2. The Vine Growth Cycle Flashcards
What are the 6 main steps of initial grape berry formation?
- Hard green grapes grow in size
- Tartaric and malic acids accumulate
- Tannins accumulate (very bitter)
- Some aroma compounds + precursors, e.g. methoxypyrazines + aroma precursors develop
- Sugar levels are low
- Water flow into grape is high
How can mild water stress during ripening benefit the production of red wine (2)?
- water stress => speeds up ripening of grapes vs. shoot growth.
- leads to smaller berries, reducing juice yield but increading skin : pulp ratio, giving higher concentrations of color/tannins/flavor and aroma compounds.
How do temps during the final month of ripening affect acidity in grapes (2)?
Why are some warm areas able to produce wines with higher acidity than others?
2 e.g.s?
Mean temps >21 C (70F) = rapid loss of acidity.
Mean temps <15 C (59F) = excess acidity in must might be too high.
Warm areas w/high diurnal range have cooler temps at night = less malic acid lost during respiration.
e.g. Central Otago, NZ + Columbia Valley, WA State.
How does the grape’s specific VARIETY influence the length of the growing season?
Give specific examples:
Certain varieties ripen earlier than others.
e.g. Chardonnay / Pinot Noir are EARLY-RIPENING
Cabernet Sauvignon / Grenache are LATE-RIPENING
What are methoxypyrazines?
In which varieties are they found?
Aroma compounds contributing to herbaceous, green bell pepper aromas/flavours. Typical varieties to feature these are Sauvignon Blanc, Cabernet Sauvignon and Cabernet Franc.
What are the 3 main changes in the composition of grapes during ripening?
- Sugar and water levels accumulate
- Tartaric and Malic Acid generally do not fall, but become less concentrated due to dilution
- Tannins, colour and aroma compounds develop
What can stunted shoot growth lead to (4)?
Small, weak shoots.
Reduction in leaf number/size.
Improper flowering (Coulure / Millerandage)
Poor Quality + lower yields.
What are the 4 stages of Grape Ripening?
- Grape Berry Formation
- Véraison
- Ripening
- Extra-Ripening
What determines whether a grape is EARLY or LATE BUDDING?
Give 3 examples of each:
- Budding times depend on the min. temperature at which buds open, i.e. the lower the min. temperature = the earlier the budding time.
EARLY: Chardonnay / Pinot Noir / Merlot / Grenache
LATE: Sauvignon Blanc / Cabernet Sauvignon / Syrah / Ugni Blanc
How do soil qualities affect budburst (2)?
Higher soil temps encourage earlier budburst.
Dry, free-draining (e.g. sandy) soils warm up more quickly than water-storing soils (e.g. clay).
Why does the presence of too much water and nitrogen prolong the Berry Formation stage or grape ripening?
What problems can this cause in the long run?
- these conditions promote vegetative/shoot growth over grape ripening.
- causes a delay in onset of ripening => possible insufficient time for ripening before weather becomes cold/rainy and grapes must be harvested.
What is coulure and when does it occur?
Condition whereby fruit set has failed for a high proportion of flowers.
Coulure occurs when fertilization fails to take place, and therefore, no grape develops.
What conditions are necessary for successful flowering to occur?
What conditions inhibit successful flowering?
- Warm temps (min. 17C / 63F) / Sunlight, Water, Nutrients, Warmth.
- Conditions that are Rainy / Windy / Cloudy / Cold Temps.
What affects development of anthocyanins during the ripening stage (2)?
- Anthocyanins increase during this stage.
- Increase speeds up w/plentiful sunlight and temps btw/15C (59F) - 25C (77F)
Describe the process of flowering and fertilization (7):
- Pollen-laden stamens are exposed and pollen grains are shed.
- Grains land on moistened stigma surface (pollination).
- Germination; each grain produces a pollen tube.
- Pollen tubes penetrate stigma and ovule in ovary.
- Pollen tube delivers sperm cells, fertilizing eggs in the ovule.
- Fertilized ovules form seeds.
- Ovary enlarges to form skin and pulp leads to formation of grape berry.
What is millerandage?
Also known as:
What causes it?
3 varietals that are particularly susceptible:
Condition whereby there is a high proportion of seedless grapes, and uneven ripening occurs (seedless berries can still ripen but are smaller.)
“Hens and Chicks”
Cold, wet and windy weather at fruit set and pollination.
