D1C01 The Vine

Question 1

What is Vitis Vinifera?

Answer 1

V. Vinifera is a vine species, to which belong the majority of known grape varieties. It’s indigenous to Eurasia.

Question 2

Name 4 North American vine species?

Answer 2

1. V. Labrusca
2. V. Riparia (Coast vine)
3. V. Berlandieri (Lime vine)
4. V. Rupestris (Rock vine)

Question 3

What is the function of North American vine species?

Answer 3

Rootstocks onto which V. vinifera is grafted.

Also used in wine production in some regions (e.g. New York State).

Question 4

Describe the 4 sections of the vine’s structure

Answer 4

1. main shoots
2. one-year-old wood
3. permanent wood
4. the roots

Question 5

Define the canopy

Answer 5

The main shoots and all of their major structures – stem, buds, leaves, lateral shoots, tendrils and inflorescences/grape bunches are collectively called the canopy.

Question 6

Describe the major structures of main shoots

Answer 6

1. stem
2. buds
3. leaves
4. lateral shoots
5. tendrils
6. inflorescences/grape bunches.

Question 7

What is the function of the stem?

Answer 7

The stem is essentially the structure to which all the other structures are attached.

It transports water and solutes to and from the different structures.

The stem is also a store of carbohydrates.

Question 8

What are canes?

Answer 8

In late summer, the leaves fall from the vine and the green shoots lignify (become woody and rigid) and turn brown; from this point they are called canes.

Question 9

Where do buds form and what do they become?

Answer 9

Form between leaf stalk (petiole) and stem – with maturation, become green parts of vine

Question 10

What structures do buds contain as they mature?

Answer 10

Buds contain all the structures in miniature that will become green parts of the vine, including the stem, buds, tendrils, leaves and often inflorescences.

Question 11

What are main types of buds?

Answer 11

1. Compound buds (also called latent buds)
2. Prompt buds

Question 12

When are compound buds formed and break open?

Answer 12

Compound buds (also called latent buds) form in one growing season and break open in the next growing season (provided they are retained during winter pruning).

Question 13

What is the function of compound buds?

Answer 13

Compound buds produce the main shoots in the next growing season.

Question 14

What is the structure of compound buds?

Answer 14

Compound buds have a primary bud (the main growing point) and smaller secondary and tertiary buds.

Question 15

What is the function of secondary and tertiary buds?

Answer 15

The secondary and tertiary buds serve as additional growing points. They usually only grow if damage has occurred to the primary bud (e.g. spring frost).

Question 16

When are prompt buds formed and break open?

Answer 16

Prompt buds form and break open in the same growing season.

Question 17

Where are prompt buds formed and what do they form?

Answer 17

They form on the main shoot (that has just grown from a compound bud) and produce lateral shoots.

Question 18

What are lateral shoots?

Answer 18

Grow from prompt buds.

Lateral shoots are smaller and thinner than the main shoots. Lateral shoots have a stem, leaves, buds, tendrils and sometimes inflorescences.

Question 19

Where do lateral shoots grow from?

Answer 19

Lateral shoots grow from buds formed in the current year (prompt buds).

Question 20

What is the function of lateral shoots?

Answer 20

Their main function is to allow the plant to carry on growing if the tip of the main shoot has been damaged or eaten.

Lateral shoots can provide an additional source of leaves for photosynthesis, which can be useful if the laterals are near the ends of the main shoots and able to benefit from sunlight.

Question 21

What is photosynthesis?

Answer 21

The process by which green plants use sunlight to produce sugars from carbon dioxide and water:

CO₂ + 2 H₂O + photons → CH₂O + O₂ + H₂O

(CH₂O being carbohydrates, e.g. sugar)

Question 22

Explain why growth of laterals nearer the base of the main shoot is undesirable?

Answer 22

As laterals impede air flow and can shade the fruit too much. They may be removed in summer pruning

Question 23

Define ‘second crop’.

Answer 23

Lateral shoots often produce inflorescences, which can be known as a ‘second crop’. These inflorescences become bunches of grapes later than those on the main stem and hence ripen later.

Question 24

Explain the difference between the bunches of the main crop and the second crop, if harvested at the same time.

Answer 24

If harvested at the same time as the main crop, the bunches in the second crop will be higher in acidity, lower in potential alcohol and may have unripe tannins and aromas/flavours and, in black grapes, less colour development.

Question 25

What is green harvesting and explain why it may be desirable?

Answer 25

Green harvesting is the removal of the second crop during the growing season.

This technique is thought to enhance the ripening process and improve the uniformity of ripeness of the remaining bunches.

Question 26

Would you advise green harvesting when hand harvesting?

Answer 26

If fruit is hand-harvested, the ability to be selective means the second crop need not be picked or can be separated.

Question 27

Explain the effects of the second crop when machine harvesting?

Answer 27

A vine grower can not avoid picking up green crop, and therefore it may have an impact on the must and finished wine.

Question 28

What are tendrils?

Answer 28

The shoot cannot support itself, therefore vines have tendrils. Tendrils attach the vine to other plants or trees, providing support

Question 29

What are the functions of tendrils in viticulture?

