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.
SIGNIFICANCE OF THE STUDY:
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 One, 53(2). https://doi.org/10.20870/oeno-one.2019.53.2.2438
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Image: rootstock x scion. (Image source: https://www.ao.wine/vine-propagation-for-new-vineyard-planting)