The Vine

Question 1

Name the most important American vine species and the most important Eurasian vine species?

Answer 1

North American: Vitis Labrusca, Vitis Riparia, Vitis Berlandieri, Vitis Rupestris, Eurasia: Vitis vinifera

Question 2

Explain the anatomy of the vine?

Answer 2

Structure can be divided into four sections: the shoots, the one-year-old wood, permanent wood and the roots.

Question 3

What is the structure of the shoots?

Answer 3

The structure of the shoots are the buds, leaves, tendrils, lateral shoots and inflorescences or grape bunches.

Question 4

What are solutes?

Answer 4

Solutes are substances that dissolve in a liquid, to form a solution and in this instance include sugars and minerals.

Question 5

Explain the stem of the shoot?

Answer 5

It transports water and solutes to and from the different structures. The stem is also a store of carbohydrates. The little swellings along the stem, where the other structures are attached, are called nodes. The lengths of stem in between the nodes are called internodes.

Question 6

What are buds and what type of buds are there?

Answer 6

Buds form between the leaf stalk (petiole) and the stem. There are two main types of buds: 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). They produce the main shoots in the next growing season. Within a compound bud, there is typically a primary bud (the main growing point) and smaller secondary and tertiary buds. The secondary and tertiary buds usually only grow if damage has occurred to the primary bud (e.g. spring frost). Prompt buds form and break open in the same growing season. They form on the main shoot (that has just grown from a compound bud) and produce lateral shoots.

Question 7

What are lateral shoots?

Answer 7

Lateral shoots grow from buds formed in the current year (prompt buds). They are smaller and thinner than the main shoots. Lateral shoots have a stem, leaves, buds, tendrils and sometimes inflorescences. Lateral shoots can provide an additional source of leaves for photosynthesis. Lateral shoots often produce inflorescences, which can be known as a ‘second crop’. However, this can depend on the grape variety and canopy management techniques. Pinot Noir is a grape variety that often forms inflorescences on lateral shoots.

Question 8

What is photosynthesis?

Answer 8

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

Question 9

What are the tendrils of vines?

Answer 9

The shoot cannot support itself, therefore vines have tendrils. In the wild, these tendrils would have been used to attach the vine to other plants or trees, providing support. 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. However, grape growers typically do not trust the tendrils to hold the vine to the trellis on their own and therefore they tie in canes and shoots as necessary.

Question 10

Explain the leaves of vines?

Answer 10

The leaves are the main site of photosynthesis in the vine. The sugars produced in photosynthesis are used for vine growth and metabolism. Stomata (pores) open on the underside of the leaves, letting water diffuse out and carbon dioxide for photosynthesis to enter. As water diffuses from the leaf, a process called transpiration draws water and nutrients from the soil up through the vine to the leaves. These 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 11

What are inflorescences?

Answer 11

The inflorescence is a cluster of flowers on a stem, which becomes a bunch of grapes at fruit set. The number of inflorescences on each main shoot can depend on the grape variety, but is usually between one and three.

Question 12

What are the bunches?

Answer 12

A bunch of grapes is a fertilised inflorescence. Usually, not all the flowers in the inflorescence will successfully become grapes.

Question 13

Explain what grapes are?

Answer 13

A grape is a type of berry. In broad terms, a grape is made up of pulp, skin and seeds. Pulp – The pulp makes up the majority of the grape’s weight and volume. It contains water, sugars, acids and some aroma compounds and aroma precursors. The pulp of most grapes is colourless. Skin – The skin of the grape contains a high concentration of aroma compounds and aroma precursors, tannins and colour compounds. Seeds – Seeds mature inside the grape, turning yellow to dark brown. Seeds contain oils, tannins and the embryo, which can grow into a new plant. A powdery waxy coating, called the bloom, covers the surface of the grape.

Question 14

What is one-year-old wood?

Answer 14

One-year-old wood refers to the main shoots from the last growing season that were kept at pruning. The amount of one-year-old wood will depend on the pruning and training decisions made by the grape grower. Importantly, the one-year-old wood supports the compound buds that will break to release the main shoots for the upcoming growing season. Depending on how the vine is pruned the one-year-old wood will either be called a cane or a spur.

Question 15

What is permanent wood?

Answer 15

These are the woody parts of the vine that are older than one year, including the trunk. Depending on pruning and training decisions, some vines also have one or more horizontal arms of permanent wood, often called cordons. The trunk and cordons provide support for the other parts of the vine. They transport water and solutes to and from different parts of the vine and store carbohydrates and nutrients.

Question 16

Explain the roots?

Answer 16

The roots are important for anchoring the vine and also for the uptake of water and nutrients. The roots are also a store of carbohydrates and produce hormones that have important functions within vine growth and grape ripening. 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. Distribution of the main framework of roots is influenced by the soil properties, irrigation, cultivation and the type of rootstock. The water and nutrients are absorbed at the root tips, where the roots are actively growing.

