Importing foreign varietals

This method has been very successful in the last few decades, as is shown by the world spread of varietals such as Cabernet Sauvignon and Chardonnay. This has brought out some surprising results as a cultivar's characteristics change drastically under different climatic conditions.

Mass selection ('Selection Massale')

This method involves passing through the vineyard before harvest and marking out those plants from which to take cuttings from. This is best done in poor years and can be carried out by eliminating plants instead of selecting them. This method was very common, but is now virtually abandoned due to the necessity to graft plants and the successes of clonal selection.

Clonal selection

Clones are plants originating from a single parent, which are propagated vegetatively (usually by cuttings) and therefore genetically identical. Clonal selection was first carried out by Froehlich in 1896 on Sylvaner. It was almost exclusively carried out in Germany up till the 1950s, but is now also done in France by ENTAV (Etablissement National pour l'Amélioration de la Viticulture) and by INRA (Institut National de la Recherche Agricole).

The criteria for selection are:

• Yield; bud fertility, size of berries, coulure etc.
• Sugar concentration
• Must acidity
• Phenolic and aroma constituents
• Sensitivity to disease, drought, cold etc.
• Organoleptic quality
• Freedom from viral infection, esp. fan-leaf, leaf-roll, fleck, vein necrosis, corky bark, stem pitting.

The following methodology was used by J Balthazar at INRA Colmar on Savagnin Blanc in 1976:

Visual inspection of 1700 plants
(Virus, coulure, yield, vigour, berry colour)
↓
Yield from 230 plants tested for sugar & acidity over 3 years
↓
Cuttings taken from 26 plants, grown in 7 varietal collections, 3 in Alsace,4 in Jura
10 plants per clone over 10 years
Virus testing- excluded 13
Micro-vinifications
↓
Only 4 clones selected

Visual symptoms are not enough for virus testing; use serological and immuno-enzymatic tests and grafting on to indicator varieties (e.g. 5BB). To eliminate viruses, thermotherapy can be used.

The life of a clone is 30 - 40 years due to spontaneous mutation and infection, but it can be withdrawn earlier if better performing clones are found.

There are some disadvantages in clonal selection:

• If all vines in the same area are closely related, the spread of disease is facilitated.
• Some clones are only suitable for certain regions.
• Clonal selection has led to an increase in yield leading to overproduction.
• It has also led to a reduction in vine genetic resources. To counter this, collections of old varietals have been established, both in the field and in vitro.

Selection by sexual reproduction

Very little hybridisation was carried out pre-Phylloxera, as it was not felt necessary. The only exception to this was the work of Bouschet (1824-1845) who crossed Aramon X Teinturier and produced Alicante Bouschet a good quality teinturier variety.

Hybridisation

Vine hybridisation between species (interspecific hybridisation) began in the United States. The early settlers found that conditions for the culture of V. vinifera were unsuitable and grew indigenous varieties such as V. riparia, V. labrusca and V. aestivalis. The wines produced were not very palatable as they were too harsh, foxy or herbaceous. Hybrids with V. vinifera were soon developed such as Concord, Black Hamburg and Clinton.

Interspecific hybridisation started in Europe with the development of rootstocks for grafting in the late 19th century. The problem was that V. riparia and V. rupestris are very Phylloxera resistant and graft well, but have a very poor calcium tolerance. V. berlandieri has a high calcium tolerance, but doesn't graft or root well from cuttings. To resolve this problem, nurserymen developed a large number of hybrid rootstock to cope with a wide range of soils.

The introduction of downy mildew in 1878 spurred other nurserymen to hybridise vinifera species with American ones and many thousands of hybrids were developed. The resulting hybrids produced good yields and had some mildew resistance, but the organoleptic quality of the wine was poor. In the late1950s, hybrids occupied 30% of the French vineyard area (400,000 ha). This led to severe overproduction problems. Due to the poor quality of the wine produced, most areas in Europe have forbidden the production of quality wines from interspecific hybrids and only approved a small number for the production of table wines.

Nevertheless, hybrids are still used widely in Eastern USA as they have a high winter cold resistance. Although the breeding of interspecific hybrids was abandoned in France and Italy in the 1950s, in Germany, the Institute for Grapevine Breeding Geilweilerhof, among others, has been carrying on the work up until the present day. Its present aim is to develop fungus-resistant cultivars that must be grafted on to Phylloxera-resistant rootstock, rather than developing a direct producer.
The most successful vines that have been developed at this institute are Phoenix, Orion and Regent.

Intraspecific vinifera crosses

These are crosses of one vinifera varietal with another. After Bouschet came Prof. Muller from Thurgau in Switzerland. He produced the Muller-Thurgau varietal by crossing Riesling and Madeleine Royale. This was a great success and presently occupies 20% of the German vineyard. The Germans developed many other vinifera crosses at their research centres at Geisenheim, Geilweilerhof and Freiburg: Scheurebe, Kerner, Reichensteiner etc.

Genetic modification

Some virus-resistant rootstocks have been produced, but these are not used in commercial vineyards.