The Effect of Rootstock on the Partitioning of Dry Weight, Nitrogen and Potassium, and Root Distribution of Cabernet Sauvignon Grapevines

Abstract

All organs of Cabernet Sauvignon grapevines grafted onto Aramon Rupestris Ganzin No. 1 (AxR 1 , Rupestris St. George (St. George) and 5C Teleki (5C) were harvested on a single date and analyzed for potassium and nitrogen concentrations. In addition, the distribution of roots in the soil profile of all three rootstocks were mapped and measurements of leaf net CO₂ assimilation taken on replicate vines. There was no effect of rootstock on the partitioning of dry matter among the organs of these vines, with the exception of the trunk. There also was no effect of rootstock on the concentrations of potassium in these organs. The rootstock with the lowest N concentration in the root system also had the lowest N concentration in its fruit. There were large differences in the number of root intercepts among the rootstocks, with AxR 1 having the lowest number and St. George having the greatest number per soil wall profile. There were no apparent differences in the distribution of roots of any dimension within the soil among the rootstocks. There was a significant reduction in the stomatal conductance of leaves on vines grafted onto AxR 1 compared with the two other rootstocks. The results indicate that rootstock had no effect on the partitioning of dry matter and the concentrations of N and K in the organs of mature Cabernet Sauvignon vines at this location. The lower density of roots in the soil profile of the AxR 1 rootstock may have affected the gas exchange of the scion.