NH - Unit 2 - The Vine - Varietal selection and propagation Flashcards
Where can 19th century vines be found that still produce high quality grapes?
South Australia, California
When selectiing vines, the main criteria used are :
- Climate adaptation - cold, short growing seasons, drought etc.
- Resistance to disease - phylloxera, nematodes, mildews, oidium, botrytis
- Adaptation to soil conditions (either ungrafted or grafted vines w/rootstocks) - lime, drought, acidity, salt
- Economic characteristics - high yield, high quality, ability to mechanise
Where did the original cultivated vine ,vitis vinfera sativa, originate?
why?
- transcaucasia
- it had functional hermaphrodite flowers => better yields
Vine hybridisation
- The crossing of V. Vinifera with other Vitis species.
- With the spread of phylloxera, hybrid rootstock were created to make the most out of rootstock.
- Widely used in eastern USA still due to winter cold resistance.
Where did vine hybridisation by grafting between different species begin?
Why?
How?
- In the Europe in the late 19th century
- because the vinifera rootstock was not intolerant for phylloxera
- nurseries developped a large number of hybrid rootstock by crossing V. berlandieri (high calcium tolerance) with V.ripiera and V. rupestris (phylloxera resistant, graft well)
Where did vine hybridisation by interbreeding between different species begin?
Why?
How?
- In the USA
- early setters found that condidions fo V.F. were unsuitable
- they were able to interbreed with indigenous species such as V. Riparia, V. labrusca, V. aestivalis
Why did Europe abandon the productiion of wine from interspecific hybrids?
- the downy-mildew resistant hybrids that were created sinds the introduction of this disease, imported from USA in 1878, produced good yields, had some mildew resistance and some could be planted unfrafted so the became very popular. e.g. 1950 hybrids occupied 30% of French vineyards.
- => sever overproduction problems of poor quality wine
What is special about Regent?
- It is a hybrid
- the 6th most planted grape in Germany
Why are hybrids still used widely in eastern USA?
Due to their high winter cold resisitance.
What are intraspecific vinifera crosses?
Give 2 examples :
The crossing of two vinifera varieties to create entirely new varieties.
e.g Aramon x Teinturier = Petit Bouschet,
Riesling x Madeleine Royal = Müller-Thurgau
What are “teinturiers”?
A grape variety that accumulates anthocyanins in the pulp as well as in the skin, which gives a deep red juice on pressing.
Used by Louis Bouschet for his crossing “Petit Bouschet” (Aramon x Teinturier)
Later further crossed by his son Henri Bouschet for his crossing Alicante Bouschet (Petit Bouschet x Grenache)
What is mass selection?
- The traditional method for selecting vines in which only the desirable plants are selected from which to take cuttings => done by passing trough the vineyard before harvest
- Best done in poor years - can eliminate stock rather than select.
What is clonal Selection, when first carried out?
- plants originated from a single parent.
- propagated vegetivaly => usually by cuttings
- genatically identical
- first carried out on Silvaner (Froelich in 1876)
- up untill 1950’s only in Germany
- now worldwide
Clonal selection criteria
• Yield
- bud fertility, size of berries, success of berry set
- Sugar & acidity concentrations
- Quality of phenolic & aroma compounds
- Resistance to disease, cold & drought
- Freedom from viral infections (fan-leaf, leaf-roll, fleck, vein necrosis, corky bark, stem pitting)
- Ease of grafting
- Cost
How is clonal selection carried out?
- Cuttings are taken from just a few vines from carefully monitored mass-selected vineyards.
- Propagated in controlled conditions, carefully selected.
- Growers plant rather fewer than 10 clones of a variety than poly-clonal populations
Disadvantages of clonal selection
- Closely related vines in the same area will allow for easy spread of disease.
- Some clones are very specialised and only suitable for certain regions/styles of wine.
- Clonal selection has led to in increase in yield, leading to overproduction.
- Led to reduction in vine genetic resources.
What is genetic modification?
- The transfer of genes from one organism to another
- the modification of genes within an organism
Explain the use of genetically-modified vines in commercial vineyards.
- No genetically-modified vines are currently available for use in commercial vineyards.
- Research into improving disease resistance occurs in viticultural research institutes
Why are vines not often planted as seeds?
- propagation from cuttings is quicker and easier
- allows for grafting on the phylloxera-resistent rootstock
- it is difficult to predict the characteristics of plants grown from seeds (unless controlled pollination techniques have been used)
What is the advantage of vine nurseries?
- the possibility of testing plant material prio to sale.