D1: The Vine Growth cycle 3 Flashcards
1) budburst: Northern hemisphere: march- april, southern hemisphere: september- october
2) shoot and leaf growth: march- july (northern), september- january(southern)
3) flower and fruit set: may- june (n), november- december (s)
4) veraison and berry ripening: july- september (n), january- march (s)
5) harvest: september- october (n), march- april (s)
6) winter dormacy: Dec- march (n), july- sept (s)
— this is the vineyard cycle and period, explain:
1) budburst: also called budbreak, marks the end of winter dormacy, buds swell and open
- – green pshoots start to emerge (ontstaan)
- compound buds form in the previous growing season. for buds to burst sufficiently high temperatures are needed (average air temperature approximately 10°c / 50°f)
- —– compound buds therefore generally remain dormant over winter and burst when temperatures rise in the spring
regions that have marked differences in temperature between the various seasons (eg continental climates) can be advantageous for succesful budburst.
– the rapidly increasing temp in the spring mean that budburst can be relatively uniform and this has positive implications for the homogenety of laer stages in the growing season. potentially eventually leading to a crop of grapes with even ripeness
in regions where there is often less contrast between winter and spring temperatures (for ex maritime climates), budburst can be less synchronised
- — when a few unusually mild winter days cause early budburst
- —– any cold days and frost that follow can potentially harm the newly burst buds, leading to lower yields
The timing of budburst depends on a number of factors:
1) air temperature: allready explained
2) soil temperature
3) grape variety
4) Human factors
what contributes the soil temperature to the budburst ?
1) higher soil temperatures around the roots, encourage earlier budburst
2) dry free draining soils, such as sandy soils, tend to warm up more quickly than water storing soils such as clay rich soils
- – this can be advantageous in cool climates, where an early start to the growing season improves the chance of ripening
what does the grape variety contributes to the budburst?
The average temp required for budburst depends on the grape variety.
example=
- erlot vines open at temp slightly lower than 10°c (50°f), whereas Ugni Blanc buds open at temp slightly higher than 10°c ``
Grape varieties that require relatively low temp at budburst are referred to as early budding
– chardonnay, pinot noir, merlot and grenache
Grape varieties that require higher temp are referred to as late budding
– S.B, Cab S, syrah
Because the buds of late budding varieties need higher temperatures to burst, they are less at risk of spring frost — time of budding is not always linked at time of ripening
- – a grape variety that is early budding is not necessarily also early ripening
eg: grenache buds early and ripens late
What does the human factors contribue to the
1) some viticultural practices can also advance or delay budburst
- carrying out winter pruning late in the dormant period can postpone (uitstellen) budburst
- — this technique can be used in areas where spring frost is a known problem
what about the shoot and leaf growth ?
During the spring and early summer, the shoots continue to grow, and leaves and inflorescences (a cluster of flowers on a stem) mature.
– the rate of shoot growth deterines the vigour (kracht) of the vine
– the fastest rate of growh generally occurs between budburst and flowering
–the speed of shoot growth can vary between vines and even within different parts of the same vine
what are carbohydrates contributing to the early shoot and leaf growth?
Carbohydrates stored in the roots, trunk and branches of the vine support the initial shoot growth.
– if these carbohydrates are low shoot grow can be negatively effected
example:
° caused by excessive leaf removal, water stress, mildew infections or high crop loads in the previous growing season
As leaves develop and mature, they provide energy for further growth via photosynthesis
– and therefore need adequate warmth and sunlight for this to take place.
!! most of the vine’s energy is directed towards shoot growth until flowering starts!!
As the vine grows, so does the vine’s need for nutrients:
- nitrogen
- potassium
- phosphorus
it’s important tha vines do not suffer from water stress in this time as this can limit photosynthesis and shoot growth.
yes
what about nutrient uptake through the roots in very dry soils ?
it’s impaired (verminderd)
What can cause stunted (belemmerd) shoot growth ?
1) small, weak shoots
2) reduction in leaf number or smaller leaves
3) inflorescences that do not flower properly
4) grape bunches that do not ripen fully
5) this can lead to poor quality and lower yields
what if shoots grow very long ?
