Concentrations of Amino Nitrogen and Soluble Carbohydrates in Bleeding Sap Collected at Bud Break of 'Cabernet Franc' and 'White Riseling' Grapevines Growing on Four Clonal Rootstocks

Abstract

Concentrations of amino nitrogen and soluble carbohydrates were measured in bleeding sap collected at bud break from 'White Riesling' clone Niederhausen 378 and 'Cabernet Franc' grapevines growing on either 3309C, 101-l4Mgt, SO4 or 5BB rootstocks at Kingsville, OH. Amino nitrogen concentration was higher in sap collected from 'White Riesling' compared to the more vigorous 'Cabernet Franc' The concentration of soluble carbohydrates in bleeding sap was highest on 'Cabernet Franc'/SO4 vines. Differences in xylem solutes could not be related to cropping in the previous year or to scion effects on vine vigor in the current year. Rootstock did not influence vine vigor in the year of this study. Shoots on 'White Riesling' vines had less leaf area at bloom, and were more fruitful due to the presence of clusters at more basal nodes on the shoot compared to 'Cabernet Franc.'