Chapter 2 The Vine Growth Cycle Flashcards
(33 cards)
Define dormancy
A period during which the vine sustains Itself with carbohydrates stored in the roots, trunk and branches. It starts with leaf fall and ends with budburst in spring.
Why does dormancy happens?
Average air temperatures below 10 ° C are too cold for the vine.
North: November – March
South: May - September
Define budburst
The end of dormancy. Buds swell and open and green shoots start to emerge.
North: march-april
South: September – October
What affects budburst?
- Air temperatures above or equal to 10° C.
- Higher soil temperatures because of dry free draining soil encourage budburst: sandy soils.
- Delaying pruning in winter can postpone budburst.
- Some varieties have different temperatures: early budding or late budding.
Define shoot and leaf growth
The growth and development of shoots, buds, leaves and inflorescences. Vigor is the term that describe vegetative growth.
How does shoot and leaf initially happens?
Initially thanks to the carbohydrates located in the roots, trunk and branches.
Define vigour/ vigor
The growth of shoots, leaves and lateral shoots. Higher vigor- longer shoots and bigger leaves.
What does vigour depends on?
Vigor depends on:
1. Resources available: temperature, water and nutrients.
2. Planting material: variety, clone, rootstock
3. Presence of disease.
Define flowering
The development of flowers or inflorescences. The opening of individual flowers in an inflorescence. This leads to pollination. Pollen-landen stamens are exposed and the pollen lands on the stigma surface.
What affects flowering?
Warm temperatures: minimum 17° C
Rain, clouds, wind and cold temperatures are adverse conditions.
Define fruit set
The transformation of flowers into grapes through pollination and pollen germination.
Explain fruit set?
After pollination individual pollen grains germinate and each grain transforms into a pollen tube. The pollen tubes penetrate the stigma and the ovule. The eggs are fertilized. This leads to the formation of a grape berry with up to 4 seeds (from the fertilized ovules) The wall of the ovary form the skin and pulp of the grape.
Define bud fruitfulness
The number of inflorescences that will develop from a bud in the next growing season.
Describe bud fruitfulness?
The conditions during the part of the growing season where the compound buds develop on the new shoots can have a substantial influence on the next year’s yield.
Describe pollination
The process where pollen grains are shed by the male part of the flower and come in contact with the female part of the flower.
How does pollination work?
The stamen (anther + filament) are full of pollen and exposed. The pollen grains are shed and land on the moistened stigma surface.
Define coulure
A condition of the grape bunch in which a high proportion of flowers has had a failed fruit set.
Why does coulure happens?
When ovule fertilization is unsuccessful and therefore no grape develops. It’s caused by a low level of carbohydrate due to:
1. Low rates of photosynthesis (cold, cloudy conditions or hot, arid conditions).
2. Vigorous shoot growth using too much carbohydrates. (fertile soils or use of fertiliser)
3. Some varieties are naturally susceptible
Define millerandage
A condition where a high proportion of grapes are seedless and as a result smaller. Some grapes can stay green and unripe.
Why does millerandage happen?
Cold, wet, windy weather during fruit set specially with some varieties.
Define early grape growth
A stage during the growth cycle after fruit set. Hard green grapes start to grow. Shoot grow continues during grape growth but slower.
What changes during grape growth?
- Grapes grow in size.
- Tartaric and malic acid accumulate.
- Some aroma compound and aroma precursor develop.
- Tannins accumulate. They are very bitter.
- Water flows into the grape.
What can prolong or speed up grape growth?
Prolong: too much water and nitrogen. They encourage shoot growth and delay grape repenting.
Speed up: mild water stress. This can lead to small grapes with more skin to pulp ratio. Can be good in some red wines.
Define aromas precursors
Compounds with no aromas that will become aromas compounds during fermentation.
