Wine Sees the Light
Growing grapes on trellis systems yields
more fruit, heightens flavour
Vanden Heuvel has found that growing grapes on trellis systems
maximizes light to the fruit, which yields more grapes and
heightens their flavour.
PHOTO BY MARTIN SCHWALBE
When it comes to growing grapes for winemaking,
researchers say let there be light.
Justine Vanden Heuvel, a PhD student in the Department
of Plant Agriculture, has found that growing grapes on trellis
systems maximizes light to the fruit, yielding more grapes
and heightening their flavour.
She's worked with more than 2,000 vines, alongside advisers
Helen Fisher of the Vineland Research Station and Prof.
Alan Sullivan, to achieve the ultimate trellising system.
"I hope my research will give grape growers in all
cool-climate areas a better understanding of how to grow
grapes that will make high-quality wine," Vanden Heuvel
Historically, it was thought that a higher yield of grapes
meant lower-quality fruit. But in the 1980s, a New Zealand
researcher reported that the amount of fruit on a vine was
not actually an indicator of quality. Since then, emphasis
has turned to controlling the vigour of a vine, which is
the size of the vine and its productivity. Trellising is
one way of doing so; it involves manipulating the architecture
of the vine to control vigour and increase the light exposure
to the grape clusters.
High fruit quality depends on light exposure on clusters
because light allows the fruit to accumulate sugar (sugar
is an important measure of fruit quality because it translates
directly to alcohol level fermentation). Vanden Heuvel has
confirmed that high yield and high fruit quality can exist
at the same time.
Now, she's examining the vigour of the vine and yield and
the quality of the fruit and the wine that comes from it.
She's testing the trellising systems for two cultivars,
the white grape Chardonnay and the premium red wine grape
Vanden Heuvel's comprehensive study includes four traditional-type
trellis systems and two of their modern counterparts. She
is examining the density of the vine using a light sensor
to measure the penetration of light into the internal vines
of the plant. The research includes testing the effectiveness
of alternative contemporary trellis systems.
She has discovered that modern trellis systems increase
grape quality because they allow more light penetration
to the vines.
Traditional trellising zones tend to concentrate the fruiting
zone - where the fruit grows on the shoots, says Vanden
Heuvel. Her research compares the traditional trellising
systems with the newer systems in the Niagara Peninsula.
"I'll be able to tell grape growers why certain trellising
designs function better for both productivity and wine quality,"
Vanden Heuvel was invited to present her current findings
to the American Wine Society in South Carolina in November.
This research is sponsored by the Ontario Grape and Wine
Adjustment Program, the Ontario Ministry of Agriculture,
Food and Rural Affairs, the American Wine Society Educational
Foundation and the eastern section of the American Society
of Enology and Viticulture.