Viticulture Flashcards
Define PHOTOSYNTHESIS
The process by which green plants use sunlight to produce sugars from CO2 and H2O
The leaves are the main site of photosynthesis in the vine
Sugars produced in photosynthesis are used for vine growth and metabolism
Describe TRANSPIRATION
Evaporation of water from tissue inside the leaf-
Pulls water up through roots and transport nutrients
Water vapour diffuses our of stomata on the underside of the vine leaves
Loss of water in leaf causes water to be pulled upward through soil, through roots and above-ground parts of the vine
Why does the vine need sunlight?
For photosynthesis- process by which green plants use sunlight to produce sugars from co2 and h2o
Why does the vine need HEAT?
Certain amount needed for photosynthesis and transpiration.
Heat is a good mechanism to tell vine when to start growing (leaves etc) (10deg vine starts to wake up)
Methoxypyrazines broken down by heat and light
what is the effect of heat and sunlight on tannin
Tannin creation happens from heat and sunlight when grapes are green.
During veraison causes them to polymerise - go from short chain tannins to long chain tannins = become softer
Why is water a requirement for the vine
Needed for photosynthesis
Transporting things around plant
To build up the grapes
Water needed for structure- otherwise the vine will wilt
Where does the majority of the root action happen?
In the first 1-2 metres
What would be the reason for a vine having a large root system, and how might that have benefited the vine?
A large root system means the roots have gone looking for nutrients/food.
Best fruit is produced when the vine/roots are under light stress
What is the reason for winter pruning ? (Late in season)
Protects from early budding. If you damage the vine later in season (Feb/early March) it has to heal and therefore buds a little later
What can happen to buds when there’s a clear night and clear sunny morning?
Can get scorched
How can sprinklers protect buds?
Create ice, exothermic reaction produces heat. Protects the bud (like an armour)
What are the ideal/“perfect” temps for flowering and pollination?
Flowering = 17deg Pollination = 26deg
What does the pollen tube require as it forms?
Warmth, doesn’t like damp
What do adverse temps at flowering and pollination mean for the vine ?
Mixture/uneven flowering and grape set
What are the extremely important weeks for ripening?
Last 6-8 weeks
What effect does too much nitrogen/soil condition too favourable have on fruit set?
Delays fruit set.
Stressing the vine at the start of the season can help
What happens, with regard to sugars and acids, during veraison?
Sugar starts to go into grape
Vine lives of Malic acid at this stage- uses for energy
(The plant changes its food source)
I.e. sugar levels go up = Malic acid goes down
What effect do warm and dry conditions have on the vine during grape formation?
Higher rate of transpiration = more sugar pulled up into the grape
Warmer climate = higher sugar/ higher level of alcohol = Malic acid lower
Describe continental climate classification
Away from large bodies of water
Dry
More extreme differences between summer and winter temsps
Short, sharp summers
Temps rapidly changing in spring and autumn
E.g. - Burgundy and Alsace
Describe maritime classification
Volatile environment
Relatively humid
Not particularly warm
Start of spring and harvest temps not optimal
Rainfall spread evenly through the year
Low annual differences between summer and winter temps.
Describe Mediterranean classification
Like maritime, but warmer
Low annual differences between summer and winter temps
By body of water
Warm/dry summers
Extended autumn
Sea adds warmth
Annual rainfall tends to fall in the winter months
E.g. Napa valley and Coonawarra
What does GDD stand for and what does it mean?
Growing degree days
E.g. how many days in month are we above 10deg?
What are MJT and GST?
Mean temps in warmest month
Growing season temperature
What is the degree change for every 100m up in altitude?
0.6deg
What are the 5 main nutrients required by the vine, and what for
NITROGEN- for green growth. Legumes can be planted to pull nitrogen into the soil
POTASSIUM - helps water to be taken up - helps with root system
PHOSPHOROUS - required for photosynthesis
CALCIUM - needed in small amount, too much = chlorosis = yellowing of leaves
MAGNESIUM - chlorophyll = needed for green parts
What are the 5 main requirements of the vine
SUNLIGHT WARMTH CARBON DIOXIDE WATER NUTRIENTS
How can a grower influence how the vines requirements are met? (4)
CANOPY MANAGEMENT
SOIL MANAGEMENT
WATER MANAGEMENT
HAZARD MANAGEMENT
What are the key aims of canopy management? (6)
Maximise effectiveness of light interception
Reduce shade within canopy
Ensure microclimate is as uniform as poss- even ripening
Promote balance between vegetative and reproductive functions of vine
Arrange vine canopy for mechanism
Air circulation through canopy to reduce incidence of disease
What is the risk of clay and limestone soil (e.g. Chablis)
Not a lot of nitrogen- if you don’t add to the must, yeasts can struggle, give off sulphur compounds
What is the name given to grape varieties that require relatively low temps at budburst and give 4 examples
Early budding
Chardonnay, Pinot Noir, Grenache, Merlot
What is the name given to grape varieties that require higher temps at budburst and give 3 examples
Late budding
Cabernet sauvignon
Sauvignon Blanc
Syrah