Level 4 D1 Chap 2 - The Vine Growth Cycle Flashcards
Question
Answer
List the phases of vine growth, starting in winter
- Dormancy
- Budburst
- Shoot and leaf growth
- Flowering and fruit set (8 weeks after budburst)
- Grape Development
- Harvest
- Leaf fall (and back to dormancy)
What resources does a vine need to survive?
- Water
- Sunlight
- Warmth
- Nutrients
- Carbon Dioxide (a factor that growers cannot control)
What average temperature gives rise to dormancy?
< 10°C
What temperature kills most vines?
Vitis vinifera is killed below -25°C
Other vines may die at -20°C
What average temperature gives rise to new growth (budburst) in the spring?
Budburst is triggered >10°C
Compare the impact of a continental climate over maritime on budburst
Continental climates: Sharper changes in temperature in continental systems, typically give rise to uniform budburst and ultimately ripening.
Maritime climates: There is a lower risk of frost damage from a cold spell after budburst, but budburst may not be as synchronized. Also a few unusually mild days can bring on budburst…and then a freeze may hit.
Compare the impact of soil water retention on temperature and vine growth
Free draining soils hold less water, and heat up quicker encouraging earlier budburst and potentially earlier ripening.
How and why do growers delay budburst?
Late winter pruning can delay budburst, to help avoid spring frost damage
What does a vine need during its ‘shoot and leaf growth’ phase?
- Carbohydrates (to get growth going)
- Warmth
- Sunlight (for photosynthesis to kick off)
- Nutrients (thru roots)
- Water
What does a vine need to maximise flowering and fruit set?
Current year buds:
- needs a minimum temperature of 17°C
- dry, calm days so that pollen is not washed away from the stigma, and can grow fertilisation tubes
For next year buds:
- sunlight
- water
- warmth
- nutrients
Name and describe the process by which flowers turn into grapes?
Name: Fruit set
Pollen grains land on the stigma and from there grow a tube into the ovary to deliver sperm cells that fertilise the vines eggs.
Fertilised eggs become seeds within grapes, and the walls of the ovary enlarge to form the pulp and the skin.
______ is a condition in which fruit set has failed for a high proportion of flowers.Describe its causes and name a susceptible variety
COULURE is a condition in which fruit set has failed for a high proportion of flowers
It is cause by
- Carbohydrate imbalance
- Low rates of photosynthesis (too cloudy/cold)
- Water stress
- Vigorous vegetative growth competing for resources (too much fertiliser)
Grenache, Cabernet Sauvignon, Merlot, Malbec
What is coulure?
A high failure rate for fruit set
______ is a condition in which there is a high proportion of seedless grapes.Describe its causes and name a susceptible variety
MILLERANDAGE is a condition in which there is a high proportion of seedless grapes.
It is caused by cold, wet weather at pollination and fruit set disrupting the growth of pollen tubes.
Chardonnay, Merlot
What is millerandage?
Millerandage is a term for a high proportion of seedless, smaller grapes.
What are the key stages of grape development?
- Early grape growth
- Veraison
- Ripening
- Extra-ripening
What compounds accumulate during early grape growth?
- Tartaric acid
- Malic acid
- Aroma compounds/ precursors such as methoxypyrazines (herbaceous flavours)
- Tannins (bitter at this stage)
What are methoxypyrazines?
Herbaceous flavoured compounds formed in some grape varieties.
May be found in Sauvignon Blanc, Cabernet Sauvignon, and Cabernet Franc
What are anthocyanins?
Compounds that give black grapes their colour
What compounds give black grapes their colour?
Anthocyanins
What happens during grape ripening (post veraison)?
- Shoot growth slows
- Sugar and water accumulate
- Tartaric and malic acid get diluted by water
- malic acid is also metabolized in grape respiration (hence cool nights retain malic acid) - Tannins, color and aroma precursors & compounds develop
- Anthocyanins accumulate in black grapes
- Methoxypyrazine levels fall
- Tannins polymerise (reduces bitterness)
What are terpenes?
Terpenes are aroma compound that gives floral and citrus aromas. e.g. the grapey aroma in Muscat
With respect to acid development, what is a good temperature range during ripening and why?
15°C to 21°C (depends on variety)
- Too low and malic acid levels remain high;
methoxypyrazine levels remain high. Grapes will be more herbacious and acidic.
Too high and lots of acid is lost. Grapes ripen too quickly and do not develop as many aroma compounds. Grapes will be sweeter and blander.
What happens during extra-ripening of grapes?
Grapes lose water thru transpiration and shrivel.
Sugars are concentrated.
Ripe aromas can develop (potentially good or bad depending on the variety and style of wine)
What is needed in vine during dormancy?
Carbohydrates stores in trunk, roots and branches – this starts the growth in the spring.
What are early budding varieties?
The champagne duo:
Chardonnay
Pinot Noir
Also
Merlot
Grenache
What are late budding varieties?
Think SOUTH FRANCE:
Cabernet Sauvignon
Syrah
Also
Sauvignon Blanc
What temperature is needed for flowering?
> 17°C
What happens during the veraison stage?
- Grape growth slows - “the lag phase”
- Grape cell walls become stretchy & supple
- Green chlorophyll in skin cells break down.
- Black grapes become red due to synthesis of anthocyanins.
With respect to photosynthesis, what is a good temperature range during ripening and why?
18°C - 33°C
Plus at least 1/3 full sunshine.
A cold, cloudy environment will result in less sugar.
Hot and dry will result in water stress and less sugar.
