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Vine Reproduction

Vine Reproduction. Describe grapevine reproductive morphology and grapevine varietal differences Range: inflorescence primordial, buds, flowers, berries, clusters Describe the 18-month reproductive cycle of a grapevine. Inflorescence initiation.

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Vine Reproduction

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  1. Vine Reproduction Describe grapevine reproductive morphology and grapevine varietal differences Range: inflorescence primordial, buds, flowers, berries, clusters Describe the 18-month reproductive cycle of a grapevine tcreagh@eit.ac.nz

  2. Inflorescence initiation • The potential yield of a vine is determined approximately 16 months before harvest

  3. Inflorescence initiation • Inflorescence initiation starts in the buds as they develop and continue to develop for 8-12 weeks • Therefore the basal buds have potentially the most time to develop

  4. Inflorescence initiation • Inflorescence primordia and tendril primordia develop from the same initial structures, called anlagen, which are undifferentiated tissue • Environmental conditions and the interaction of hormones determines whether the anlagen will develop into inflorescence primordia or tendril primordia

  5. Inflorescence initiation • Inflorescence initiation occurs at about the same time as flowering • Therefore conditions at flowering also affect inflorescence initiation • In good conditions vines usually form two inflorescence primordia, but may form up to four

  6. Inflorescence initiation • Inflorescence initiation is favoured by: • Warm conditions

  7. Inflorescence initiation • Light • Increased light to buds and leaves increases fruitfulness

  8. (Source: winker, et al, (1974))

  9. Inflorescence initiation Optimum nutrient levels • Nitrogen, potassium and phosphorous deficiencies all affect fruitfulness

  10. Inflorescence initiation Carbohydrate levels • High vigour or drought can reduce the carbohydrate levels reducing inflorescence initiation

  11. Inflorescence initiation • The location of the bud • Generally the primary bud has larger and more inflorescence primordia as it is the most well developed • Buds located at nodes 4-10 potentially tend to have more inflorescence due mainly to the temperatures and time of development

  12. Figure 5.2: fruitfulness along a cane

  13. Inflorescence initiation • These factors have implications for pruning • For example, particularly in cooler climates cane pruning is favoured to achieve maximum fruitful buds

  14. Inflorescence initiation • Where low crops are desired, for example in premium cabernet sauvignon spur pruning may be favoured • Canes that have grown in sunlight are generally selected, as they have many potentially fruitful buds

  15. Flowering and Fertilisation Figure 5.3: bloom sequence of grape flower: (a) calyptra attached, (b) calyptra separating, (c) open flower (after Babo and mach, 1909) (Source: weaver, 1976)

  16. Flowering and Fertilisation Figure 5.4: flower types: (a) hermaphrodite, (b) female, (c) male (After Babo and mach, 1909) (Source: weaver, 1976)

  17. Flowering and Fertilisation • V. Vinifera varieties generally have perfect or hermaphrodite flowers • These flowers have functional pistil and stamens so they are capable of self pollination

  18. Flowering and Fertilisation flower development • As buds swell in the spring the inflorescence primordia which developed the year before, begin to differentiate into flowers • Flowering usually occurs 6-10 weeks after the beginning of shoot growth • The flower is fully developed when the pollen is mature in the anthers. 

  19. Flowering and Fertilisation Pollination and fertilisation Definitions: • Pollination: • The transfer of pollen from the anther to the stigma

  20. Flowering and Fertilisation Fertilisation: • The union of male nuclei from the pollen to the female nuclei in the ovary 

  21. Flowering and Fertilisation • The first visual indication that pollination is occurring is when Capfall occurs • The pollen is released from the mature anthers this is termed cap fall and flowering is generally determined as when 80% cap fall occurs

  22. Flowering and Fertilisation • The pollen falls onto the stigma, then develops a tube which grows down the style to the ovary for fertilisation to take place • Fertilisation occurs 2-3 days after pollination

  23. Flowering and Fertilisation • The embryo and berry development begin • The embryo forms the seeds and the ovary becomes the berry

  24. Flowering and Fertilisation Fruit set • Fruit set is the transformation of flowers to fruit • Up to 70-80% of the flowers may fail to set • The size of the berry is largely determined by the number of seeds it contains