Answer 29

In viticulture, grape growers can use a trellis to position the vine canopy. The tendrils curl around trellis wires and keep the canopy in place.

Question 30

What is the function of leaves?

Answer 30

The leaves are the main site of photosynthesis in the vine.

The sugars produced in photosynthesis are used for vine growth and metabolism.

Question 31

Define stomata

Answer 31

Stomata are pores, found in the epidermis of leaves, stems, and other organs, that facilitate gas exchange.

Question 32

What’s the function of stomata?

Answer 32

Stomata (pores) open on the underside of the leaves, letting water diffuse out and carbon dioxide for photosynthesis to enter.

Question 33

Define transpiration

Answer 33

Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers.

As water diffuses from the leaf, transpiration draws water and nutrients from the soil up through the vine to the leaves.

Question 34

When do stomata close? Why?

Answer 34

Stomata partially close if the vine is water stressed. This can help conserve water, but limits photosynthesis by preventing carbon dioxide from entering the vine

Question 35

What are inflorescences?

Answer 35

The inflorescence is a cluster of flowers on a stem, which becomes a bunch of grapes at fruit set.

Question 36

What is the average number of inflorescences?

Answer 36

The number of inflorescences on each main shoot can depend on the grape variety, but is usually between one and three.

Question 37

What are bunches?

Answer 37

A bunch of grapes is a fertilised inflorescence.

Question 38

What are the risk of tight bunches?

Answer 38

Some grape varieties can have very tight bunches (e.g. Pinot Noir), which are more prone to fungal diseases inside the bunch due to damage to the grape skins.

Question 39

What is a grape?

Answer 39

A grape is a type of berry and is made up of pulp, skin and seeds.

Question 40

What compounds are found in the pulp?

Answer 40

The pulp contains water, sugars, acids and some aroma compounds and aroma precursors.

The pulp makes up the majority of the grape’s weight and volume and in most grapes is colourless.

Question 41

How are grapes with red coloured pulp called?

Answer 41

Teinturiers

These varieties are not very common. An example is Alicante Bouschet

Question 42

What compounds are found in the skin?

Answer 42

The skin of the grape contains a high concentration of aroma compounds and aroma precursors, tannins and colour compounds.

The amount of tannins and colour in black grapes is significantly higher than in white grapes.

Question 43

What compounds are found in the seeds?

Answer 43

Seeds contain oils, tannins and the embryo, which can grow into a new plant.

Seeds mature inside the grape, turning yellow to dark brown.

Question 44

What is the bloom?

Answer 44

Bloom is a powdery waxy coating, that covers the surface of the grape.

Question 45

Define one-year-old wood.

Answer 45

One-year-old wood refers to the main shoots from the last growing season that were kept at pruning.

Question 46

What does the amount of one-year-old wood depend on?

Answer 46

The amount of one-year-old wood will depend on the pruning and training decisions made by the grape grower.

Question 47

What’s the function of one-year-old wood?

Answer 47

Importantly, the one-year-old wood supports the compound buds that will break to release the main shoots for the upcoming growing season.

Question 48

What are the two main pruning techniques for one-year-old wood?

Answer 48

1. cane-pruned
2. spur-pruned.

Question 49

What is permanent wood?

Answer 49

These are the woody parts of the vine that are older than one year, including the trunk.

Question 50

What are cordons?

Answer 50

Depending on pruning and training decisions, some vines also have one or more horizontal arms of permanent wood, often called cordons.

Question 51

What are the functions of cordons and the trunk in permanent wood?

Answer 51

Cordons and the trunk in permanent wood provide support for the other parts of the vine.

Transport water and solutes to and from different parts of the vine and store carbohydrates and nutrients.

Question 52

What are the functions of roots?

Answer 52

1. anchoring the vine
2. provide uptake of water and nutrients;
3. store carbohydrates
4. produce hormones that have important functions within vine growth and grape ripening

Question 53

What is the distribution of the main framework of roots influenced by?

Answer 53

By the soil properties, irrigation, cultivation and the type of rootstock.

Question 54

How deep can vine roots grow?

Answer 54

Most of the vine’s roots are found in the top 50 cm of the soil, although vine roots have been found that reach over six metres down into the soil.

Question 55

Why are root tips important?

Answer 55

The water and nutrients are absorbed at the root tips, where the roots are actively growing.

Question 56

What are the main types of vine propagation in modern Viticulture?

Answer 56

1. Cuttings
2. Layering

Question 57

Define a cutting.

Answer 57

A cutting is a section of a vine shoot that is planted and then grows as a new plant.

Question 58

What are the advantages of cutting?

Answer 58

Cutting is the most common propagation technique, due to:

1. many small cuttings can be taken from a vine and propagated at the same time
2. it permits the use of rootstocks, which can easily be grafted onto the vine cutting before it is planted
3. nurseries are able to treat vine cuttings to avoid spread of diseases.

Question 59

What’s layering?

Answer 59

Layering is a method of filling gaps in a vineyard (e.g. due to the death of a vine) by using shoots from an established neighbouring vine to produce a new vine.

