Growing Cycle Flashcards
Dormancy time frame
NH Nov-March
SH May-Sept
Dormancy needs and adverse conditions
Needs:
1) temps below 10C/50F
Adverse:
1) extreme cold (below -20C/-4F will damage vine, below -25C/-13F will kill vine)
2) unusually mild temperatures
Dormancy management
- winter pruning
Budburst time
NH March-April
SH Sept-Oct
Budburst Needs and Adverse Conditions
Needs:
1) air and soil temperatures over 10C/50F
Adverse Conditions:
1) frost
2) cold soils
What factors determine when Budburst happens?
1) air and soil temperatures
2) grape variety
- early budding: chardonnay, pinot noir, merlot, grenache
- late budding: sauvignon blanc, cabernet sauvignon, syrah
3) when winter pruning occurs
- later = later budburst
What is happening in the vine during dormancy and budburst?
As the soils reach above 10C/50F the plant is powered on starch and carbohydrates stored in the roots, trunk, and branches
Shoot and Leaf Growth timeframe
NH March-July
SH Sept-Jan
Shoot and Leaf Growth Needs and Adverse Conditions
Needs:
1) stored carbohydrates
2) warmth (cooler springs lower overall potential to ripen)
3) sunlight (warmth and sun needed for photosynthesis as leaves develop)
4) nutrients (nitrogen, potassium, phosphorus)
5) WATER
Adverse Conditions:
1) low carbohydrate levels
- excessive leaf removal
- water stress
- mildew infections
- excessive yields (all previous growing season)
2) water stress (limits photosynthesis thus shoot growth)
= stunted shoot growth which causes
1) small, weak shoots
2) reduction in leaf numbers and/or size
3) inflorescences that don’t flower properly
4) grape bunches that do not flower properly
Describe vigour
A vines vegetative growth
Depends on:
1) natural resources available (temp, water, nutrients)
2) planting material (variety, clone, rootstock)
3) presence of disease (viruses can lower vigour)
- many canopy management choices are made concerning vigour
- fastest rate of growth is between budburst and flowering
Optimum temperature range for photosynthesis
18-33C / 64-91F
Flowering and fruit set time frame
NH May-June
SH Nov-Dec
Flowering and fruit set needs and adverse conditions
Needs:
1) warm temperatures (minimum 17C/63F to signal pollination)
2) sunlight, water, and nutrients for bud fruitfulness next season
Adverse conditions:
1) rainy, windy, cloudy conditions
2) cold temperatures
3) water stress
When does flowering begin and how long does it take?
Flowering begins within 8 weeks of budburst but is entirely temperature dependent. Temperatures over 17C/63F flowering can start and finish in a few days, but with cooler temps it can take weeks leading to uneven flowering.
Describe flowering and fruit set
Flowering:
The opening of the individual flowers of an inflorescence, exposing the pollen-laden stamens which shed pollen grains on the moistened stigma. Here they germinate, each pollen grains producing a pollen tube. (Cold, rain, wind and water stress can negatively affect pollen tube growth) The pollen tubes penetrate the stigma and ovule (female reproductive cells) in the ovary and deliver the sperm cells that fertilize the eggs in the ovule.
Fruit Set:
The transition from flower to grape as the wall of the ovary enlarges to form the grape skin and pulp. The ovules form seeds, up to 4 per grape.
What does flowering in fruit set effect in the current and following growing season?
Current: Yield and quality
Next season: Compound bud fruitfulness can be limited by 1) shade 2) low temps (under 25C/77F) 3) water stress and 4) nutrient deficiency
Optimum temperature range for flowering
26-32C / 70-90F
What % of flowers become grapes? What are some issues with flowering?
30% (0-60%)
Coulure: fruit set fails for a high proportion of flowers due to an imbalance in carbohydrate levels bc of decreased photosynthesis (cold, wet, water stress) or excessive vigour (Grenache, cab Sauv, merlot, Malbec)
Millerandage: high proportion of seedless grapes due to cold and windy weather, reduced yields and under-ripeness (Chardonnay, merlot)
Grape Development time frame
NH June-Oct
SH Dec-April
Grape Development needs and adverse conditions
Needs:
1) sunlight
2) warmth
3) mild water stress
Adverse Conditions:
1) too much water/ nutrients
2) excessive shading of grapes
3) very cold/ hot conditions throughout the day/ night
Describe Early Grape Growth
- starts soon after fruit set
- hard, green grapes start to grow in size
- tartaric and malic acids accumulate
- aroma compounds and precursors develop (methoxypyrazines)
- very bitter tannins accumulate (sunshine promotes this)
- water flow via the xylem is very high
- shoot growth slows
What is the xylem
Transport tissue that delivers water and nutrients from the roots of the vine to the rest of the plant.
Important during early grape growth.
(Transpiration)
Early Grape Growth: too much water vs water stress
Too much water/ nitrogen: prioritizes shoot growth prolonging this stage and leaving less time to ripen
Too little: mild water stress speeds up this stage, leading to an even ripening of smaller berries, better skin to pulp ratio
Describe verasion
Grape growth slows for a few days (aka lag phase), the grape cell walls become more stretchy and supple, green-colored chlorophyll in skin cells are broken down, and black varieties start to turn red due to anthocyanin synthesis.
What happens during the ripening phase?
1) shoot growth slows substantially
2) cells expand rapidly
3) sugar and water accumulate
4) acid falls
5) tannins develop
6) color develops
7) aroma compounds and precursors develop
How does sugar and water accumulation work during ripening?
- sugar accumulation is rapid then slows
- sugar is produced in the leaves via photosynthesis (18-33C/64-91F & above 1/3 full sun)
- water flow via the xylem slows
- a sugar solution is transported from the leaves to the grapes via the phloem
- correlates with the rate of transpiration aka more transpiration = more sugar accumulation
How is acidity affected during ripening?
Malic acid is metabolized during transpiration and all acids get diluted
How do temperatures in the final month of ripening effect acidity?
Cool = slower transpiration = more acid
Temps above 21C/70F cause rapid acid loss
Temps below 15C/59F keep too much acid
How are aroma compounds affected during ripening?
- with proper heat and sun methoxypyrazines fall
- other compounds rise such as terpenes (floral, citrusy, grapey - muscat)
- synthesis, degradation, and retention of compounds is influenced by heat and light
- hotter climates = riper aromas
What happens to tannins during ripening?
They decrease throughout ripening due to polymerization (formation of chains) causing them to be less bitter, promoted by the sun
What happens to anthocyanins during ripening?
They increase during ripening, most rapidly with plenty of sunshine and temps 15-25C/ 59-77F
What does the length of ripening depend on?
1) grape variety
2) climate conditions
3) vineyard management (high yields, excessive shade, and still-growing shoots delay harvest)
4) time of harvest (human factors + climate conditions)
Harvest time frame
NH Aug-Oct
SH Feb-April
What happens during extra ripening?
- sugar transport via the phloem stops
- water loss through transpiration concentrates sugars
- extra ripe flavors develop
- grape shriveling in hot climates (syrah prone to shriveling)