They may be tucked within a trellis (if used) to ensure the canopy remains upright and avoid shading.
the parts of a vine flower is very important !!!
see printed picture
new buds develop at the base of the leaf stals (_____), on the growing shoots. Prompt buds will burst within the growing season producing new shoots called _____ . Compound buds will remain dormant until the _____ spring and provide the ______ for the next year.
1) petioles
2) Lateral shoots
3) next
4) shoots
SHading of compound buds, temperatures that are too low (under 25°c/77°f), water stress and nutrient deficiency (tekort), ….
Can all limit bud fruitfulness ( the number of inflorescences that will develop from a bud) in the next growing season.
— given that each inflorescence will become a bunch of grapes, the conditions during this part of the growing season can have a large influence on the next year’s yield.
—- Riesling for example is able to form potentially fruitful buds at relatively low temperatures making it well suited to cool climates
what is the proces of flowering and fruit set?
The yield and quality of grapes in the current growing season are strongly influenced by the processes of flowering and fruit set.
1) flowering describes the opening of the individual flowers within an inflorescence.
within this process:
a) the pollen laden stamens are exposed
- male part of the flower, made up of an anther and a filament
— filament: a long thin structure that supports an anther
— anther: flower structure in which pollen grains are produced
b) the pollen grains are shed and land on the moistened stigma surface
- — a process called pollination
c) on the stigma the pollens germinate (ontkiemen) and each pollen grain producing a pollen tube
d) these pollen tube penetrate the stigma and then the Ovule (the female reproductive cells in the ovary( eierstok)
e) The pollen tubes delivers the sperm cells, which fertilise the eggs in the ovule( eitjes)
f) the fertilised ovules form seeds, with up to four per grape
g) The wall of the ovary enlarges to form the skin and pulp of the grape
— fruit set is the term used to describe this transformation from flower to grape.
Cultivated (bewerkte) varieties of vines are normally self pollinating.
The pollen from the stamens of one flower is transferred to the stigma of the same flower, or a different flower in the same plant
insects and wind make little contribution to pollination in grapevines
Flowering typically takes place within eight weeks of budburst. however this is extremely temperature dependent:
warm conditions leading to earlier flowering.
— warm conditions (min temp of 17°c/ 63°f) are also favourable for succesful flowering. with these temp an individual inflorescence can flower within a few days.
Low temperatures can lengthen the duration of flowering, with weeks passing between the earliest and latest flowering
— this has a consequential negative effect on the evenness of ripening
What are the conditions for succesful fruit set ?
Not all flower become grapes.
- typically 30% of flowers will become grapes
- but this can range from zero to 60%
1) Pollen germination (ontkieming) requires warm temperatures (optimal 26-32°c / 79-90°f)
2) Pollen tube growth is negatively affected by cold, rainy, and or windy conditions and this can result in irregular fruit set and is a key cause of poor yields in cool climates
3) hot, dry and windy conditions leading to water stress in the vine can also have a negative effect,
- - again leading to reduced yields
What are the two common forms of irregular fruit set ?
1) coulure
2) millerandage
What is coulure ?
A condition of the grape buch in which fruit set has failed for a high proportion of flowers.
- this occurs when ovule (eicel) fertilisation is unsuccessful, and therefore no grape develops
- some coulure is normal, excessive coulure can reduce yield dramatically
Coulure is caused by an imbalance in carbohydrate levels.
- this can result from low rates of photosynthesis, which may be caused by cloudy conditions or hot arid conditions with high water stress
- — the vine stops photosynthesis to retain water
It can also result from vigorous shoot growth diverting carbohydrates from the inflorescence
- – very fertile soils
- heavy application of fertilisers and vigorous rootstocks can all cause strong shoot growth and therefore lead to coulure
Some grapevarieties are also naturally more susceptible to coulure than others
– Grenache, Cab S, merlot and malbec are all very susceptible
What is Millerandage ?
A condition of the grape bunch in which there is a high proportion of seedless grapes.
