Topic 3 - Grapevine Structure

Question 1

What are the permanent parts of the grapevine?

Answer 1

• Roots
• Trunk
• Cordons/ arms

Question 2

What are the annual parts of the grapevine?

Answer 2

• Shoots
• Leaves
• Tendrils
• Fruit

Question 3

Describe the root system?

Answer 3

The root system is a branched structure containing:

• A main framework called the structural roots (permanent).
• Lateral roots (permanent). Permanent lateral roots, arising from the structural roots that grow horizontally (called spreaders) or downwards (called sinkers).
• Branching off the permanent lateral roots produces the smaller fibrous lateral roots, called feeder roots.

Question 4

What does the root tip include? What is a root cap?

Answer 4

The root tip is 2-4 mm long and includes the apical meristem.

A root cap is found on the end of the root tip, the root cap protects the root apex as the root pushes through the soil. This cap is continuously worn away and replaced by cell division in the root tip.

Question 5

What are factors that influence how deep the roots of a grapevine grow?

Answer 5

• Soil, water, variety, rootstock, and cultivation,
• Irrigation: if you drip irrigate your vines, the roots will concentrate under the drippers, whereas if you rely on rainfall, they will grow deeper
• Shallow, waterlogged, or compacted soils can impede root growth, while soil nutrient deficiencies or imbalances could also inhibit root growth

Question 6

What the functions of grapevine roots?

Answer 6

1. Anchor the vine securely into the soil.
2. Absorb water and nutrients from the soil
3. Store reserves (stores carbohydrates and nutrients which are essential for early spring growth)
4. Produce hormones that regulate vine growth

Question 7

What is the difference between cordon training (spurs) and head training?

Answer 7

– If the arms are long, which is usually the preferred training method, they are called cordons / cordon-trained
– If the arms are short, it is called head-training
– Cordons can extend from the trunk in either one or two directions called unilateral or bilateral.

Question 8

What are the functions of the trunk and cordons?

Answer 8

• Raise the vine off the ground, provide support/structure for other parts of the vine
• Translocation of water, carbohydrates and nutrients between roots and shoots – within these structures vines have vascular tissues
• Store reserves – similar to the roots they store carbohydrates and nutrients

Question 9

What are buds?

Answer 9

– Buds are compressed shoots formed in the axil of leaves at each node

Question 10

Describe the structure of a bud?

Answer 10

The structure of buds is complex and contains:

– A part that grows immediately called a prompt bud / basal bud which develops into a summer lateral shoot
– Other parts that remain compressed until the next season known as a latent/ compound bud. Latent buds grow into shoots in spring the next season.
– Therefore at each node position on a main shoot there is a prompt bud (forming a lateral shoot in the current season) and a compound bud (only bursts the following season).
– The compound bud contains three buds, one primary bud and two secondary buds. The primary bud usually bursts before the secondary buds, which do not always burst.

Question 11

What are the functions of buds?

Answer 11

• All the buds within the compound bud have the potential to develop into new shoots the following spring.
• The principal function of the buds is to ensure reproduction (i.e. to ensure fruitfulness for the next season).

Question 12

What are non-count buds?

Answer 12

The base buds on each shoot are known as ‘non-count buds’ and have indistinct internode/shoot tissue between the bud and the spur or cane (other buds, i.e., count buds, have distinct internode tissue between the bud and an adjacent bud).

These non-count buds usually won’t burst and are often not fruitful, if they do burst.

Question 13

What are shoots?

Answer 13

Shoots are green stems that develop from the primary buds.

Shoots are the primary growth structure of grapevines, carrying leaves, tendrils, inflorescences that will mature into bunches, and new buds arranged in regular patterns along the shoot.

Question 14

What are nodes?

Answer 14

• Nodes are slightly enlarged areas on the shoot.
• Each node hosts a leaf, a compound bud (which overwinters), a lateral shoot (emerging from the prompt bud), and either an inflorescence (which becomes a bunch during the fruit set period) or a tendril, or ‘miss’ (‘miss’ refers to neither a tendril nor an inflorescence being present)

Question 15

What is internode?

Answer 15

• Internode is the area of shoot tissue between two adjacent nodes.
• Internode lengths vary between varieties, species, shoot vigour and shoot orientation. The internode length can be assessed to roughly evaluate the rate of shoot growth during the season.

Question 16

What happens to shoots late in the season?

Answer 16

• Shoots lignify late in the season are referred to as ‘canes’.
• Canes become dormant from leaf gall through to its second season. When the vine is pruned, dormant canes are cut back to either spurs or canes.

Question 17

What happens when the main shoot’s tip (apical meristem) is removed?

Answer 17

• Lateral shoot development is very strongly stimulated when the main shoot’s tip is removed, this regularly occurs when the main shoots are being trimmed during the growing season as part of a canopy management protocol, usually in an attempt to control vine vigour.

Question 18

Describe the shoot functions.

Answer 18

– Carry the buds, leaves, tendrils and fruit – therefore essential for vine growth
– Transport of carbohydrates, nutrients and water
– Canes also store reserves
– The shoot tip apical meristem has two functions: the production of new organs and the production of new tissue.

