D1: The Vine Flashcards
What are the four sections of the vine
- main shoots
- one year old wood
- permanent wood
- roots
What are the 6 components which make up the canopy/major structures of the main shoots?
- stem
- buds
- leaves
- lateral shoots
- tendrils
- inflorescences/grape bunches
Where do the main shoots on the vine grow from?
buds retained from the previous year
What is the stems job?
- what all other structures are attached to
- transports water and solutes to and from different structures
- stores carbs
what are solutes?
- substances that dissolve in a liquid to form a solution e.g. sugars and minerals
what are nodes?
swellings along the stem where other structures attach
what is an internode?
length of stem between nodes
what does ‘lignify’ mean?
- green shoots become woody and rigid
- happens in late summer when leaves fall from vine
- shoots turn brown
- from then on become known as ‘canes’
Buds
- form between the leaf stalk and the stem
- when they mature: contain all structures that become green parts of vine
- two types: COMPOUND and PROMPT
What is a ‘compound bud’
- aka LATENT BUD
- form in one growing season and break open in next growing season to produce main shoots
- within compound bud, get primary, secondary and tertiary buds
- second and tertiary buds only grow if primary bud damaged
What is a ‘prompt bud’
- form and break open in same growing season
- form on main shoot and produce lateral shoots
What is a ‘lateral shoot’
- grow from buds formed in current year (prompt buds)
- have stem, leaves, buds, tendrils, inflorescences
- main function: allow plant to carry on growing if tip of main shoot has been damaged or eaten
- provide additional source of leaves for photosyn
- growing too close to base of main shoot is bad as can impede air flow and shade fruit too much
- can produce inflorescences - depends on grape variety though
what grape variety produces inflorescences on lateral shoots?
Pinot Noir
What is a ‘second crop’
- Where inflorescences are formed on lateral shoots
- become bunches later than those on main shoots and ripen later
- will be higher in acid, lower in alc and have unripe tannins if harvested at same time as normal crop
- can be removed in green harvesting
- if not and are picked during harvest, can have impact on must
What are tendrils
- curl around trellis wires and keep canopy in place
- growers often tie canes and shoots to trellis wires as a precaution as well!
Describe process of photosynthesis
- leaves are main site of photosynthesis in vine
- need sugars from photosyn to support vine growth and metabolism
- stomata open on underside of leaves
- lets water diffuse out and CO2 for PS to enter
- as water diffuses out, transpiration occurs drawing water and nutrients from soil up through vine to leaves
- stomata will partially close if vine is water stressed - limits photosyn by preventing CO2 from entering vine
What are inflorescences
- cluster of flowers on stem which becomes bunch of grapes at fruit set
- usually between 1 and 3 on main shoot
What are bunches
- fertilised inflorescence
- not all flowers in inflorescence will become grapes
- huge variation in grape varieties
EXAMPLE: Pinot noir has tight bunches so makes it more prone to fungal disease due to damage to grape skins
What are grapes made up of?
- pulp
- skin
- seeds
Pulp
- makes up majority of grapes weight and volume
- mostly colourless
- contains:
1. water
2. sugar
3. acid
4. aroma compounds and precursors
What are grapes with red pulp called?
Teinturier varieties
e.g. Alicante Bouschet
Grape Skin
- contains:
1. high concentration of aroma compounds and precursors
2. tannins
3. colour compounds
Grape Seeds
- Contains:
1. oils
2. tannins
3. embryon
What is the powdery, waxy coating on a grape called?
Bloom
- covers surface of grape
How is a grape attached to the vine?
- by a stem
- stem contains tannins
What is ‘one year old wood’?
- main shoots from last growing season which were kept at pruning
- OYO wood supports compound buds
- will either be called ‘cane’ or ‘spur’ depending on pruning techniques
What is ‘permanent wood’?
- woody parts of wine older than one year
- includes trunk
- may have one or more horizontal arms of perm wood called ‘cordons’
What is the role of the trunk and cordons?
- provide support for other parts of vine
- transport water and solutes to and from diff parts of vine
- store carbs
What is the role of the roots?
- anchor vine
- imp for uptake of water and nutrients
- store carbs
- produce hormones which are imp for vine growth and grape ripening
- usually found in top 50cm of soil
- can go deeper but depends on soil, irrigation, cultivation etc
Where are water and nutrients absorbed?
root tips where roots are actively growing
How are vines propagated?
by layerings or cuttings
- create genetically identical plants to parent plant
What is a cutting?
A selection of vine shoot that is planed and then grows as a new plant
- most common technique as can take many cuttings and can propogate all at same time
- can use rootstocks so can be easily grafted onto vine cutting before being planted
- nurseries can treat cuttings to avoid spread of disease
What is layering?
