D1 - Viticulture Flashcards
Types of buds
Prompt Buds and Compound Bud
What is the internode?
The distance between two leaves. It determines the quantity of buds in a given length of cane (long internode = small crop)
What does it mean that vines are Lianas?
They do not produce extensive supporting structures.
In the wild they climb trees
Their shoots experience rapid vertical growth to compete for sunlight
What are Prompt buds?
also called lateral buds.
They develop into lateral during the current growing season
They are typically non-fruiting but may produce small clusters known as second crop
Explain compound buds
They spend the year maturing and develop into shoots in future years.
Compound buds are the most fruitful
They normally have a primary, a secondary and a tertiary bud
Other names for compound buds
Dormant or latent
What are the petioles?
The joint between a shoot and a leaf stalk
It is where buds are formed
What is the bloom of the grape?
The powdery waxy coating that covers the outside of the grape’s skin
What is the function of lateral shoots?
Allow the plant to grown if the tips of the primary shoots have been damaged.
Benefits and drawbacks of lateral buds
The one located near the top end of the primary ones, can benefit from sunlight and provide extra source of photosynthates.
If located neat the fruiting zone - too much shading on the bunches.
Characteristics of the second crop
They form on lateral shoots
They are not the norm, some varieties have more tendency to developing them - PN
The grapes ripen later
They are often removed with green harvesting
What is somata?
They are pores on the downside of the leaves that allow the exchange of gas and water with the atmosphere to allow photosynthesis to happen
What are the ideal conditions for photosynthesis to be at its highest rates?
Temperature: 18 - 33 C
Sunlight: 1/3 + of Full sunshine
What is an inflorescence?
a cluster of flowers on a stem, which becomes a bunch of grapes at fruit set
What is flowering?
The process in which individual flowers open up and expose the pollen-bearing stamens
How does fertilisation happen?
The pollen grains are shed and land on the moistened stigma surface, (pollination)
Here, they germinate, with each pollen grain producing a pollen tube. These pollen tubes penetrate the stigma and then the ovule in the ovary.
Where are flower clusters located?
at a node, opposite to a leaf
opposite to the first 1 or 2 leaves there will usually be no flower cluster. They will appear in the next 1-3 leaves, and will reduce in size as they move away from old wood.
Flowering cylce
Flowering process extends for two consecutive growing seasons. It is first induced in compound buds during summer, but initiation and floral development occurs in the following spring.
What are gubberellins?
Hormones that promotes shoot elongation, and therefore, delay of floral induction.
What are Cytokinins?
hormones produced by the root tips that promote bud break
What is the xylem ?
Part of the plant’s conduction system that transports water and solutes from the roots to the shoots
What is the phloem?
Part of the circulation system that conducts photosynthates and nutrients from the leaves to the rest of the plant. After véraison, all the water that the berries receive is transported through the Phloem.
Parts of the circulation system of the plant
Xylem and Phloem
What does it mean that the commercial vines are hermaphrodite?
That they are self-pollinating, their flowers are dotted with the male and female organs (pollen and ovary). They also do not depend on wind or insects to be pollinated, as the distance between the pollen stamens and the stigma is extremely small.
What are the factors that influence the root system size?
Type of rootstock, soil conditions and water supply
Factors that restrict root growth
- Shallow soils, especially those overlying an impervious rock or compacted soil
- water logged
- imbalanced soils
Functions of the roots
- anchor the plant in the soil
- conduct nutrients and moisture
- store reserves (CH)
- produce hormones
Consequences of a cold and wet spring
the root-hairs cant grow, leading to little hormone and sap production. Budburst is delayed, the ripening season will be shorter and the grape ripening may end in bad weather conditions.
what happens to the vine during dormancy?
- leaves fall
- green canes lignify
- buds seal against winter
- migration of CH ceases
Needs of the vine and adverse conditions during dormancy
- Needs: temperatures under 10°C
- Adverse conditions: Extremely low temperatures or unusual mild temperatures
What is Bud-burst?
The process in which buds swell and open. new shoots will then start to emerge.
vine’s needs and adverse conditions during bud-burst
- Needs: av. temperature in air and soil above 10°C, stored CH, sunlight, nutrients and water
- adverse conditions: Frost, cold soils, water stress, low CH levels
What temperature is required to the onset of bud break?
- Normally around 10°C
- this depends on the variety: early-budding ones will break at lower temperatures, while late-budding ones require higher temperatures.
