Chemical Bonds of Cations in Grapevine Berries and Stems of Some Important Cultivars of Vitis vinifera (L.) and Their Relevance for Viticulture and Enology

Abstract

Cations are essential for plant growth, tissue build-up and its stabilization. Divalent cations are necessary for cell wall stability and other interstitial tissues. They may be cross-linked with pectins or form looser ionic bindings. This is of importance for grape processing during the technical operations of juice extraction. Monovalent ions are more involved in vacuolar homeostasis and pH stabilization.With a specific extraction procedure H2O-soluble, 1N NaCl-soluble, 2% CH3COOH-soluble, and 5% HCl-soluble fractions as well as the total content of K, Ca, and Mg were analyzed in grapevine berries and stems. The monovalent K is only found in the water and the NaCl fraction; both in berries and stems. But only 50-60% of the total K can be extracted with both solutes. The divalent cation Ca is found in all four fractions with differing amounts, but water soluble Ca is in most cases highest. Ca may also have an indicator value for BSN, because the water soluble fraction is lowest in the most susceptible variety. Mg is not found in HCl fraction.An analysis of variance shows that the varieties have a significant influence on nutrient distribution in different tissues. It seems that the relation Ca/Mg (NaCl fraction) in stems is a good indicator for BSN because susceptible varieties show lower ratios than resistant ones. Some more research is necessary to clear up this possible relationship.