- use shoots from established neighbouring vine to produce new vine
- cane is bent down and section is buried in ground with tip of cane pointing out of ground
- buried section takes root and once roots are established, cane can be cut
- vine grows on its own roots so not on rootstock so no phylloxera protection
What is a clone?
- vines that are genetically identical to parent vine
What are the risks associated with clones?
- can get cell division during plant growth which causes random mutations in genetic code to occur
- can cause some slight changes in characteristics - e.g. thicker skins, smaller grapes etc
- causes diversity within vines of same grape variety
What is clonal selection?
- vines with favourable characteristics are selected by nurseries or grape growers for propagation by cuttings so as to grow new vines with these favourable characteristics
What grape varieties are known for clonal selection?
Pinot Noir
- 115: low yields, small grapes, good for high quality red wine
- 521: high yields, bigger grapes, good for sparkling wine as don’t need high concentration of tannins and colour from skins
what is the most common way of obtaining new planting material?
- buy young vines from nurseries
Benefits:
- usually have been tested for disease and viruses
- uniformity across the region
- good for vineyard management as grapes grow in similar way and ripen at same time
Negatives
- may only have a few available to choose from
- clones may have been chosen for maximising yield rather than quality
- less diversity in fruit so wine less complex and balanced
- risk of disease as vines likely to all be susceptible to same pest
- reasons above why a grower will want to buy and grow number of different clones of same variety
What is ‘mass selection’
AKA ‘selection massale’
- vineyard owners take cuttings from vines in their own vineyards and cultivate them
- can be sent to nursery to be grafted onto rootstock
- cuttings taken from different vines - often the best performing - and have been monitored for several years
Advantages:
- increases diversity of planting material in vineyard and region
- using own unique planting material so can enhance quality and/or yield
Disadvantages:
- monitoring can be costly (time and labour)
- can increase spread of disease as infected parent vines can pass disease onto new vines
How are new grape varieties produced?
- seeds
- pollen from stamens of flower of one vine is transferred to stigmas of flowers of another vine
- fertilisation occurs - called ‘cross fertilisation’
- grapes develop and seeds from these planted are planted and grown
- New vines grow from seeds and will all have different characteristics (look at parents and siblings - all look different)
- if vine is desirable, can take propagated by cuttings to create new identical vines
- potential and value assessed over long period
- if good, registered with the OIV catalogue as new grape variety
What is a ‘crossing’ and give an example
two parent vines are the same species
EXAMPLE: Pinotage = Pinot Noir x Cinsault
What is a ‘hybrid’ and give an example
two parent vines are from a different species
EXAMPLE: Vidal Blanc = Ugni Blanc x member of Seibel family
Hybrids created to attempt to combine resistance of non-vinifera species and quality of fruit from VV
Cross Fertilisation
- likely to have happened in the wild
- EXAMPLE: Cab Sauv came from cross fertilisation with Sauv B and Cab Franc
Scientists now try and do this in labs to try and create an offspring with favourable characteristics of both parent vines
- EXAMPLE: Muller-Thurgau = Riesling (fruit quality) x Madeleine Royale (high yield)
Vine Growth Cycle - Northern Hemisphere
- Dormancy: Jan to March
- Budburst: March to April
- Shoot and Leaf Growth: March to July
- Flowering and Fruit Set: May to June
- Grape Development: June to October
- Harvest: September to October
- Leaf fall and Dormancy: November and December
Vine Growth Cycle - Southern Hemisphere
- Dormancy: July to September
- Budburst: September to October
- Shoot and Leaf Growth: September to January
- Flowering and Fruit Set: November to December
- Grape Development: December to April
- Harvest: March to April
- Leaf fall and Dormancy: May and June
What does the vine need
- adequate water (for photosyn)
- sunlight (for photosyn)
- warmth (for photosyn; respiration)
- nutrients (for cell structure, function, vine growth and reproduction)
- adequate levels of CO2
**timing of these key to ensure vine can produce suitable grapes for wine
Dormancy
Nov to March (N)
May to Sept (S)
- temps below 10 degrees mean vine cannot grow so goes dormant
- leaves fall in autumn and ends with budburst in spring
- no leaves = no photosyn so vine has to use stored carbs
- winter pruning carried out in this period
At what temperatures are vines damaged during dormancy?