What is bud-rubbing?
taking out buds at the beginning of the growing season. This is carried out where there is usually an excess of shoots, or where yields are restricted
What are the benefits of bud/shoot-rubbing?
- remaining shoots will grow in more open conditions
- reduction of shading
- higher light interception will increase bud fruitfulness in the following growing season
- reduction of fungal disease incidence
When is bud-rubbing normally practised?
in high-quality cordon-trained, spur-pruned vineyards and where there is usually an excess of shoots
When does shoot and leaf growth take place at its highest rate?
between budburst and flowering
How does CH reserves affect bud-burst?
- CH stores will sustain initial growth
- If CH levels are low, initial growth will be delayed and stunted.
Why may the CH reserve levels be too low at the beginning of the growing season?
It may be caused by excessive leaf removal or excessive high yields during the previous growing season.
ways of controlling weed on the vineyard floor
- cultivating using harrows
- grassed down and mown
- use herbicides
- Animal Grazing
- Plant cover crops
- mulching
- Synthetic Strips
When does flowering normally take place?
Within 8 week from budburst
Vine’s needs and adverse conditions during flowering
- Needs: Warm temperatures (+17°C), sunlight, water and nutrients
- adverse conditions: low temperatures, windy, cloudy or rainy conditions.
What is Coulure? Why is it caused?
- A condition in which vine experiences high proportion of failed pollination, therefore, poor fruit set.
- It is caused by CH imbalance during flowering. This may be caused by low photosynthesis rates (cold, cloudy cond. or extremely hot and dry), or over-vigorous shoot growth.
What is Millerandage? What are its causes?
- a condition in which there is a high proportion of seedless grapes. These are able to ripen, but will be smaller than normal berries. Therefore, yields will be smaller.
- Cause: cold, wet, windy weather during fruit set
What are the “suckers”?
non- fruiting shoots that emerge from old wood. they are normally removed
stages of grape development
- Early growth
- véraison
- ripening
- extra-ripening
What happens in the grape during the early-ripening?
- Tartaric and Malic acid accumulate
- some aroma precursors develop (methoxypyrazines)
- Tannin accumulation is encouraged by sunlight
- high water flow through the xylem
What is the effect of excess and limited water supply during the grape’s early ripening?
- Excess of water extends this period as shoot growth will be encouraged
- mild water stress will speed up this process, leading to a production of smaller grapes, but potentially, higher quality
What is the “lag phase”?
A slow down in grape ripening during véraison
What happens in the grape during véraison?
- Ripening slows down for a few days
- cell walls become more stretchy and supple
- chlorophyll is broken down and grapes change colour
When is green harvesting normally carried out?
During véraison, as the change in colour makes it easier to distinguish the less developed bunches
What are the benefits and risks of green harvesting?
- Benefit: achieve more concentrated (higher quality) grapes
- Risk: if there is a good water supply, the vine may compensate the loss by increasing the size of the remaining berried - dilution
What happens in the grape during its ripening?
- accumulation of sugars
- Malic acid degradation (encouraged by higher temp.)
- Dilution of Tartaric Acid
- Polymerisation of tannins (encouraged by sunshine)
- Anthocyanin synthesis (encouraged by sunshine)
- synthesis and accumulation of aroma precursors
- degradation of methoxypyrazines
- water flow is received only by the phloem
What happens in the grapes during extra-ripening?
- sugar transportation will stop
- berries will lose water through transpiration
- grapes will shrivel
- extra-ripe aromas will develop
define grape variety
a group of individual plants that can all trace back their lineage through a series of cuttings/layering to a single plant.
Define Clone
Each individual or group of vines that show a set of unique characteristics, even within the same variety
What are “founder varieties”?
Ancient varieties that have given birth to the enormous diversity that is grown today
what is clonal selection?
vines with positive mutations that are selected for future propagation
Factors that define the level of ripeness of the grapes
- Sugar levels
- Level of acidity
- profile of aromas
- Tannin ripeness
- wine style aimed for
Logistics factors (other than grape ripening) that influence the decision on harvest date
- Weather forecast
- availability of workforce
- disease pressure
- availability of vineyard/winery equipment
What is an intra-specific cross?
Cross of the same species
What is an hybrid?
A cross of two different vine species
What are the most commercially relevant hybrids for winemaking?
