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.