Page 51 - Grapevine NovDec 2021

Around The Vineyard

In his research, Castellarin found that applying a
water deficit in vineyards increased the concen-tra-
tion of pigments and tannins, not only by reducing
the size of the berry but also by stimulating the
biosynthesis of these compounds. He also observed
that several aromas were affected along with the
color of the wine. In addition, wines produced from
vines exposed to this water deficit had a darker
or higher intensity of color and aromas associated
with red fruit.

The effect of drought or water deficit application
on white grapes is less noticeable. Water deficits in
the vineyard are not often applied to white grape
varieties. In a 2012 study on white grapes grown
under severe stress, researchers observed that the
fruit harvested from those stressed grapevines had
a higher concentration of terpenes.

Researchers also observed that the trapped water
stimulated the metabolic pathways that synthesize
terpenes. That means that it did not only affect
berry size but significantly affected the biosynthesis
of specific metabolic pathways that work during
berry ripening. The study showed that what they
saw on the grapes directly affected the wine, and
that by applying a water deficit, they could increase
the concentration of these aromas.

A three-year study was conducted in the
Okanagan Valley in British Columbia, a significant
Canadian wine region and an area called the infa-
my desert “Nk’Mip” by Canada’s First Nations. This
semi-arid shrubland has very low precipitation,
with only 100 to 130 millimeters of rain during the
growing season. In this study, researchers sought
to develop strategies that limit irrigation by apply-
ing moderate stress levels to the grapevines to
improve aromas and save water.

They wanted to assess how providing suboptimal
irrigation amounts could affect yield and the com-
position of the fruit at harvest. The study focused
on regulated deficit irrigation, managing irrigation
so the plant receives regulated stress. They decid-
ed on moderate stress conditions that they knew
would not strongly affect the plant’s growth but
that they hoped could strongly affect the quality of
the grapes.

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