The significance of scion x rootstock interactions

by | Sep 30, 2019 | South Africa Wine Scan

In this study, researchers wanted to determine how consistently rootstocks affect the growth and fruit composition of scion varieties and identify scion x rootstock interactions.


  • Drip-irrigated, spur-pruned Chardonnay, Cabernet-Sauvignon and Shiraz, grafted on seven rootstocks, in a hot-climate, was assessed over five seasons from 2013 to 2017.
  • The study was conducted with mature vines, established in 2006, as a randomised block design with five replicates.
  • Rootstocks included Ramsey, 1103 Paulsen and 140 Ruggeri and four promising selections from the CSIRO rootstock development programme.
  • Vines were trained as quadrilateral cordons on a two-wire vertical trellis of height 1.8 m and 3.0 m row × 1.8 m vine spacing, and irrigated with 5.5–6.0 ML/ha of water each season.
  • Each variety was harvested at 25.0 °Brix.
  • Vine performance and fruit composition was evaluated.


  • Despite identical management practices, there were large differences between scion varieties in key growth characteristics (yield, pruning weight and Ravaz Index) across rootstocks.
  • Effects of rootstock on growth characteristics were smaller than the effects of variety.
  • The effect of rootstock on bunch weight and berries per bunch was consistent across scions.
  • There were significant effects of both variety and rootstock on yield, number of bunches, bunch weight, berry weight (scion only), berries per bunch, pruning weight and the Ravaz Index (yield/pruning weight).
  • Significant effects of variety and rootstock on fruit composition, included pH, titratable acidity (scion only), malate, tartrate (scion only), yeast assimilable nitrogen (YAN); and for the red varieties, total anthocyanins (scion only) and phenolic substances (scion only).
  • Significant interactions between scion variety and rootstocks were found for yield, number of bunches, berry weight, pruning weight and Ravaz Index.
  • Significant scion × rootstock interactions were also found for pH and YAN.
  • For each variety, significant effects of rootstock on fruit composition were linked to growth characteristics. However, these relationships, based on correlation analyses, varied for each scion.


The study has shown that the performance of scion varieties, and to a lesser degree the fruit composition, is dependent on rootstock choice. The inherent vigour of the scion variety must be considered in rootstock selection. Furthermore, individual scion/rootstock combinations may require specific irrigation, pruning or canopy management to achieve vine balance and optimise fruit and wine composition.


Clingeleffer, P., Morales, N., Davis, H., & Smith, H. (2019). The significance of scion × rootstock interactions. OENO One53(2).

This abstract has been reproduced from its original form as permitted by the Creative Commons license: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). Minor changes were made to the headings and the abstract was shortened by omitting some text.

Image: rootstock x scion. (Image source:

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