Wine lect9
- 1. 9/19/2012 Introduction to Vines and Wines Hort/VE 113 Fall 2012 Session 9-Grape Development and ripening Grape Structure A grape cluster is a complex flower, or inflorescence, that consists of a peduncle, cap stems (also called pedicels), a rachis, and berries that arise from individual flowers in the flower cluster. • Each individual Grape Structure berry is made up of skin, flesh (or pulp), and seeds. On the outside of the skin is the bloom, or waxy y layer, that helps to prevent water loss 1
- 2. 9/19/2012 Vine growth stages • Budbreak (leaf growth) • Bloom • Berry set • Shatter • Veraison • Fruit maturation • Leaf fall Budbreak • vine begins the process of bud break in spring (March) • first sign of green in the vineyard emerges • form of tiny shoots Flowering-flower development Depending on temperatures, 40-80 days after bud break(May) flowering begins with small flower clusters appearing on the tips of the young shoots looking like buttons. 2
- 3. 9/19/2012 Flowering Fruit set • follows flowering almost immediately • the fertilized flower begins to develop a seed and grape berry to protect the seed • In th North-May, South- the N th M S th November • stage is very critical for wine production since it determines the potential crop yield • Not every flower on the vine Photo credit:Fir0002/Flagstaffotos gets fertilized; unfertilized flowers eventually fall off the vine. Fruit set • percentage of fertilized flowers 30 up to 60 or much lower. • Cli Climate and vine h l h d i health important! • low humidity, high temperatures and water stress can severely reduce the number of flowers that get fertilized. 3
- 4. 9/19/2012 “Shatter” aka “Coulure” • caused by a CH2O deficiency in the Vine • causes the vine to conserve resources that would otherwise be funneled into the developing grape berries. • Makes berries fall off • A natural process Bad weather (cold or hot) during and right after bloom • Can get out of hand can make this a problem! ‘Malbec’ sensitive to shattering If it’s hot-faster shoot growth and more respiration Uses up available carbohydrates normally devoted to grape development 4
- 5. 9/19/2012 Stage 1 •BERRY DEVELOPMENT STARTS SOON AFTER FERTILIZATION OF THE FLOWER. •CHARACTERIZED BY STRONG GROWTH OF THE SEED AND BERRY •AT THIS POINT, THE FINAL NUMBER OF CELLS IN THE BERRY IS DETERMINED •ACIDS ARE ACCUMULATED •ENVIRONMENTAL IMPACTS ON BERRY DEVELOPMENT PROCESSES(SHATTER) OCCUR HERE Stage 2 •ALSO KNOWN AS THE ‘LAG’ PHASE •THE BERRY ITSELF GROWS SLOWLY •DURING THIS PERIOD THE EMBRYO WITHIN THE SEED MATURES •THE SEED COAT LIGNIFIES •TOWARDS THE END OF THIS STAGE, AS VERAISON APPROACHES, BERRY CHANGES COLOR Veraison • Grapes are about half their final size when they enter this stage. • beginning of the ripening process • normally takes place around 40-50 days after fruit set. – North-late July into August; South-late January into February • Within six days of the start of veraison, berries begin to grow dramatically as they accumulate glucose and fructose and acids begin to fall. 5
- 6. 9/19/2012 Veraison • Grapes become their final colors – red/black or yellow/green depending on the grape varieties. varieties • color change due to: berry skin chlorophyll replaced by: – Anthocyanins (red wine grapes) – Carotenoids (white wine grapes). Stage 3-Berry ripening •THE PERIOD OF RAPID CELL EXPANSION AND SUGAR ACCUMULATION. •POTASSIUM, AMINO ACIDS AND PHENOLIC COMPOUNDS INCREASE •MALIC ACID IS DEGRADED •MOST FLAVORS ARE DEVELOPED Engustment • During engustment, the berries start to soften as they build up sugars. • the cane of the vine starts to ripen as well changing from green and springing to brown and h d d hard. • The vine begins to divert some of its energy production into its reserves in preparation for its next growth cycle. 6
- 7. 9/19/2012 Veraison onset • The onset of veraison does not occur uniformly among all berries. • Typically: – berries and clusters that are most exposed to warmth, on the outer extents of the canopy, undergo veraison first – berries and clusters closer to the trunk and under the canopy shade undergoing it last. http://www.youtube.com/watch?v=nv4ZTKpApyY Veraison onset • For the production of high quality wine, it is ideal to have an earlier veraison • The vine is biologically programmed g y p g to: – channel all energies and resources into the berries • Houses seedling offspring • Increases chance of survival Controlling veraison onset •Vineyard factors that can control the onset of veraison: –limited water stress –canopy management that creates a high "fruit to leaf" ratio •can encourage veraison 7
- 8. 9/19/2012 Controlling veraison onset • very vigorous vines – have lots of leaf shading for photosynthesis and water supply • Can delay the start of veraison – vines energies are directed towards continued shoot growth of new buds. Summary • The grape berry: independent biochemical factory that contains: water, sugar, amino acids, minerals, and micronutrients. • Synthesis of other components like flavor and aroma compounds also occurs in the berry. b • Great deal of variability between: – berries within a cluster – clusters within a vine – vines within a cultivar (clone) – between vines within a vineyard 8
- 9. 9/19/2012 Summary(cont.) • Determination of berry ripeness can be difficult due to variability. • The main objective of the g j grower is: – achievement of a uniformly ripe crop – with great flavor and aroma compounds. Summary(cont.) • The berry itself has three main tissues that comprise it: flesh, skin, and seed. • Each tissue contributes differently to overall wine composition. • Composition can be manipulated by changing berry size • Other factors such as the number of seeds, environment, and nutrition also affect final wine quality. Summary(cont.) •every one of these components is tied initially to successful flower fertilization. •For the grape vine, reproduction is the number one purpose to exist. •Humans manipulate this process for their benefit! 9
- 10. 9/19/2012 Human manipulation of ripe grapes Hour exam next class! • Worth 100 points • Short answers • Identify grape/grapevine parts y g p g p p • Study guide posted today(Thurs.) by 3pm • Questions? 10