Level 4 D1 Chap 2 - The Vine Growth Cycle

Question 1

Question

Answer 1

Answer

Question 2

List the phases of vine growth, starting in winter

Answer 2

1. Dormancy
2. Budburst
3. Shoot and leaf growth
4. Flowering and fruit set (8 weeks after budburst)
5. Grape Development
6. Harvest
7. Leaf fall (and back to dormancy)

Question 3

What resources does a vine need to survive?

Answer 3

1. Water
2. Sunlight
3. Warmth
4. Nutrients
5. Carbon Dioxide (a factor that growers cannot control)

Question 4

What average temperature gives rise to dormancy?

Answer 4

< 10°C

Question 5

What temperature kills most vines?

Answer 5

Vitis vinifera is killed below -25°C

Other vines may die at -20°C

Question 6

What average temperature gives rise to new growth (budburst) in the spring?

Answer 6

Budburst is triggered >10°C

Question 7

Compare the impact of a continental climate over maritime on budburst

Answer 7

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.

Question 8

Compare the impact of soil water retention on temperature and vine growth

Answer 8

Free draining soils hold less water, and heat up quicker encouraging earlier budburst and potentially earlier ripening.

Question 9

How and why do growers delay budburst?

Answer 9

Late winter pruning can delay budburst, to help avoid spring frost damage

Question 10

What does a vine need during its ‘shoot and leaf growth’ phase?

Answer 10

1. Carbohydrates (to get growth going)
2. Warmth
3. Sunlight (for photosynthesis to kick off)
4. Nutrients (thru roots)
5. Water

Question 11

What does a vine need to maximise flowering and fruit set?

Answer 11

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

Question 12

Name and describe the process by which flowers turn into grapes?

Answer 12

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.

Question 13

______ is a condition in which fruit set has failed for a high proportion of flowers.Describe its causes and name a susceptible variety

Answer 13

COULURE is a condition in which fruit set has failed for a high proportion of flowers

It is cause by

1. Carbohydrate imbalance
2. Low rates of photosynthesis (too cloudy/cold)
3. Water stress
4. Vigorous vegetative growth competing for resources (too much fertiliser)

Grenache, Cabernet Sauvignon, Merlot, Malbec

Question 14

What is coulure?

Answer 14

A high failure rate for fruit set

Question 15

______ is a condition in which there is a high proportion of seedless grapes.Describe its causes and name a susceptible variety

Answer 15

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

Question 16

What is millerandage?

Answer 16

Millerandage is a term for a high proportion of seedless, smaller grapes.

Question 17

What are the key stages of grape development?

Answer 17

1. Early grape growth
2. Veraison
3. Ripening
4. Extra-ripening

Question 18

What compounds accumulate during early grape growth?

Answer 18

• Tartaric acid
• Malic acid
• Aroma compounds/ precursors such as methoxypyrazines (herbaceous flavours)
• Tannins (bitter at this stage)

Question 19

What are methoxypyrazines?

Answer 19

Herbaceous flavoured compounds formed in some grape varieties.

May be found in Sauvignon Blanc, Cabernet Sauvignon, and Cabernet Franc

Question 20

What are anthocyanins?

Answer 20

Compounds that give black grapes their colour

Question 21

What compounds give black grapes their colour?

Answer 21

Anthocyanins

Question 22

What happens during grape ripening (post veraison)?

Answer 22

1. Shoot growth slows
2. Sugar and water accumulate
3. Tartaric and malic acid get diluted by water
   - malic acid is also metabolized in grape respiration (hence cool nights retain malic acid)
4. Tannins, color and aroma precursors & compounds develop
   - Anthocyanins accumulate in black grapes
   - Methoxypyrazine levels fall
   - Tannins polymerise (reduces bitterness)

Question 23

What are terpenes?

Answer 23

Terpenes are aroma compound that gives floral and citrus aromas. e.g. the grapey aroma in Muscat

Question 24

With respect to acid development, what is a good temperature range during ripening and why?

Answer 24

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.

Question 25

What happens during extra-ripening of grapes?

Answer 25

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)

Question 26

What is needed in vine during dormancy?

Answer 26

Carbohydrates stores in trunk, roots and branches – this starts the growth in the spring.

Question 27

What are early budding varieties?

Answer 27

The champagne duo:
Chardonnay
Pinot Noir

Also
Merlot
Grenache

Question 28

What are late budding varieties?

Answer 28

Think SOUTH FRANCE:
Cabernet Sauvignon
Syrah

Also
Sauvignon Blanc

Question 29

What temperature is needed for flowering?

Answer 29

> 17°C

Question 30

What happens during the veraison stage?

Answer 30

1. Grape growth slows - “the lag phase”
2. Grape cell walls become stretchy & supple
3. Green chlorophyll in skin cells break down.
4. Black grapes become red due to synthesis of anthocyanins.

Question 31

With respect to photosynthesis, what is a good temperature range during ripening and why?

Answer 31

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.