Question 19

What are the two main structures of grapevine leaves?

Answer 19

Lamina (blade) and petiole (stalk)

Question 20

What is the shape of the grapevine leaf lamina dependent on?

Answer 20

The shape of the laminas are very dependent of the variety, and most varieties have five-lobbed laminas.

Question 21

Describe the upper epidermis (on the top) and lower epidermis (on the bottom) of the lamina

Answer 21

The upper epidermis (on the top) of the lamina contains almost no stomata and is covered in a layer of wax.

Chloroplasts are abundant in the leaf mesophyll, located inside the lamina.

The lower epidermis (on the bottom) has many stomata which provide the pathway for the diffusion of water vapour out of the leaf (transpiration) and CO2 into the leaf (gas exchange).

Question 22

Describe the functions of the leaves and petioles

Answer 22

• The main roles of leaves are photosynthesis and transpiration.
• The carbohydrates produced during photosynthesis are used for growth and metabolism throughout the vine.
• Transpiration of water via the stomata acts as a cooling mechanism, protecting the leaf from heat. Transpiration also drives the transport system of nutrients through the xylem from the roots.
• The vascular tissues in the petioles are the pathway for carbohydrates and many nutrients from the leaves to the rest of the vine.

Question 23

What are tendrils?

Answer 23

• Tendrils are long, winding protrusions which coil and wind around fences, trellises, the plant itself and anything they may reach
• Tendrils are structurally homologous inflorescences, and therefore, tendrils are essentially modified inflorescences.
• Found in a pattern along shoot, never on same node as inflorescence

Question 24

What pattern are tendrils found along a shoot?

Answer 24

• Tendril, tendril, miss, tendril, tendril, miss (every third node thus lacks a tendril).
• Not found on same node as an inflorescence. Inflorescences occupy the basal two or more tendril positions on fruitful shoots in Vitis vinifera.

Question 25

What are the functions of grapevine tendrils?

Answer 25

• Essential for the climbing habit of the vine.
• Attach vines to trellis wires in vineyards and help support the vine and hold the shoots upright, therefore contributing to leaf sunlight exposure.

Question 26

What are the reproductive structures of grapevines?

Answer 26

1. Inflorescences
2. Flowers
3. Bunches and berries

Question 26

What are the reproductive structures of grapevines?

Answer 26

1. Inflorescences
2. Flowers
3. Bunches and berries

Question 27

What are inflorescences?

Answer 27

• What eventually develops into a bunch when flowers become berries.
• Starts off as a primordium within the compound bud, which is formed the season prior to the season when the inflorescence emerges on a shoot.
• The inflorescence contains flowers which are transformed into berries during the fruit set period.
• The inflorescence arises opposite a leaf in the same position as a tendril (tendrils and inflorescences never appear on the same node).

Question 28

What is usually the fruit zone (bunch zone)?

How many inflorescences will a fruitful shoot usually contain?

Answer 28

1. An inflorescence is most commonly found on the 4th and 5th nodes from the base of a shoot; this is known as the fruiting zone (or bunch zone).
2. Usually contains 1 to 3 inflorescences.

Question 29

Describe the main features of Vitis vinifera flowers

Answer 29

• monoecious (each plant has male and female flowers)

- hermaphroditic flowers (functional stamens, the male part, and pistils, the female part, present on the same flower)

Question 30

What is anthesis? What happens in this period?

Answer 30

• Grapevines go through flowering during spring; this period is also known as anthesis.
• During flowering, the flower caps fall, and pollination then occurs when pollen grains land on the stigma to induce fertilisation.
• After fertilisation, a flower develops into a berry during a process called fruit set.

Question 31

When does a bunch develop?

Answer 31

• The bunch is a fertilised inflorescence, and a berry develops from a pollinated flower.
• Some or all flowers on an inflorescence usually go through pollination for a bunch to develop.

Question 32

What factors influence bunch size?

Answer 32

• Vary widely between varieties

- Cultural practices, including pruning methods and irrigation

Question 33

What is the berry made up of?

Answer 33

• Seeds, flesh and skin.
• Outside of a berry is covered in a waxy coating, which can contribute to protecting the berry against pathogen infections and influences the wettability of the berry.

Question 34

What factors influence the size of a berry?

Answer 34

• Berry weight is largely dependent on variety, environment and cultural practices.
• Increased irrigation, for example, will result in larger berries.

Question 35

How does water flow into a berry?

Answer 35

• Vascular bundles (xylem and phloem) supply water and nutrients to the berry.
• Water flows into the berry via the xylem and phloem.

Question 36

What do the skin and flesh cells of berries contain?

Answer 36

• The skin and flesh cells contain vacuoles that host water and chemical compounds, including sugars (mostly glucose and fructose) and acids (mostly malic acid and tartaric acid).

Question 37

What organic acids are found in berries?

What sugars are found in berries?

Answer 37

1) Mostly malic and tartaric acid

2) Mostly glucose and fructose

Question 38

What do the skins of berries contain?

