D1 The vine growing cycle Flashcards
The vine growing cycle
The grape grower needs to produce grapes with adequate ripeness of sugars, acids, tannins and aromas.
The key is the balance of warmth, sunlight, water and nutrients.
1 Dormancy - Winter.
November-March NH
May-September SH
At temperature below 10 degrees the vine is dormant.
It sustains itself by using stores of carbohydrates, accumulated in the roots and trunk.
2 Budburst - Spring.
March-April NH
September-October SH
At temperature above 10C the bud burst.
The timing of bud burst depends on:
- air temperature
(the sharper the difference in season is the more even the crops will be)
- soil temperature
(the warmer the quicker) (dry free-draining soil warms up quicker than water-storing soil)
- Grape varieties, clone or rootstock (early budding and late budding)
- human factor
(winter pruning can delay budburst)
3 Shoots and leaf growth - Spring.
March-July NH
September-January SH
During spring the shoots and leaf start to grow.
Shoots growth is initially supported by the Carbohydrates stored in the roots from previous year. (excessive high yield from previous year can negatively effect shoot growth).
The leafs will then provide energy for further growth thought photosynthesis (optimum at 18-33C);
Water stress is not derisable at this time because can hinder photosynthesis and shoot growth, leading to unripe grapes therefore lowering yield and quality.
The vine’s vigour impact the speed at which the vine is growing.
The vine’s vigour depends on:
- Planting material
- Natural resourses
- disease (can lower vigour).
- canopy management
The vine needs nutrients such as:
Nitrogen, potassium and phosphorus.
Flowering and fruit set - Spring to Summer.
May - June NH
November - December SH
Optimal flowering condition are warm temperature (min 17C).
Vines are self pollinating.
A pollen stamen emerge and pollinate the stigma surface. Further, through the pollen tube, reach the ovule fertilising the eggs.
The optimal temperature for fruit set is 26-32C.
Too cold, cloudy and/or too hot, arid (water stress) condition can hinder photosynthesis, leading to imbalance of sugar, causing a poor fruit set and therefore reducing yield and quality.
Millerandage is a condition that can result from cold, wet and windy condition in which there is a high proportion of smaller, seedless and green grapes, causing low yield and poor quality.
Grape development - Summer
June - September NH
December - April SH
A mild water stress is desirable as it can encourage grape ripening rather than shoots growth, leading to riper grape and better quality.
Grape development is split in four stages:
- Early grape growth
- Veraison
- Ripening
- Extra ripening
The length of the grape ripening depends on:
- Grape variety and clone
- Climatic condition
- management of canopy and vineyard
- time of harvest (may depend on style of wine or weather conditions)
Early grape growth - stage 1
Sugar level are low.
Tartaric and malic acids accumulate.
Tannins accumulate and are very bitter.
Some aroma compounds develop, such as methoxypyrazines (herbaceous aromas).
Veraison - stage 2
The grape cell wall become stretchy.
The synthesis of anthocyanins begins (causing the black varieties to become red in colour)
Ripening - stage 3
Water and sugar accumulate.
As consequence, tartaric and Malic levels fall. (at min 15C)
Tannins Polimerise and become less bitter.
Aroma precursor and compounds develop ((like Terpenes (floral and citrus aroma)).
Anthocyanin synthesis develop further (15-25C).
Cold weather, clouds and shading and/or very hot and dry condition (water stress) can hinder the above.
Extra ripening - stage 4
Where climate is hot, sunny and dry, and disease pressure is low, grapes can be left on the vine to shrivel (water is loss through grape transpiration, concentrating sugar and developing extra-ripe aromas).
Define ripeness
Sugar, acidity, tannins and aroma compounds are influenced by the growing environment.
Sugar increase in warm and dry temperature conditions.
In contrast, acidity is better retained in cooler conditions (diurnal range may be considered).
Tannins and aroma are not related with temperature but with sunlight. Therefore, desired sugar and acidity level may be reached before the desired ripeness of tannins and aromas.
Reaching the desired level of tannins and aroma must be the main focus. It is easier to adjust sugar and acidity level than unripe tannins and aromas.
Phenolic = tannins and colour
