Effect of Three Roots tocks on Grapevine (Vitis vinifera L.) CV. Négrette, Grown Hydroponically. I. Potassium, Calcium and Magnesium Nutrition

In order to study the lack of acidity in wines made out of cv. Negrette, a problem partially due to a high potassium content, this cultivar was grafted onto three different rootstocks, which were then grown in a nutrient solution.  Although cation nutrition varied as a function of the rootstock, the potassium level was high in leaves of all three rootstocks. Rootstock 3309 C induced the lowest potassium level. Furthermore, in combination with Negrette, SO 4 absorbed potassium more readily than 101-14 Mgt, contrary to the literature concerning other cultivars. To decrease the absorption of this element by Negrette, 3309 C appears to be the most appropriate rootstock.