It is said that - 'quality wine is created in the vineyard'. Except for the usual references too 'terroir' - very little is written about the role that viticulture (the connecting link of the actual plant / vine) plays in wine quality. It is a huge topic..., but what better place to start, than with the vine itself - and more importantly its roots.
It is a little known fact that the majority of grape vines planted world-wide use the roots of another vine to extract the water and nutrients they need. When you visit a vineyard; the vines you see above ground, whether they be; Sauvignon Blanc, Chardonnay or Syrah - actually belong to the European vine species, 'Vitis vinifera'. However below ground, the roots of these vines belong to another species altogether.

 

The roots of 'Vitis-Vinifera' are acutely susceptible to 2 devastating soil borne pests; the dreaded louse known as 'Phylloxera' and the lesser-known but far more widespread microscopic roundworm called 'Nematodes'.
European winemakers found this out with devastating effect in the 1860's when Phylloxera, native to north America, was unintentionally introduced. It resulted in the death of millions of vines across Europe.
A solution was found, as many of the wild vine species native to the USA had built up a natural resistance to Phylloxera. These obscure relations to the European grapevine are in fact scrawny, sprawling vines. However, by grafting the wine grape Vitis vinifera onto the roots of these species (or their crosses), it was found that the resulting vine could withstand the damage of phylloxera.
Later it was found that vines grafted onto various rootstocks grew better in saline, acidic, clay, limestone or drought prone soils, and most produced much higher grape yields compared with vines grown on their own roots. Some experts claim that they can actually taste the difference between un-grafted vine grapes and grafted grapes.
So next time you visit a winery, as well as asking what oak they use, also ask if their vines are on rootstock and if so, which one? It is a good question as the rootstock on which the grapes grow, have an impact on the character of the wine you are drinking.