  25. Flowering and Fertilisation • The more seeds the larger the fruit • A berry may contain up to four seeds, although two or less is usual in the wine grape varieties • Berries with pistils that have not been fertilised will abscise from the cluster • This is termed shatter

  26. Flowering and Fertilisation • The timing and the duration of flowering are influenced by: • Climate influences • In warm climates, flowering will begin when the mean daily temperature reaches 20oC • In cool climates, flowering can last several weeks, and increasing day length is thought to stimulate flowering

  27. Flowering and Fertilisation • Warm, sunny, dry conditions favour pollen dispersal • Cold, wet days prevent cap fall reducing the level of fertilization • The growth of the pollen tube is also temperature sensitive • Pollen tube growth is slowed in cooler weather, leading to a reduction in fertilization

  28. The changes in berry development • The green stage (Stage I). • This is a period of rapid cell division leading to increased berry size. • The berry remains hard and green tcreagh@eit.ac.nz

  29. tcreagh@eit.ac.nz

  30. The resting stage (Stage II) • is a period of slow physical growth, but is the time seed development occurs. tcreagh@eit.ac.nz

  31. tcreagh@eit.ac.nz

  32. The ripening stage (Stage III) • The beginning of the ripening period is signalled by veraison. • The berry begins to soften and the colour of the berry changes due to colour pigment synthesis denoting the start of ripening. tcreagh@eit.ac.nz

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  34. The ripening stage (Stage III) • It is characterised by increasing berry size, but, sugar begins to increase (increasing Brix), acids decrease, and colour and flavour develop. • The berries become softer to touch and translucent in appearance. tcreagh@eit.ac.nz

  35. Acids • The rate of decline of malic acid may depend on: • Temperature • In hot climates, malic acid is metabolised more rapidly than in cool climates • As a rough rule of thumb, reaction rates for many reactions double or triple for every 10 degrees tcreagh@eit.ac.nz

  36. Acids • Cultivar • Some varieties, eg Cabernet franc, Chenin blanc, Syrah and Pinot noir, have proportionally higher malic acid • Riesling, Semillon, merlot, Grenache have higher tartaric acid content tcreagh@eit.ac.nz

  37. Acids • The total amount of tartaric acid in the berry reduces slowly as the berry ripens • However, tartaric acid levels decline compared to berry volume due to a dilution effect of increased in sugars and fluid in the cells tcreagh@eit.ac.nz

  38. Potassium • Potassium (K+) increases after veraison in the skin although the mechanism of uptake is not well understood • Potassium uptake increases the pH tcreagh@eit.ac.nz

  39. Phenolic Compounds • Phenolic compounds give colour, flavour, aroma and aging properties to wines, especially red wines • Phenolics are found in the seeds and skin, but are generally extracted from the skin during wine making • Anthocyanins are the specific phenols that produce colour in the berry skin tcreagh@eit.ac.nz

  40. Phenolic Compounds • Phenols are thought to be produced in the berry itself • They are not transported from other parts of the vine tcreagh@eit.ac.nz

  41. Phenolic Compounds • Anthocyanin synthesis depends on • Temperature • Sugar accumulation • Hereditary factors tcreagh@eit.ac.nz

  42. Nitrogen Compounds • During ripening the total nitrogen content of the berry increases due to an increase in ammonia cations, amino acids and proteins tcreagh@eit.ac.nz

  43. Aromatic Compounds • Aroma compounds develop late in berry development and many are found close to the skin • Ripeness and sun exposure have effects on these compounds tcreagh@eit.ac.nz

  44. Cultural and Climatic Influences on Berry Maturation Yield • Achieving a balance between yield, quality and vine health is essential • Yields have been increased by using: • Improved clonal material • Disease free material • Fertilisation, irrigation and pest control • However, increasing yield can reduce the vines ability to mature the fruit tcreagh@eit.ac.nz

  45. Yield Overcropping • Delays fruit maturity • Retains acidity • Retards anthocyanin synthesis • Reduces sugar accumulation and flavour development • Suppresses subsequent yields • May shorten vine life tcreagh@eit.ac.nz

  46. Yield Achieving an ideal yield depends on • The variety • Soil characteristics • Weather • The desired end product tcreagh@eit.ac.nz

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