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Introduction to Vines and Wines

Hort/VE 113 Fall 2012Session 9-Grape Development and

ripeningripening

Grape Structure

A grape cluster is a complex flower, or inflorescence, that consists of a peduncle cap stems peduncle, cap stems (also called pedicels), a rachis, and berriesthat arise from individual flowers in the flower cluster.

• Each individual berry is made up of skin, flesh (or pulp), and seeds. On the outside of the skin is the bloom, or waxy

Grape Structure

ylayer, that helps to prevent water loss

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Vine growth stages

• Budbreak (leaf growth)

• Bloom• Berry set• 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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Flowering

Fruit set • follows flowering almost

immediately

• the fertilized flower begins to develop a seed and grape berry to protect the seed

In th N th M S th• In the North-May, South-November

• stage is very critical for wine production since it determines the potential crop yield

• Not every flower on the vine gets fertilized; unfertilized flowers eventually fall off the vine.

Photo credit:Fir0002/Flagstaffotos

• percentage of fertilized flowers 30 up to 60 or much lower.

Cli d i h l h

Fruit set

• Climate and vine health important!

• low humidity, high temperatures and water stress can severely reduce the number of flowers that get fertilized.

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“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• Can get out of hand

Bad weather (cold or hot) during and right after bloom can make this a problem!

‘Malbec’ sensitive to shattering

If it’s hot-faster shoot growth and more respirationUses up available carbohydrates normally devoted to grape development

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•BERRY DEVELOPMENT STARTS SOON AFTER FERTILIZATION OF THE FLOWER.

•CHARACTERIZED BY STRONG GROWTH OF THE SEED AND BERRY

Stage 1

•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

•ALSO KNOWN AS THE ‘LAG’ PHASE

•THE BERRY ITSELF GROWS SLOWLY

•DURING THIS PERIOD THE EMBRYO WITHIN THE SEED

Stage 2

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. 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).

•THE PERIOD OF RAPID CELL EXPANSION AND SUGAR ACCUMULATION.

•POTASSIUM, AMINO ACIDS AND PHENOLIC COMPOUNDS

Stage 3-Berry ripening

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

d h d and 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 – 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

• For the production of high quality wine, it is ideal to have an earlier veraison

• The vine is biologically programmed

Veraison onset

g y p gto:

– 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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• very vigorous vines – have lots of leaf

shading for photosynthesis and water supply

Controlling veraison onset

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 b berry.

• 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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• Determination of berry ripeness can be difficult due to variability.

• The main objective of the grower is:

Summary(cont.)

j g

– 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.

•every one of these components is tied initially to successful flower fertilization.

Summary(cont.)

•For the grape vine, reproduction is the number one purpose to exist.

•Humans manipulate this process for their benefit!

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Human manipulation of ripe grapes

Hour exam next class!• Worth 100 points

• Short answers

• Identify grape/grapevine partsy g p g p p

• Study guide posted today(Thurs.) by 3pm

• Questions?