1. 9/19/2012
Introduction to Vines and
Wines
Hort/VE 113 Fall 2012
Session 9-Grape Development and
ripening
Grape Structure
A grape cluster is a
complex flower, or
inflorescence, that
consists of a
peduncle, cap stems
(also called pedicels),
a rachis, and berries
that arise from
individual flowers in
the flower cluster.
• Each individual Grape Structure
berry is made up of
skin, flesh (or
pulp), and seeds.
On the outside of
the skin is the
bloom, or waxy y
layer, that helps to
prevent water loss
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2. 9/19/2012
Vine growth stages
• Budbreak (leaf
growth)
• Bloom
• Berry set
• Shatter
• Veraison
• Fruit maturation
• Leaf fall
Budbreak
• vine begins the
process of bud
break in spring
(March)
• first sign of green
in the vineyard
emerges
• form of tiny shoots
Flowering-flower
development
Depending on temperatures, 40-80 days after bud break(May)
flowering begins with small flower clusters appearing on the
tips of the young shoots looking like buttons.
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3. 9/19/2012
Flowering
Fruit set
• follows flowering almost
immediately
• the fertilized flower begins to
develop a seed and grape
berry to protect the seed
• In th North-May, South-
the N th M S th
November
• stage is very critical for wine
production since it determines
the potential crop yield
• Not every flower on the vine Photo credit:Fir0002/Flagstaffotos
gets fertilized; unfertilized
flowers eventually fall off the
vine.
Fruit set
• percentage of fertilized flowers
30 up to 60 or much lower.
• Cli
Climate and vine h l h
d i health
important!
• low humidity, high temperatures
and water stress can severely
reduce the number of flowers
that get fertilized.
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4. 9/19/2012
“Shatter” aka “Coulure”
• caused by a CH2O
deficiency in the Vine
• causes the vine to
conserve resources
that would otherwise
be funneled into the
developing grape
berries.
• Makes berries fall off
• A natural process
Bad weather (cold or hot)
during and right after bloom • Can get out of hand
can make this a problem!
‘Malbec’ sensitive to shattering
If it’s hot-faster shoot growth and more respiration
Uses up available carbohydrates normally devoted to grape development
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Stage 1
•BERRY DEVELOPMENT STARTS
SOON AFTER FERTILIZATION
OF THE FLOWER.
•CHARACTERIZED BY STRONG
GROWTH OF THE SEED AND
BERRY
•AT THIS POINT, THE FINAL
NUMBER OF CELLS IN THE
BERRY IS DETERMINED
•ACIDS ARE ACCUMULATED
•ENVIRONMENTAL IMPACTS
ON BERRY DEVELOPMENT
PROCESSES(SHATTER) OCCUR
HERE
Stage 2
•ALSO KNOWN AS THE ‘LAG’
PHASE
•THE BERRY ITSELF GROWS
SLOWLY
•DURING THIS PERIOD THE
EMBRYO WITHIN THE SEED
MATURES
•THE SEED COAT LIGNIFIES
•TOWARDS THE END OF THIS
STAGE, AS VERAISON
APPROACHES, BERRY CHANGES
COLOR
Veraison
• Grapes are about half their final size when
they enter this stage.
• beginning of the ripening process
• normally takes place around 40-50 days
after fruit set.
– North-late July into August; South-late
January into February
• Within six days of the start of veraison,
berries begin to grow dramatically as they
accumulate glucose and fructose and acids
begin to fall.
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Veraison
• Grapes become their final
colors
– red/black or yellow/green
depending on the grape
varieties.
varieties
• color change due to:
berry skin chlorophyll replaced
by:
– Anthocyanins (red wine grapes)
– Carotenoids (white wine
grapes).
Stage 3-Berry
ripening
•THE PERIOD OF RAPID CELL
EXPANSION AND SUGAR
ACCUMULATION.
•POTASSIUM, AMINO ACIDS
AND PHENOLIC COMPOUNDS
INCREASE
•MALIC ACID IS DEGRADED
•MOST FLAVORS ARE DEVELOPED
Engustment
• During engustment, the berries start to
soften as they build up sugars.
• the cane of the vine starts to ripen as well
changing from green and springing to brown
and h d
d hard.
• The vine begins to divert some of its
energy production into its reserves in
preparation for its next growth cycle.
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Veraison onset
• The onset of veraison does
not occur uniformly among
all berries.
• Typically:
– berries and clusters that are
most exposed to warmth, on
the outer extents of the
canopy, undergo veraison first
– berries and clusters closer to
the trunk and under the
canopy shade undergoing it
last.
http://www.youtube.com/watch?v=nv4ZTKpApyY
Veraison onset
• For the production of high quality
wine, it is ideal to have an earlier
veraison
• The vine is biologically programmed
g y p g
to:
– channel all energies and resources into
the berries
• Houses seedling offspring
• Increases chance of survival
Controlling veraison onset
•Vineyard factors
that can control the
onset of veraison:
–limited water stress
–canopy management
that creates a high
"fruit to leaf" ratio
•can encourage
veraison
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8. 9/19/2012
Controlling veraison onset
• very vigorous vines
– have lots of leaf
shading for
photosynthesis and
water supply
• Can delay the start
of veraison
– vines energies are
directed towards
continued shoot
growth of new buds.
Summary
• The grape berry: independent biochemical
factory that contains: water, sugar, amino
acids, minerals, and micronutrients.
• Synthesis of other components like flavor
and aroma compounds also occurs in the
berry.
b
• Great deal of variability between:
– berries within a cluster
– clusters within a vine
– vines within a cultivar (clone)
– between vines within a vineyard
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9. 9/19/2012
Summary(cont.)
• Determination of berry ripeness can
be difficult due to variability.
• The main objective of the g
j grower is:
– achievement of a uniformly ripe crop
– with great flavor and aroma compounds.
Summary(cont.)
• The berry itself has three main tissues
that comprise it: flesh, skin, and seed.
• Each tissue contributes differently to
overall wine composition.
• Composition can be manipulated by changing
berry size
• Other factors such as the number of
seeds, environment, and nutrition also
affect final wine quality.
Summary(cont.)
•every one of these components is
tied initially to successful flower
fertilization.
•For the grape vine, reproduction is
the number one purpose to exist.
•Humans manipulate this process for
their benefit!
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10. 9/19/2012
Human
manipulation
of ripe
grapes
Hour exam next class!
• Worth 100 points
• Short answers
• Identify grape/grapevine parts
y g p g p p
• Study guide posted today(Thurs.) by
3pm
• Questions?
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