Orion, Phoenix, Regent, Rondo, Vidal Blanc
Examples of successful crossings
- Pinotage - Cinsault x Pinot Noir
- Muller-Thurgau - Riesling x Madeleine Royal
- Bacchus - Silvaner x Riesling x Muller-Thurgau
- Dornfelder
- St Laurrent
- Ruby Cabernet - Cabernet Sauv x Carignan
Examples of Teinturier grapes
- Alicante Bouschet
- Chambourin
- Colorino
- Petit Bouschet
Ways of propagating the vine
- Cutting
- Layering
Explain Field grafting
cuttings are grafted directly to already planted rootstocks. This is only practised in warm areas.
Also called chip-budding
What does “repiquage” mean?
It is a French term to describe the replanting of young vines among existing old vines. The reason for this is to replace a dead or ill vine
What is top-grafting?
A technique for changing varieties in a vineyard. The trunk is cut off at 500mm above the ground, a split is made, and two wedge-shaped pieces of the new variety inserted.
Cheap and quick alternative to replanting with a new variety
What are the characteristics of Phylloxera insect?
- Yellow aphid native to North America
- it is parthenogenetic - can lay eggs without male sexual attention , leaving up to 7 generations in a summer
- Its life circle adapts to its host
How does Phylloxera affect Vitis Vinifera?
It lays eggs below ground level and feeds on the vine’s roots, thus, weakening the plant by removing photosynthates and allowing damaging bacteria and fungi to further attack them
How does Phylloxera affect American Vine Species?
It can weaken the vines when it attacks their leaves, but these vines have roots that are uncomfortable to the insect, as their sap clogs up its feeding apparatus
When and where was Phylloxera first seen in Europe?
in 1863 in Hammersmith, London
Explain grafting
It is an ancient practice that takes advantage of the plants not having an immune system, thus, different varieties can grow as one.
Grafting involves the union of the scion and the rootstock. A callus is formed around this union which provides the cells through which vascular continuity is restored.
Both, scion and rootstock, maintain their genetic identity
Classifications to choose the correct rootstock
- nematode resistance
- Phylloxera resistance
- vigour
- drought resistance
- ability to withstand high soil lime content
Richard Smart’s Climate levels classification
- Macroclimate - Regional level
- Mesoclimate - subregion / vineyard
- Microclimate - individual vine level
GST Climate Classification
- Cool - GST 16.5°C or less
- Moderated - GST 16.5 - 18.5°C
- Warm GST 18.5 - 21°C
- Hot GST + 21°C
Climate classification by temperature and rainfall patterns
- Maritime - low annual differences in season temperatures. Rainfall is evenly spread throughout the year.
- Mediterranean - low temperature differences, but rain is concentrated in winter. Dry summers
- Continental - extreme differences between summer and winter temperatures. Short summers and cold winters
How does temperature affect bud-burst ?
- Bud-burst is stimulated by temperatures rising above 10°C
- it is best successful and uniform if there is a significant rise in temperature
- warm soils are associated with early bud-burst
- cold temperatures that bring frost at this period can cause extensive damage, and significantly reduce yields.
How does temperature affect flowering ?
- Warm temperatures (+17°C) promote successful and even flowering.
- cold damp conditions will result in poor fruit set - reduced yields
- not enough warmth may also result in less synchronised flowering leading to uneven ripening of the grapes.
how can extreme heat affect the vine?
- high temperatures increase the evapotranspiration of the vineyard
- if there is not enough water supply, the somata will close and photosynthesis will stop - stunting grape ripening and vine growth
What is the effect of sunshine on vine growth?
- Sunlight is essential for photosynthesis to happen
- Sunshine in spring is associated with successful flowering/fruitset
- sunshine throughout summer increases bud fruitfulness in the next growing season
Effect of sunlight on grape development
- promotes development of anthocyanins
- breakdown of methoxypyrazines
- greater tannin accumulation pre-véraison and further polymerisation post-véraison
- synthesis of positive aroma precursors/compounds
- sunshine warms the grapes, therefore, promotes malic degradation
- prolonged periods of sunshine and high temperature can lead to sunburn
Effect of Latitude on sunlight
- the lower latitude, the more sunlight hours per annum
- the lower the latitude, the more intense the solar radiation
- low latitudes will receive similar daylight hours throughout the year. High latitude ones have longer daylight hours during summer and shorter ones during winter.
Latitude range in which vineyards for wine production are normally located
Between 30 and 50 degrees north and south the Equator
Effect of altitude on temperature
- Temperature fall approximately 0.5-0.6°C per 100m rise
- at higher altitude there is quicker heat loss overtime - higher diurnal range
Effect of latitude on sunlight
solar and UV radiation is more intense at higher altitudes