Chardonnay / Merlot / Zinfandel
Using a specific example, explain how some aromas are more associated with varieties grown in certain climates (3):
Chardonnay in cool climates e.g. Chablis = green+citrus fruits
Chardonnay in warm climates e.g. Napa Valley = stone+tropical fruit.
Broadly speaking, warmer, sunnier climates = grapes/wines with “riper” aromas than cooler climates.
What are the 7 stages of vine growth cycle and in which months (Northern + Southern Hemisphere) do they occur?
1) Dormancy (Nov-Mar) / (May-Sept)
2) Budburst (Mar-Apr) / (Sept-Oct)
3) Shoot and Leaf Growth (Mar-July) / (Sept-Jan)
4) Flowering and Fruit Set (May-June) / (Nov-Dec)
5) Grape Development (June-Oct) / (Dec-Apr)
6) Harvest (Aug-Oct) / (Mar-Apr)
7) Leaf Fall and Dormancy (Nov-Dec) / (May-June)
How does the vine support initial shoot growth?
What determines the rate of shoot growth?
When is the fastest rate of growth?
Initial shoot growth is supported by carbs stored in roots, trunk and branches.
Rate of shoot growth is determined by vine vigor.
Fastest rate of growth = btw/budburst and flowering.
Explain the differences of water and sugar flow during the ripening stage (2):
How do climate conditions affect sugar accumulation in grapes?
What happens if conditions are too warm?
Water flow via the XYLEM slows down and a sugar solution is transported via the PHLOEM from leaves into the grape.
Accumulation of sugar in the grape = correlated to grape transpiration because water transpires through grape skin as sugar takes its place.
Sugar accumulation = higher in warm, dry conditions than cool, humid conditions.
In very warm conditions, sugar can accumulate too rapidly and reach high levels before aromas/flavors/tannins have fully developed.
Besides sunlight and carbohydrates, what do vines need for initial shoot growth (2)?
Nutrients (esp. nitrogen, potassium + phosphorous)
Water (water stress = limited photosynthesis + growth) + dry soils impairs nutrient uptake.
How does the CLIMATE influence the length of the growing season (2)?
- Sugar ripening is fastest in warm, dry climates, slower in cooler climates.
- However, conditions that are TOO hot/dry can cause the vine to shut down, inhibiting sugar formation/ripening.
Why are continental climates MORE advantageous for successful budburst (2)?
Why are maritime climates LESS advantageous for successful budburst (2)?
Continental climates = marked differences in temperature btw/ seasons.
Rapidly increasing temps in spring = uniform budburst, more homogenity of later stages, even ripeness.
Maritime climates = less distinct contrast btw/ winter+spring temps.
Budburst is less synchronized / unusually mild winter days can trigger early budburst followed by frosts that damage buds = lower yields.
How can shoot growth be negatively affected (5)?
If carb store levels are low due to:
excesive leaf removal / water stress / mildew infections / high crop loads in the previous season.
How does the vine support its growth during dormancy?
Why does it have to do this?
Stores of carbs (starch) accumulated during the previous growing season in the roots, trees and branches.
Since leaves fall off in the autumn, the vine has no way to photosynthesize and create sugars.
How do temperature levels affect the development of aroma compounds (3)?
During ripening, methoxypyrazine levels fall naturally, but cool temps and less sunlight (e.g. due to shading) can hinder decrease.
Resulting wines may be overly herbaceous/green.
Other aroma compounds+precursors (e.g. terpenes) also develop during ripening, and heat affects synthesis+development of these.
What is essential for respiration to occur?
In plants, what does the respiration process entail?
Warmth is necessary.
Respiration is the process in which energy is released from food i.e. sugar.
What are the HUMAN and NATURAL factors that determine the time of harvest?
HUMAN: Desired style of wine (e.g. different styles of Riesling) / logistics (e.g. availability of labor.)
NATURAL: Weather (e.g. rain) / Disease pressure.
What are aroma precursors?
Compounds with no aroma that will BECOME aroma compounds during the fermentation process.
What is flowering?
When does it typically take place?
Opening of the individual flowers within an inflorescence.
Typically occurs within 8 weeks of budburst.
What is fruit set?
What is the typical % of flowers that become grapes?
What conditions are needed for successful fruit set?
What are some inhibitors?
The transition from flower to grape.
Usually 30%, but can range from 0-60%.
