Physiology and Life Cycle of the Vine Flashcards
How is a vine’s morphology commonly divided?
Vegetative parts
Reproductive parts
What are the only below-ground parts of the vine?
The roots
What is the vine canopy?
The entire above ground part of the vine
What three functions do roots perform for the vine?
Anchor the vine
Absorb water and nutrients
Store carbohydrate reserves for winter growth and shoot/leaf creation in the spring
How deep do structural roots penetrate into soil?
Usually 30-35cm, though depths of 6m have been recorded
What is the diameter of structural roots?
6-10mm
Where do narrow root branches tend to be found?
The upper 20-50cm of soil
Where are most roots found?
Within a 4-8m horizontal diameter of the vine
How do roots absorb water and nutrients?
Through the root’s absorption zone, a 100mm long area just behind the root tip covered in fine root hairs.
The hairs dramatically increase the surface area of the root
Where are the most actively absorptive roots found in the soil?
The upper 10-60cm
Why is it important for roots to store carbohydrates for the vine during winter and early spring?
There are no leaves to photosynthesize, therefore no sugar and starch production
What are the permanent above ground structures of the vine?
The trunk and arms
What is the trunk?
The permanent, vertical wood that extends out of the ground.
It transports water and nutrients from the roots to the leaves and fruits through the arms.
What are the arms?
Permanent wood growing out of the trunk from which the shoots grow.
It transports water and nutrients from the roots and trunk to the leaves and fruits.
What types of arms might be trained in a vine?
Cordons
Long, horizontal arms
Spurs
Short, angled between horizontal and vertical
How much of the vine’s dry matter is permanent wood?
Why is this important?
50-75%
The permanent wood stores carbohydrates and mineral nutrients, buffering the vine against unfavorable conditions during the growing season and winter months.
Grapevines are climbing plants. What does this mean for cultivation?
In their natural state, vines rely on external rigid frames such as trees to spread their canopy.
Trellising is generally needed in vineyards to support longer permanent arms and annual growth shoots unless the vines are very close to the ground
What is a node?
A segment of the vine characterized by a swelling in the vine’s growing area (shoot) that are regularly spaced and contain the beginnings of leaves, lateral shoots, tendrils, and inflorescences.
What is a bud?
A growing point in the vine from which the shoots grow from the vine. They form at the base of the leaf stalks.
What is an internode?
The space between nodes on a shoot, generally 5-15cm long depending on cultivar and vigor.
What is a dormant bud?
These do not develop further in the growing season. They become dormant over the winter until bud break the following season.
Climate in the first season thus affects growth and fertility in the second season.
Also called a latent bud.
What is a prompt bud?
A bud that breaks in the same year it is formed.
What is a shoot?
A structure that grows from the vine out of buds. It continues to grow throughout the season, developing nodes and internodes that support the vine’s leaves, tendrils, and inflorescences.
Shoots also develop their own buds, some of which shoot during the season and others which remain dormant until the following season.
What is a tendril?
A part of the vine that grows out of some nodes to support the vine by coiling around trees (or trellis wires). They ensure shoots are in a position that maximizes leaf exposure to sunlight for optimal photosynthesis.
What is a cane?
A maturation of the shoot into a woody stem at the end of the growing season.
What is a leaf?
The main organ of photosynthesis. Vine leaves are generally five-lobed and exchange gas byproducts through stomata (pores) on the underside of of the leaf.
What is the annual growth cycle of the vine?
Budburst and Shoot Growth
Inflorescence Initiation
Flowering (Bloom/Reproduction Cycle)
Fruit Set
Berry Development
Harvest
Wood Ripening, Leaf Fall, and Dormancy
What physiological response signifies the beginning of the vine’s growth cycle?
A rising of sap just before budbreak
What two cycles define the vine’s growing season?
Vegetative
Reproductive
What is an inflorescence?
The fruiting structure of the vine, containing the flowers that will become berries following fertilization.
True or False
Most V. vinifera vines are hermaphroditic.
True
Vines can self-fertilize because they have male and female reproductive organs on the same inflorescence.
What role do berries fulfill in the wild?
They are the vine’s natural means of reproduction and survival. They attract animals to eat the seeds and spread them to new environments.
What is the difference between a grape berry and a grape bunch?
A berry is a fertilized flower.
A bunch is a fertilized inflorescence.
If flowering occurs in cold or wet weather, why might berries of the same bunch ripen at different times?
Uneven fertilization of an inflorescence
When is the active growing cycle in the Northern Hemisphere?
March/April to October/November
When is the active growing cycle in the Southern Hemisphere?
September/October to April/May
When does budburst and shoot growth occur in the Northern Hemisphere?
March and April
When does budburst and shoot growth occur in the Southern Hemisphere?
September and October
When does flowering and fruit set occur in the Northern Hemisphere?
May and June
When does flowering and fruit set occur in the Southern Hemisphere?
November and December
When does berry growth, veraison, and berry ripening take place in the Northern Hemisphere?
July and August
When does berry growth, veraison, and berry ripening take place in the Southern Hemisphere?
January and February
When does harvest take place in the Northern Hemisphere?
August, September, and October
When does harvest take place in the Southern Hemisphere?
February, March, and April
What is the vine’s dormancy period in the Northern Hemisphere?
October through February
What is the vine’s dormancy period in the Southern Hemisphere?