- 15 degrees
- found in Canada, New York State, China
- below -25 degrees will kill most VV
Budburst
- marks end of winter dormancy
- buds swell and open and green shoots start to emerge
- timing depends on AIR TEMP; SOIL TEMP; GRAPE VARIETY; HUMAN FACTORS
- vine needs av temps to be above 10 degrees and for there to be no cold soils or frost
Budburst: Air temperature
- need high temps for successful budburst. E.g. consistently over 10 degrees
- marked temp differences = beneficial. Budburst is relatively uniform which is good for the rest of the growing season
- little temp differences can make budburst less synchronised and budburst can happen too early so the new buds end up being damaged by frosts which means lower yields
Budburst: soil temperature
- higher soil temps around the roots encourage earlier budburst
- sandy soils warm up quicker than clay soils so these are good in cooler climate when earlier budburst improves chances of longer ripening period
Budburst: grape varieties
av temp required depends on grape variety
Those requiring low temps = early budding
- Chardonnay, Merlot, Pinot Noir, Grenache
Those requiring higher temps = late budding
- Sauv B, Cab Sauv, Syrah
- these are less at risk of spring frosts
Budburst: Human Factors
- can do some viticulutral practices to delay budburst
- e.g. carrying out winter pruning late to delay budburst. Often done where spring frosts are a problem
Shoot and Leaf Growth
- spring and early summer
- shoots continue to grow and leaves and inflorescences mature
- fastest rate of growth in this stage (depends on vigour of vine)
Vine needs:
- Stored carbs (v.imp)
- warmth, sunlight
- nutrients
- water (don’t want water stress)
Shoot and Leaf Growth: Role of Carbs
- Carbs stored in roots, trunks and branches of vine supports initial shoot growth
- low levels negatively impact shoot growth
Shoot and Leaf Growth: Leaves
- provide energy for further growth via photosyn
- need adequate warmth and sunlight for this to take place
Shoot and Leaf Growth: Nutrients
- needs NITROGEN, POTASSIUM, PHOSPHOROUS
- needs nutrients at this stage of the growth cycle
- very dry soils can impact nutrient uptake
What is the impact of stunted shoot growth during Shoot and Leaf Growth
- small, weak shoots
- reduction in leaf numbers
- smaller leaves
- bunches don’t fully ripen
- poor quality
- lower yields
Flowering and Fruit Set: what does the vine need during this period?
- warm temps (min 17 degrees)
- sunlight
- warmth
- water
- nutrients
Bad:
- rain
- cloud
- wind
- cold temps
***conditions at F+FS can impact/influence next years yield (exception: Riesling - can form fruitful buds at low temps)
Flowering and fruit set: where to new buds develop?
- base of leaf stalks on new growing shoots
- prompt buds become lateral shoots
- compound buds remain dormant until next spring
Risks which can limit bud fruitfulness in next growing season:
- shade
- low temps
- water stress
- nutrient deficiency
Outline the flowering process
- pollen-laden stamens are exposed
- pollen grains shed and land on moistened stigma surface (POLLINATION)
- Germination - each pollen grain produces a pollen tube
- pollen tubes penetrate stigma and then the ovule in the ovary
- leads to formation of a grape berry
- fertilised ovules form seeds (max of 4 per grape)
- wall of ovary enlarges to form skin and pulp of grape
What is the definition of ‘fruit set’?
- term used to describe transition from flower to grape
What are the conditions for successful flowering?
- usually within 8 weeks of budburst
- temperature dependent
- needs to be warm (min 17 degrees) where flowering begins within days
- too cold lengthens flowering and can lead to uneven ripening
What are the conditions for successful fruit set?
