical aspects - real
I published one of the first studies on the method world solutions. I can’t
recommend it strongly
with wine grapes, comparing drip to flood irrigation. enough for either a fu-
ture or current grower.”
This was also a time of new technology for mea-
suring plant and soil moisture. Gypsum block and James Kasparek
Class of 2018
tensiometers were common then, and soon soil
capacitance meters were to be introduced to mea-
sure soil moisture. 806‐834‐1627

Evaluating the Pressure Bomb grapesandwine.ttu.edu

In the late 1960s, pressure bombs used to mea-
sure leaf and stem water potential were introduced.
The pressure bomb was a powerful tool to directly
measure plant water stress, and help understand
how grapevines respond to soil moisture conditions
and the daily pattern of weather conditions.

After sunset, grapevines recover gradually from
the water stress of the day before. Then, at sunrise,
the plants begin to experience mild water stress. As
air temperature increases, and as humidity decreas-
es, so water stress experienced by the plant increas-
es, being at a maximum in early afternoon. As
sunlight levels decrease towards late afternoon, the
water stress experienced by the grapevine recovers
somewhat, again declining substantially after sun-
set.

Our published studies determined a major impact
of current weather conditions on grapevine water
stress. Grapevines experience the most water stress
with bright sunlight, high temperatures, low humid-
ity and high wind speed. These are all conditions
that cause the most rapid water loss from the vines.

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