Question 17

What are cuttings with vine propagation?

Answer 17

A cutting is a section of a vine shoot that is planted and then grows as a new plant. This is by far the most common propagation technique as many small cuttings can be taken from a vine and propagated at the same time. It also permits the use of rootstocks, which can easily be grafted onto the vine cutting before it is planted. In addition, nurseries are able to treat vine cuttings to avoid spread of diseases.

Question 18

What is layering with vine propagation?

Answer 18

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. 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 and, once these roots are established, the cane linking the new growth to the original plant is cut. The new vine grows on its own roots, not those of a rootstock, and this method is therefore not always suitable. The new vine will have no protection against phylloxera or have the qualities (such as the desired yield) that a choice of rootstocks offers (for more details see Planting Materials). Importantly, in viticulture, vines are not propagated through seeds. 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 19

What are clones?

Answer 19

The methods of cutting and layering usually produce vines that are genetically identical to the parent vine. However, at each cell division during plant growth there is the risk that random mutations in the genetic code will occur. 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.). This causes diversity within the vines of the same grape variety. Vines with particularly favourable characteristics are selected by vine nurseries or grape growers for propagation by cuttings in order to grow new vines with these favourable characteristics. This is known as clonal selection, with each of the slightly different vines known as clones. 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 20

Give an example of Pinot Noir clones for high quality red wine production and one for sparkling wine?

Answer 20

Pinot Noir Clone 115 has low yields of small grapes, making it suited to high quality red wine production. By comparison, Pinot Noir Clone 521 has higher yields of bigger grapes, making it better suited to sparkling wine production. This is because high concentrations of tannins and colour from the skins are not needed in these wines.

Question 21

Explain the benefit of buying young vines from a nursery?

Answer 21

One of the reasons for this is that young vines purchased from nurseries have been tested to be free from virus infection. However, depending on the region and the grape variety, only a very limited number of clones may be available from nurseries, and in some cases these clones may have been chosen for maximising yields rather than fruit quality. This means that the vines planted across a vineyard or even a region can be relatively uniform, especially if natural factors are consistent across the region. This may have some benefits: if all of the vines grow in a similar way and ripen grapes at the same time as each other, management of the vineyard becomes simpler. However, it can also be disadvantageous, meaning there is less diversity in the fruit and hence potentially producing a wine with less complexity and balance (if that is desired for the style and quality of the wine) It also makes the vineyard more susceptible to disease (the identical vines are likely to all be equally susceptible to a disease or pest). For these reasons, where available, a grape grower will often buy and plant a number of different clones of the same grape variety.

Question 22

What is Selection Massale?

Answer 22

Also referred to as mass selection is a technique regaining popularity with some vineyard owners. The technique requires vineyard owners to take cuttings from the vines in their own vineyard(s) and cultivate these cuttings. (The cuttings can be sent to a nursery for grafting onto rootstock where necessary.) 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. An advantage of mass selection is that it increases the diversity of planting material in the vineyard and throughout the region. Another advantage is that the vineyard owner is using their own unique planting material (different from that being bought from the local nursery), which can enhance fruit quality and/or yield (and can be used as a marketing asset). However, the selection and monitoring of vines to ensure the propagation of the best vines is costly in terms of time and labour. Further, if the parent vine is infected by disease (e.g. a virus), this is likely to be passed onto the new vines, and therefore this technique can increase the spread of vine diseases.

Question 23

Explain how new grape varieties occur?

Answer 23

New grape varieties are typically produced from seeds. 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; this is called cross fertilisation. Grapes develop and the seeds from these plants are planted and grown. The new vines that grow from the seeds will all have different characteristics (in the way that siblings in a family are not identical to each other or their parents). If one of the new vines has desirable characteristics, it may be propagated by cuttings to create identical vines. The potential and long-term value of the new vine will be assessed over a long period of time. If there is thought to be value in making this new variety available commercially, it will need to be registered on the OIV catalogue as a new grape variety.

Question 24

What is a cross?

Answer 24

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

Question 25

What is a hybrid?

Answer 25

When the two parent vines are from different species, the offspring is called a ‘hybrid’. Possibly the best-known hybrid for wine production is Vidal Blanc, from Ugni Blanc (V. vinifera) and a member of the Seibel family (American parentage). Hybrids in particular were bred in an attempt to combine the resistance of non-vinifera species (to diseases, pests or climatic extremes) and the quality of fruit from V. vinifera. Unfortunately, many hybrids do not produce fruit that matches the quality of most V. vinifera (although there are notable exceptions), but their other characteristics make them useful as rootstocks.