April through August
How does cultivar variation affect the timing of annual vine growth?
Vines generally follow the same annual growth pattern, but the specifics of some cultivars (early budding, ripening time, etc.) affect the ability to plant cultivars in certain climates.
What is the impetus for budburst?
The mean daily temperature exceeds 10°C
What happens during budburst?
Carbohydrates stored in the roots during the winter begin to move into the vine’s trunk and arms as sap to provide nutrients. These stored carbohydrates are used to fuel early shoot and leaf growth.
The leaves eventually become plentiful enough to fuel the vine’s processes exclusively. Shoot and leaf growth is rapid until flowering.
What phenomena drives budding in late-budding cultivars?
Temperature. Late budding cultivars need higher temperatures.
How long after budburst does inflorescence begin?
About eight weeks
Why is fine weather important during flowering and fruit set?
Too much rain or wind can wash or blow away the pollen, resulting in low fruit set and a small crop
How does unfavorable weather during inflorescence initiation affect the vine?
It harms the crop in that year and the following year
When and where does inflorescence initiation begin?
Around the same time as flowering
Inside the bud
How long does flowering take to complete?
7-10 days
What are the ideal conditions for flowering?
Sunny, dry days with a temperature between 26°C and 32°C
Dry conditions are most favorable for the release of pollen into the air and their transfer to the stigma for pollination
How do rain and wind affect pollination?
They make it difficult for pollen to reach the stigma
Describe the germination process.
Pollen lands and rests on the stigma, producing a pollen tube that reaches into the ovule to the egg within. Fertilization of the egg leads to fruit set.
What temperatures slow down and potentially prevents germination?
15°C and below
What is fruit set?
The end of flowering, when the ovary of a fertilized flower forms a berry
What conditions are necessary for positive fruit set?
Sunlight and warm temperatures
What conditions are hazardous for fruit set?
Cloudy, wet, and cold weather
Even excessive shading can reduce fruitfulness
What is Coulure?
Poor fruit set
Poor light results in many unfertilized berries and small young berries that fall off. Bunches are loose and sparsely populated.
What is Millerandage?
“Hens and Chickens”
Low temperature results in a mix of small, seedless berries that still ripen normally and larger, seeded berries on the same bunch.
When do berries begin to grow in the Northern Hemisphere?
June/July
Summer
When do berries begin to grow in the Southern Hemisphere?
December/January
Summer
When does Véraison begin in the Northern Hemisphere?
July/August
Late Summer
When does Véraison begin in the Southern Hemisphere?
January/February
Late Summer
When does Berry Ripening begin in the Northern Hemisphere?
August/September
Summer/Autumn
When does Berry Ripening begin in the Southern Hemisphere?
January/February
Summer/Autumn
What are the three (sometimes four) stages of berry development?
1) Berry Formation
2) Lag or Transition
3) Berry Ripening
4) Berry Over-Ripening
What occurs during Stage 1 of Berry Development?
Berry Formation
The growth and cell division of seeds and hard green berries. They increase in size over 6-8 weeks.
What occurs during Stage 2 of Berry Development?
Lag or Transition Phase
The growth of Stage 1 slows down. This lasts between 1 and 6 weeks, depending on the cultivar.
What occurs during stage 3 of Berry Development?
Berry Ripening
This phase starts with Véraison, the changing of the grape’s skin color. The seeds mature. Berry cells continue to enlarge, mature, and then soften.
Sugar, anthocyanins (in black cultivars), flavor and aroma compounds accumulate while acid levels reduce.
This stage lasts 5-8 weeks.
What occurs during Stage 4 of Berry Development?
Berry Over-Ripening
Occurs when harvest is delayed accidentally or deliberately. The berries begin to shrivel on the vine.
The sugar levels in shrivelled grapes and those affected by noble rot may be more than double those of healthy, ripe grapes.
What happens to vine shoots at the end of autumn?
They mature, harden, and turn brown. At this point they become Canes.
What happens to the vine as the temperature drops?
Leaves fall off and the buds due to burst in spring become dormant.
Carbohydrate reserves are put into the permanent parts of the vine.
Why is cold temperature important to viticulture?
A period of cold temperature, ideally in late winter, is required to start reactivating dormant buds ready for spring bursting.
Regions without sufficiently cold temperature during the dormant period may lead to irregular budburst in the spring.
How is the life cycle of vines grown in subtropical and tropical regions different from those in temperate regions?
There is no dormant period for vines in the subtropics and tropics. They are evergreen and may even produce multiple yields in a year.
What is the correlation between vine age and yield?
Inverse.
As a vine increases in size, growing more permanent wood, shoot vigor declines. More energy is required to keep the permanent wood healthy, so less energy is put into growing shoots and fruit.
How long after planting does it take a vine to yield a crop?
Two or three years.
Vines only grow vegetatively until the first flowers develop.
What effect does low yield and cultivation have on the average age of a vine?
Eventually the vine may yield so little fruit that keeping it would be cost ineffective. Replanting may be the ultimate solution to vine age if grape value does not support costs.
What is the average age of a vine that follows a normal replacement strategy?
25-30 years
What are the stages of a vine’s growth cycle?
Budburst
Shoot Growth
Flowering
Fruit set
Berry Growth
Veraison
Berry Ripening
Wood Ripening
Leaf Fall
