It is of fundamental importance for the excellent success of a vineyard to choose i rootstocks appropriate, characterizing the balance of the plant as a function of the type of soil.
In our country approx 40 rootstocks are authorized and alongside the classic ones in recent years new ones have been developed.
But why do I have to graft?
With the advent of Phylloxera (Phyllossera Vastatrix), a parasitic aphid on the vine, viticulture has been revolutionized since the end of the 19th century, as this parasite has managed to decimate vineyards throughout Europe with the exception of a few particularly sandy or volcanic soils. Its damage was particularly noticeable on the roots of European vine (Vitis Vinifera).
These show knots, tuberosity and rot, up to the complete destruction of the root system.
After a few years and numerous attempts, the American vine was found to be more resistant to phylloxera.
On American vine rootstocks this parasite mostly attacks the leaves, giving rise to the formation of galls. The roots, on the other hand, are affected in a milder and less worrying way.
Then, following the technical intuition, it was decided to use the American vines as rootstocks of the European vine.
American species as rootstock….
The American vine species identified at the beginning of the last century as rootstock were: Repair, Berlandieri And Rupestris.
Subsequently, thanks to genetic improvement techniques, hybrids of these three species were created, obtaining a two-way hybridization: Riparia x V. rupestris, Berlandieri x V. riparia and Berlandieri x V. rupestris.
From these three crosses groups of rootstocks were created, improved over time with further hybridization processes.
The rootstocks of the vine, in addition to resistance to phylloxera, must also have good requirements with respect to other factors such as adaptability to the soil, grafting affinity to the Vitis Vinifera variety and vigor.
The right choice is important, since these have the role of regulators of the assimilation of water and nutrients and also resist deficiencies, thus allowing cultivation even in difficult conditions.
Rootstock - Soil
The biggest problem is the excess limestone present in the soil which can cause the ferric chlorosis.
Already with a presence greater than 10%, problems can be encountered by some rootstocks with a soil pH equal to 8.
The water stagnationo and the strong surface humidity can lead to root rot and poor production quality.
Also there salinity it is another problem not to be underestimated with the presence of sodium chloride, sulphates, potassium and magnesium chlorides.
Finally we have the Drought, an increasingly common condition in soils located in the hills without artificial irrigation, which can be contrasted with deep root systems and small woody vessels.
Rootstock - Variety
In the wine-growing areas affirmed this problem does not arise, as the rootstocks used are similar to the typical vines of the area.
Vigor
There vigor of the rootstock it is generally synonymous with abundant production. However, the best quality is provided by the rootstocks of the vine of low or medium vigor, which induce less production.
The reduced vigor of the vine plants is compensated with the planting distances, which can be more intense, therefore with more vines per hectare.
The Magnificent 7
Even today i most used rootstocks and considered classics are 7, the result of the artificial hybridization of 3 American Vitis: Berlandieri, Riparia and Rupestris.
Berlandieri x Riparia
- Kober 5BB
- SO4
- 420 A
Berlandieri x Rupestris
- 1103 Paulsen
- 140 Ruggeri
- 775 Paulsen
- 779 Paulsen
Let's understand how to read the nomenclature.
For example, rootstocks Berlandieri x Riparia Kober 5BB (the most used in Italy):
- First name: indicates the seed-carrying vine (V. berlandieri)
- Second name: identifies the pollinating vine (V. riparia)
- Divider symbol: an "X" indicates that the hybridization is artificial;
- Name of the breeder of the hybrid (Kober in this case)
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