Chapter 2 The Vine Growth Cycle

Question 1

Define dormancy

Answer 1

A period during which the vine sustains Itself with carbohydrates stored in the roots, trunk and branches. It starts with leaf fall and ends with budburst in spring.

Question 2

Why does dormancy happens?

Answer 2

Average air temperatures below 10 ° C are too cold for the vine.
North: November – March
South: May - September

Question 3

Define budburst

Answer 3

The end of dormancy. Buds swell and open and green shoots start to emerge.
North: march-april
South: September – October

Question 4

What affects budburst?

Answer 4

• Air temperatures above or equal to 10° C.
• Higher soil temperatures because of dry free draining soil encourage budburst: sandy soils.
• Delaying pruning in winter can postpone budburst.
• Some varieties have different temperatures: early budding or late budding.

Question 5

Define shoot and leaf growth

Answer 5

The growth and development of shoots, buds, leaves and inflorescences. Vigor is the term that describe vegetative growth.

Question 6

How does shoot and leaf initially happens?

Answer 6

Initially thanks to the carbohydrates located in the roots, trunk and branches.

Question 7

Define vigour/ vigor

Answer 7

The growth of shoots, leaves and lateral shoots. Higher vigor- longer shoots and bigger leaves.

Question 8

What does vigour depends on?

Answer 8

Vigor depends on:
1. Resources available: temperature, water and nutrients.
2. Planting material: variety, clone, rootstock
3. Presence of disease.

Question 9

Define flowering

Answer 9

The development of flowers or inflorescences. The opening of individual flowers in an inflorescence. This leads to pollination. Pollen-landen stamens are exposed and the pollen lands on the stigma surface.

Question 10

What affects flowering?

Answer 10

Warm temperatures: minimum 17° C

Rain, clouds, wind and cold temperatures are adverse conditions.

Question 11

Define fruit set

Answer 11

The transformation of flowers into grapes through pollination and pollen germination.

Question 12

Explain fruit set?

Answer 12

After pollination individual pollen grains germinate and each grain transforms into a pollen tube. The pollen tubes penetrate the stigma and the ovule. The eggs are fertilized. This leads to the formation of a grape berry with up to 4 seeds (from the fertilized ovules) The wall of the ovary form the skin and pulp of the grape.

Question 13

Define bud fruitfulness

Answer 13

The number of inflorescences that will develop from a bud in the next growing season.

Question 14

Describe bud fruitfulness?

Answer 14

The conditions during the part of the growing season where the compound buds develop on the new shoots can have a substantial influence on the next year’s yield.

Question 15

Describe pollination

Answer 15

The process where pollen grains are shed by the male part of the flower and come in contact with the female part of the flower.

Question 16

How does pollination work?

Answer 16

The stamen (anther + filament) are full of pollen and exposed. The pollen grains are shed and land on the moistened stigma surface.

Question 17

Define coulure

Answer 17

A condition of the grape bunch in which a high proportion of flowers has had a failed fruit set.

Question 18

Why does coulure happens?

Answer 18

When ovule fertilization is unsuccessful and therefore no grape develops. It’s caused by a low level of carbohydrate due to:
1. Low rates of photosynthesis (cold, cloudy conditions or hot, arid conditions).
2. Vigorous shoot growth using too much carbohydrates. (fertile soils or use of fertiliser)
3. Some varieties are naturally susceptible

Question 19

Define millerandage

Answer 19

A condition where a high proportion of grapes are seedless and as a result smaller. Some grapes can stay green and unripe.

Question 20

Why does millerandage happen?

Answer 20

Cold, wet, windy weather during fruit set specially with some varieties.

Question 21

Define early grape growth

Answer 21

A stage during the growth cycle after fruit set. Hard green grapes start to grow. Shoot grow continues during grape growth but slower.

Question 22

What changes during grape growth?

Answer 22

1. Grapes grow in size.
2. Tartaric and malic acid accumulate.
3. Some aroma compound and aroma precursor develop.
4. Tannins accumulate. They are very bitter.
5. Water flows into the grape.

Question 23

What can prolong or speed up grape growth?

Answer 23

Prolong: too much water and nitrogen. They encourage shoot growth and delay grape repenting.

Speed up: mild water stress. This can lead to small grapes with more skin to pulp ratio. Can be good in some red wines.

Question 24

Define aromas precursors

Answer 24

Compounds with no aromas that will become aromas compounds during fermentation.

Question 25

How does aroma precursor work?

Answer 25

Through the process of fermentation some compounds that occur in a form combined with sugar as aromaless precursor, become aromatic.

Question 26

Define methoxypyrazines

Answer 26

An aroma compound that contributes to herbaceous aromas

Question 27

Define véraison

Answer 27

When grapes changes after grape growth.
- black varieties start to become red = synthesis of anthocyanins
- green colored chlorophyll in skin cell is broken down.
- the grape cell walls become stretchy and supple.

Question 28

Define ripening and its effects on grapes

Answer 28

The last stage before harvest.
1. Sugar accumulates in the grapes.
2. Concentration of tartaric acid falls due to more water and sugar in the grapes.
3. Malic acid concentración falls due to transpiration.
4. Methoxypyrazine levels fall.
5. Other aroma compounds increase.
6. In black grapes tannins decrease.
7. Anthocyanins increase.

Question 29

What can affect the ripeness of the grapes?

Answer 29

• grape variety
• climatic conditions
• management of the vine and vineyard
• time of harvest

Question 30

Define extra ripening

Answer 30

When grapes start to shrivel.

Question 31

Explain extra ripening?

Answer 31

• Water loss through transpiration concentrates sugar.
• extra ripe aromas develop.
• extra ripening is possible where weather conditions allow.

Question 32

How does the growth of the shoots affect the quality of the wine?

Answer 32

Slow growth can affect the quality and quantity of the grapes. Small shoots - less leaves - less inflorescences - smaller and unripe grape bunches.

Question 33

What affects bud fruitfulness?

Answer 33

Shading of compound buds, temperatures that are too low (under 25°C), water stress and nutrient deficiency can all limit bud fruitfulness