Answer 38

• Skins contain coloured pigments, including anthocyanins which are the red pigments found in the skins of red varieties from after veraison (when berry ripening initiates).

Question 39

How do grape berry seeds form?

How many seeds does each berry normally contain?

What happens to the seed when it matures?

Answer 39

1) Develop from the fertilised ovules (the ovules are contained inside the ovary of the flowers).
2) Up to four seeds, however, mainly two or three.
3) Outside hardens and lignifies, the colour then changes from green to brown. This colour change is one of the indications that the berries are reaching maturity. The seeds are already brown when the berries are optimally ripe for harvesting.

Question 40

What are the functions of the fruit?

Answer 40

• The seeds ensure the survival of the vine. When a berry falls onto the ground or is dropped on the ground by birds or mammals, the seeds are released and lie on the soil surface.
• Under favourable conditions, a seed can germinate and form a new vine.
• The berry is a source of food for animals and humans, while a man-made function of berries is that of wine production.

Question 41

Which of the following best describes lateral shoots?

a) They are generally unfruitful and arise from latent buds.
b) They bear the majority of the primary crop.
c) They are also called water shoots and arise from adventitious buds.
d) They form the vine’s permanent structures (arms) once they lignify.
e) They are generally unfruitful and arise from prompt buds.

Question 42

Four of the following statements are INCORRECT. Which one is the correct statement?

a) the prompt bud is a compound bud consisting of three buds
b) grapevine leaves carry out respiration
c) Chardonnay grapes grown under warm climatic conditions have more anthocyanins in their skins than most other Vitis vinifera varieties
d) Phase 2, or the lag phase of berry development, is most obvious in grape berries that lack seeds
e) Grapevines are woody annual plants tolerant of stress

Answer 42

b) grapevine leaves carry out respiration

Question 43

The principal organic acids found in the grape berry are:

a) Sulphuric acid and malic acid.
b) Malic acid and acetic acid.
c) Tartaric acid and malic acid.
d) Tartaric acid and nitric acid.
e) Citric acid and tartaric acid.

Answer 43

c) Tartaric acid and malic acid.

Question 44

With respect to berries, the mesocarp is?

a) The skin and flesh
b) Where the seeds are encased
c) The waxy coating on the outside of the skin
d) The flesh
e) The ovary wall

Answer 44

d) The flesh

Question 45

What developments happen to the ovary wall of the flower after flowering?

Answer 45

• After flowering, the ovary wall of the flower develops into the pericarp of the berry, which is comprised of the exocarp (the skin) and the mesocarp (the flesh).

Question 46

Nodes on a grapevine shoot have the role of?

a) Keeping the shoot straight
b) Containing leaf primordia
c) Containing seeds
d) Containing an apical meristem
e) A method of measuring shoot length

Answer 46

b) Containing leaf primordia

Question 47

In grape berries, the most common carbohydrates are?

a) Starch and pectins
b) Maltose and fructose
c) Glucose and fructose
d) Glucose and sucrose
e) Fructose and sucrose

Answer 47

c) Glucose and fructose

Question 48

Grapevine roots have several functions that maintain grapevine survival. What are they?

Answer 48

1. Anchor the vine securely into the soil.
2. Absorb water and nutrients from the soil
3. Store reserves (stores carbohydrates and nutrients which are essential for early spring growth)
4. Produce hormones that regulate vine growth

Question 49

Although the lateral shoot is not usually fruitful, it has a significant role in grapevine reproduction. What is this role?

Question 50

Define a latent bud and describe what such a bud may contain.

Answer 50

The ‘latent’ buds is a bud that remains dormant until the following spring. The latent bud is made up of a primary and two secondary buds and are collectively known as the ‘compound bud’.

Question 51

What is unusual about the pattern of tendrils growing along a grapevine shoot?

Question 52

Consider the following statements:

i) Prompt buds are latent compound buds that are not fruitful
ii) A ‘non-count’ bud is found near the base of a spur and is where lateral shoots emerge from

A. Both statements are true
B. Both statements are false
C. Statement i) is true and statement ii) is false
D. Statement i) false and statement ii) is true

Answer 52

B. Both statements are false

Question 53

Which grapevine organ is the main source of carbohydrates shortly after budburst?

A. Leaves
B. The compound buds
C. Roots
D. Young shoots

Answer 53

C. Roots

Question 54

Consider the following statements:

i. A grapevine flower develops into a seed at fruit set
ii. A grapevine inflorescence develops into a berry at fruit set

A. Statement i) is correct, but statement ii) is incorrect
B. Statement i) is incorrect, but statement ii) is correct
C. Both statements are incorrect
D. Both statements are correct

Answer 54

C. Both statements are incorrect

Question 55

Which of the following will not be expected to inhibit inflorescence initiation in the compound bud?

A. Intense sunlight exposure
B. Nitrogen deficiency
C. Oversupply of nitrogen
D. Cold temperatures after budburst

Answer 55

A. Intense sunlight exposure

Exposure of the new buds on young shoots to sunlight increases fruitfulness (stimulates the formation of an inflorescence primordium instead of a tendril primordium).