- typically 30% flowers become grapes (between 0% and 60%)
- germination needs warmer temperatures (20 - 32 degrees)
- pollen tube growth can be negatively affected by cold, wind, rain - leads to irregular fruit set and poor yields
- hot, dry, windy conditions = water stress = reduced yields
Coulure
- means irregular fruit set
- fruit set has failed for a high proportion of flowers
- ovule fertilisation has been unsuccessful so no grapes develop
- caused by
- imbalance of carb levels (low photosyn rate)
- poor weather conditions
- too vigorous shoot growth (diverting carbs from inflorescences)
Best conditions:
- fertile soils
- fertiliser
- vigorous rootstocks
- grenache, merlot, cab, malbec: all susceptible
Millerandage
- means irregular fruit set
- high proportion of seedless grapes
- can still ripen but are very small and therefore reduce volume of wine that can be produced
- can stay small, green and unripe so poor quality wine produced
- mainly from cold, wet, windy weather at pollination and fruit set
- chardonnay and merlot particularly susceptible
Grape Development Stage One: Grape Berry Formation
- starts soon after fruit set
1. hard green grapes grow and tartaric and malic acids accumulate
2. Aroma Compounds and Precursors develop (e.g. methoxypyrazines)
3. tannins accumulate. V bitter. Sunshine promotes tannin accumulation
4. sugar levels are low
5. water flow into grapes is high and mainly transported via xylem - too much water and nutrients can prolong this stage as can encourage shoot growth rather than grape ripening
- mild water stress can speed up stage. Will give reduced yield but has greater skin to pulp ration. Good for red wine as increases CAT compounds
- shoot growth continues but is slower at this stage
-
Grape development Stage 2: Veraison
- lag phase as growth slows for a few days
- cell walls become stretchy and supple
- green chlorophyll in skin cells breaks down
- black varieties start becoming red which is due to synthesis of compounds called ANTHOCYANINS
Grape Development Stage 3: Ripening
- most important stage in vine process as determines final grape quality
- shoot growth has slowed down
- cells in grape expand rapidly
- sugar and water accumulate
- acid levels fall
- tannins, colour and some aroma compounds and precursors develop
- harvest marks end of this stage
Grape Development Stage 3: Ripening
SUGAR ACCUMULATION
- rapid at start but then does slow down
- sugar produced via photosyn
- needs:
- max temps of 18 - 35 degrees
- sunlight levels above 1/3 of full sunshine
cold/cloudy = rate of photosyn hinders sugar levels
too hot/dry = extreme water stress causes photosyn to slow or stop and hinders sugar accumulation
Grape Development Stage 3: Ripening
WATER FLOW
- flow via xylem slows down
- sugar solution transported by phloem into grape
- movement of sugar solution and therefore sugar accumulation correlates to rate of grape transpiration
- faster in warm, dry conditions rather than cool, humid conditions
- movement of sugar solution and therefore sugar accumulation correlates to rate of grape transpiration
RISK: in warm environments, accumulation of sugar can be too quick and be too high before aromas/flavours/tannins have developed
Grape Development Stage 3: Ripening
TARTARIC ACID
- concentration falls during ripening due to dilution (as sugar and water accumulate in grape)
- MALIC ACID falls even more as used in respiration during ripening
- respiration is slower at cooler temps so therefore wines from cooler climates have higher acidity
Grape Development Stage 3: Ripening
TEMPERATURE
- temps above 21 degrees in final months can lead to loss of acidity
- temps below 15 degrees can mean acidity is too high
- cool night temps mean less malic acid lost during respiration - e.g. high diurnal range wines (central otago, washington state etc) have higher acidity than those with warmer night temps
Grape Development Stage 3: Ripening
AROMAS
- methoxypyrazine levels fall
- cool temps and lack of sunlight hinder decrease so very herbaceous or floral aromas
- other aroma compounds and precursors increase during ripening
- e.g. TERPENES - gives floral and citrus aromas
Impact of grape variety and natural resources on aroma compounds and precursors is very complicated but tasting shows that some aromas are more common to certain compounds - e.g.
Cool climate chardonnay = green and citrus fruit
Warm climate chardonnay = tropical and stone fruit
Grape Development Stage 3: Ripening
TANNINS
- levels high at veraison
- decrease during ripening
- sunshine promotes tannin accumulation pre-veraision and greater polymerisation post-veraison
- anthocyanins increase during ripening
What is the length of ripening dependent on?
- grape variety (early or late ripening)
- climate conditions (too warm or too hot)
- management of vine and vineyard (e.g. canopy management)
- time of harvest (both natural and human impact)
Grape Development Stage 4: Extra Ripening
- if left on vines, grapes start to shrivel
- no more sugar or water brought to grape so water lost through transpiration which concentrates sugars
- extra ripe aromas develop
Defining Ripeness
depends on number of factors
- level of sugars in grape
- dry wines: amount of sugar is directly linked to % alc
- sweet wines: sugar influences sweetness and alc - taste profile
- can be particular to individual grape grower
- dont want under-ripe herbaceous aromas or over-cooked jammy aromas - tannin ripeness
- want to avoid bitter, unripe tannins
- tannins polymerise during ripening and become less bitter
- sensation of tannins in finished wine is v complex
- other compounds can change perception
residual sugar = tannins seem softer
bone dry, high acid = tannins seem astringent
How do you define optimal ripeness?
- time when sugar, tannin and aroma ripeness most favourable
- want to produce balanced wine
- can make adjustments in winery
How are sugars, aroma compounds and tannins influenced by the growing environment?
- cooler conditions = slower process as too cold or shady means that grapes can struggle to meet sugar ripeness
- diff temps influence aromas as they either synthesise, degrade or retain aromas
- warm climates = sugar ripeness may be reached before aroma or tannin ripeness
