Page 53 - Grapevine NovDec 2021

Around The Vineyard

The study concentrated on Gewürztraminer, a tent across the seasons.
variety known for its aroma. The study started
with a control treatment: standard commercial While early and prolonged deficit treatments
irrigation, which would not put the plant under reduced yield, applying deficits later on during
stress. They applied stress 30 days from blooming the ripening process did not affect the number of
to harvest for a moderate level
of prolonged water stress. They
analyzed brief gas exchanges,
photosynthesis, all the physi-
ological parameters related to
the grapevine and physiology,
and then the compositional
parameters of the fruit like sug-
ars, acids and free and bound
terpenes.

According to Castellarin, they
managed irrigation by weekly
measuring leaf water potential
and then applying irrigation
volumes accordingly. “The
irrigation volume change obviously depending on grapes grown or harvested. When they measured
treatment. With the early deficit (a deficit applied the grapes for composition, total soluble solids and
from 30 days after blooming to veraison), we could acidity, researchers found that the irrigation treat-
save 30% of the irrigation water. With late deficit (a ment with the most significant effect was the pro-
deficit applied from veraison to harvest), we saved longed deficit, which reduced sugars and increased
38% of the irrigation water. With prolonged deficit the acidity.
(a deficit applied from 30 days after blooming to
harvest), we saved 50% of the irrigation water,” he Across three seasons, the late deficit treatment
said. consistently improved the concentration of some
of the free terpenes, particularly Geraniol, which
When they applied some level of stress, one is the primary terpene synthesized in Gewürz-
of the first responses was a reduction in leaf gas traminer grapes. They did not observe an increase
exchanges. Moderate stress levels reduced photo- in the bound terpenes. Researchers learned that if
synthesis by 50%, a finding that was pretty consis- they applied a moderate water deficit during rip-

877-892-5332 The Grapevine • November - December 2021 Page 51

Grapevine Main Pages GV111221_Layout 1-1 .indd 51 10/26/21 3:43 PM