– the seedless grapes can still ripen normally, but are smaller than grapes with seeds
– millerandage may therefore reduce the volume of wine that can be produced.
- some seedless grapes stay small, green and unripe
- —which may be negative for wine quality
Millerandage can result from cold, wet, windy weather at pollination and fruit set
Some varieties are more susceptible than others like chardonnay and merlot
What are the grape development stages ?
1) Grape berry formation
2) Véraison
3) Ripening
4) extra ripening
how goes the grape berry formation ?
this is after fruit set
1) hard green grapes statrt to grow in size
2) tartaric and malic acids accumulate (opstapelen)
3) some aroma compounds and aroma precursors (compounds with no aroma that will become aroma compounds during the fermentation process)
- - methoxyprazines: contribute to herbaceous aromas in some wines (sb, cs cf)
4) tannins accumulate and are very bitter at this time, sunshine on the grapes promote tannin accumulation
5) sugar levels are low at this stage
6) water flow into the grape is high at this stage and it is mainly transported to the grape by the Xylem (a type of tissue (pipeline) that transfers water and some nutrients from the roots to other parts of the vine)
- - too much water and nitrogen can prolong (verlengen) this stage
- - these factors encourage shoot growth in preference to grape ripening
- – this causes delay for the ripening stage
- —- could mean that there is not sufficiant time for ripening before the weather becomes cold and rainy and the grapes need to be harvested.
so: mild water stress can speed up this stage and lead to the production of smaller grapes
- - reducing yields
- -greater skin pulp ratio
- – which in red wines can be associated with better quality (higher levels of tannins, colour, aroma compounds)
Grape grower decision:
- monitor and manage water levels through irrigation
- – to influence grape formation
7) shoot growth continues at this stage, but more slowly than early in the season
What are tartaric acids and malic acids ?
1) tartaric acids: Extreme important in winemaking
- unique, almost alone in grapes
- key role in maintaining (onderhouden) of the chemical stability of wine: colour and influencing the wines final taste
- strongest acid in wine with the ability to resist the impact of other acids in wine
2) malic acids: acid also found in apples
- sensitive to temperature
- respired during berry ripening
- the higher the temp, the more malic acid is respired
- - hot regions: 2g/l `
- - cold regions: up to 15g/l
What the vine need during berry ripening:
1) sunlight
2) warmth
3) mild water stress
adverse conditions:
1) too much water and nutrients
2) escessive shading of grapes
3) very cold or very hot conditions throughout the day and night
how goes the véraison ?
1) grape growth slows down for a few days (often called the lag phase)
2) the grape cell walls become more stretchy and supple
3) green coloured chlorophyll in skin cells is broken down and grapes of black varieties start to become red in colour and white varieties become translucent and golden
- — this happens due the synthesis of compounds called anthocyanins ( phenolic compound: the red blue and purple colour of berries)
Tell me about ripening:
most important vine process in determing final grape quality.
1) shoot growth should have slowed down substantially (hoofdzakelijk) by this time
2) cells expand rapidly: sugar and water accumulate and acid lvl fall
3) tannins, colour and a number of aroma percucors and aroma compounds develop
4) harvest usually marks the end of this stage
- august to oct N
- februari to april S
what about suggar accumulation ?
1) suggar accumulation is very rapid at the start of the ripening stage and then slows towards the end
2) sugar is produced in the vines leaves by photosynthesis
3) photosynthesis can take place at a maximum rate at temp between 18-33°c and at sunshine levels that are above 1/3 of full sunshine
— therefore in years with cold weather or constans cloud, rate of photosynthesis may hinder tsugar levels in the grapes
— by contrast very hot, dry conditions that can lead to extreme water stress can cause photosynthesis to slow or stop
During the ripening stage of grape growing cycle, water flow via the ____ slows down and a ____ solution (mixture of mainly ____ and ____) is transported by the phloem into te grape. what is a phloem ?
1) Xylem
2) sugar solution
3) sugar and water
phloem: a transport tissue that transfers sugars from the leaves to the other parte of the vine