Question 60

Describe the layering technique?

Answer 60

A cane is bent down and a section of it is buried in the ground. The tip of the cane points up out of the ground. The section that is buried takes root. Once new roots are established, the cane linking the new growth to the original plant is cut.

Question 61

What are the main disadvantages of layering?

Answer 61

1. The new vine grows on its own roots, not those of a rootstock, and this method is therefore not always suitable.
2. The new vine will have no protection against phylloxera or have the qualities (such as the desired yield) that a choice of rootstocks offers

Question 62

Why are vines commonly propagated by cutting and layering techniques?

Answer 62

They create new plants that are usually genetically identical to the parent plant, and have the same characteristics.

Importantly, in viticulture, vines are not propagated through seeds.

Question 63

Why is seed propagation NOT used in Viticulture?

Answer 63

Vines that grow through seeds are not genetically identical to the parent vines and although they can show similar characteristics to their parents, more often they are notably different.

Question 64

What causes diversity within the vines of the same grape variety?

Answer 64

Random mutations in the genetic code at each cell division during plant growth.

Many of these mutations have no effect on the vine; however, some will cause the new vine to have slightly different characteristics (e.g. smaller or larger grapes, thicker or thinner grape skins, more or less disease resistance, etc.).

Question 65

What is clonal selection?

Answer 65

Selecting a SINGLE plant with the most favorable characteristics for propagation by cuttings

Vines with favourable characteristics are selected by vine nurseries or grape growers for propagation by cuttings in order to grow new vines with these favourable characteristics.

Question 66

What is a vine clone? Give an example.

Answer 66

It’s a vine genetically identical to the parent vine, with slightly different characteristics occurring due to mutations.

Pinot Noir is a grape variety with many clones.

Question 67

When can a new grape variety appear? Give an example.

Answer 67

On rare occasions, a mutation might be so significant that the new vine is classified as a new grape variety. For example, Pinot Noir, Pinot Meunier, Pinot Blanc and Pinot Gris are all mutations of the grape variety Pinot.

Question 68

What are advantages and disadvantages of clonal selection?

Answer 68

1. • have been tested to be free from virus infection by nurseries
2. • only a very limited number of clones may be available from nurseries
3. • creates relatively uniform vineyard, especially if natural factors are consistent across the region
4. • management of the vineyard becomes simpler, if all of the vines grow in a similar way and ripen grapes at the same time
5. • less diversity in the fruit and hence potentially producing a wine with less complexity and balance
6. • makes the vineyard more susceptible to disease (the identical vines are likely to all be equally susceptible to a disease or pest).

Question 69

Define mass selection?

Answer 69

Cuttings from SEVERAL different vines, also termed Selection Massale.

The technique requires vineyard owners to take cuttings from the vines in their own vineyard(s) and cultivate these cuttings.

Cuttings are taken from several different vines. Generally, the best-performing vines are selected (e.g. those that consistently yield fruit with the desired characteristics). These vines are selected after several years of monitoring and recording their performance.

Question 70

What are advantages and disadvantages of mass selection?

Answer 70

1. • increased diversity of planting material in the vineyard and throughout the region
2. • enhanced fruit quality and/or yield (as the vineyard owner is using their own unique planting material
3. • costly in terms of time and labour (the selection and monitoring of best vines)
4. • can increase the spread of vine diseases (if the parent vine is infected by disease (e.g. a virus).

Question 71

How are new grape varieties produced?

Answer 71

From seeds

Question 72

What is cross fertilisation?

Answer 72

The pollen from the stamens of the flowers of ONE vine is transferred to the stigmas of the flowers of ANOTHER vine and fertilisation occurs.

It is thought that many grape varieties with a long history of cultivation were created through cross fertilisation that happened by chance in the wild.

Cabernet Sauvignon was formed by a chance cross fertilisation of Sauvignon Blanc and Cabernet Franc.

Question 73

What is a crossing?

Answer 73

When the two parent vines are from the same species. For example, Pinotage is a cross of Pinot Noir and Cinsault.

Question 74

What is a hybrid?

Answer 74

When the two parent vines are from different species.

Vidal Blanc, from Ugni Blanc (V. vinifera) and a member of the Seibel family (American parentage).

Question 75

Give example of new grape varieties formed by cross fertilization in the wild and in a laboratory?

Answer 75

in the wild:

• Cabernet Sauvignon (a cross of Sauvignon Blanc and Cabernet Franc)

in a laboratory:

• Müller-Thurgau (a cross between Riesling and Madeleine Royale).

Question 76

What do scientist aim for when creating new varieties?

Answer 76

The aim is usually to create an offspring that has the favourable characteristics of the two parent vines, but in reality this often does not happen.

For example, Müller-Thurgau, a cross between Riesling and Madeleine Royale, was created to have the fruit quality of Riesling and the high yield of Madeleine Royale. However, while it has proved to be a variety valuable for its yields, very few would claim it has the same quality potential as Riesling.

Question 77

Why do new grape varieties rarely come to market?

Answer 77

The main reason is consumer resistance.