NEEDS: Warm temps (26-32C / 79-90F)
INHIBITORS: Cool, wet, windy conditions negatively affect pollen tube growth = uneven fruit set. Conditions that are too HOT/DRY can lead to water stress, which can inhibit fruit set as well.
What are the 4 factors that influence length of ripening stage?
Grape variety
Climatic conditions
Management of vine/vineyard
Time of harvest
What are the 3 main stages of veraison?
- Grape growth slows down (aka “the lag phase”)
- Grape walls become more stretchy and supple
- Green chlorophyll in skin cells break down and grapes change color.
Why do wines from cooler climates tend to have higher natural acidity (3)?
Respiration is slower at cool temps than warm.
Malic acid can be used in respiration during ripening (before, sugar is used).
Cooler temps = less respiration = less malic acid lost.
What are the 5 things a vine needs?
Heat, sunlight, water, nutrients, CO2
What influences the amount of grape shrivelling that occurs during the Extra-Ripening stage (2)?
- Climate; most likely in hot, sunny, dry climates because of higher transpiration rate.
- Variety; certain grapes are more susceptible, e.g. Syrah
What are the causes of Coulure (4)?
Which grapes are more susceptible (4)?
- Caused by an imbalance in carbohydrate levels.
- Can be due to low photosynthesis levels (from cloudy, rainy conditions, as well as drought which causes the vine to shut down.)
- Also due to excessive shoot and vegetative growth diverting resources away from the grapes.
- Fertile soils, excess application of fertilizers and vigorous rootstocks can all lead to excess shoot growth, and thus coulure.
Grenache, Cabernet Sauvignon, Merlot, Malbec
What does bud fruitfulness refer to?
What are limiting factors to bud fruitfulness in the next growing season (5)?
No. of inflorescences that will develop from a bud.
Shading of compund buds / low temps (<25C / 77F) / water stress / nutrient deficiency:
DURING Flowering + Fruit Set
What is phloem?
Type of transport tissue that transfers sugars from leaves to other parts of vine.
Why are insects and wind only mildly important to pollination in grapevines?
Cultivated vines are normally self-pollinating, i.e. the pollen from the stamens of 1 flower polinates the stigma of the same flower, or a different flower in the same plant.
How does the vine support itself during dormancy?
What process is carried out by grape-growers during this period?
It survives off carbs via starch stored in roots / trunk / branches from the previous growing season.
Winter pruning.
How does CANOPY MANAGEMENT influence the length of the growing season (3)?
- Excessive shading
- Heavy crop loads
- lack of pruning of new shoots
ALL can slow down ripening.
What factors influence timing of budburst? (4)
Air temperature (needs to be above 10C / 50F)
Soil temperature (higher = earlier budburst)
Grape variety (early budding vs. late budding)
Human factors (ex. late winter pruning can postpone budburst)
What process causes the skins of red grapes to change color?
- Breakdown of chlorophyll in skin cells and synthesis of anthocyanins.
What’s a xylem?
Type of transport tissue that transfers water and some nutrients from roots to other parts of vine.
How do tannins in black grapes change during grape development (4)?
- in early stages, tannins are bitter, green and accumulate in skins, seeds and stems.
- level of tannins is high at véraison and decreases slightly throughout ripening.
- during ripening, tannins polymerize (bind together to form bigger chains) and become less bitter.
- sun exposure to grapes = more accumulation PRE-veraison and greater polymerization POST-veraison.
What are terpenes?
Aroma precursor compounds that give intensely floral aromas (e.g. Viognier, Gewurztraminer, Torrontés.)
How do grapevines behave in the wild (2)?
What is the purpose of grapes in the wild (2)?
What do grape growers manipulate the vine into doing?
- Vines are woodland climbers.
- W/out intervention, vines grow quickly, clinging to trees for support and only produce fruit once they reach sunlight at the top of the canopy.
In the wild, grapes attract birds/animals which eat the grapes and disseminate the seeds.
- Grapes are not actually suitable for wine.
Grape grower must manipulate vine into prioritizing grape production, in order to achieve adequate sugar, acid, tannin and aroma/flavor ripeness.
What temperature is it too cold for vines to grow? What temperature can cause vines to die?
Below 10 degrees Celsius (50F) is too cold to grow.
-15 degrees Celsius can cause vines to die.
Why are vines able to survive on limited natural resources?
Given their natural habitat in woodland locations, vines have adapted to having high competition with other plants.
