The establishment of Cabernet Sauvignon trials in preparation for the evaluation of clonal response to climate and management
Abstract
The establishment of clonal trials takes a minimum of five years and often longer from planting to the first representative harvest. This project established trials to compare Cabernet Sauvignon clones in Margaret River, Coonawarra and the Barossa Valley in advance of formal assessment. The clonal composition was determined in consultation with the regional industry associations and with an aim to keep a strong similarity in the clones planted between the sites. The three trial sites will provide a significant resource for the systematic assessment of the impact of Cabernet Sauvignon clones on vine performance and grape and wine style.
Summary
The establishment of clonal trials takes a minimum of five years and often longer from planting to the first representative harvest. The South Australian Research and Development Institute (SARDI) and the other state Departments of Agriculture (or equivalent) developed and maintained these trials up until the early 1990s. Unfortunately, very few have been established since, making formal clonal evaluations of modern (recently imported or selected) clones difficult, as established trials are not in place when projects are initiated.
The main goal of this project was to establish field trials to compare Cabernet Sauvignon clones at the same site, to remove the confounding effects of climate, soil and management. In consultation with Wine Australia, three Geographical Indications were nominated for the establishment of the Cabernet Sauvignon clonal trials – these were Margaret River, Coonawarra and the Barossa Valley. The clonal composition was determined in consultation with the regional industry associations and with an aim to keep a strong similarity in the clones planted between the sites.
In Margaret River, the trial was established by chip budding into an existing Cabernet Sauvignon vineyard. The vineyard was top-worked in the spring of 2019, which accelerated the process relative to the other sites and allowed the cordons to be established within 12 months, and the first fruit to be harvested in 2021. In the Coonawarra and the Barossa Valley, the Cabernet Sauvignon clones were grafted onto 101-14 and planted in the spring of 2021. This delay was due to the discovery of virus in some of the clones of the vines that were propagated for the original planting date in spring 2019.
At the Coonawarra site, a randomised complete block trial design was used, with six vines per plot and 15 replicates. At the Barossa and Margaret River trial sites, a modified Latin square trial design was used, with three (Margaret River) or six (Barossa) vines per plot and 12-14 replicates. A high number of replicates was used across all the trial sites, as the differences between the clones were expected to be subtle and the extra replication would allow them to be quantified. For assessments that require high inputs, such as winemaking, the replicates can be easily pooled. The six vine replicates in the Barossa and Coonawarra also offer the potential to split the replicates in future to allow interactions between clone and other management practices to be investigated.
The three trial sites will provide a significant resource for the systematic assessment of the impact of Cabernet Sauvignon clones on vine performance and grape and wine style. This will potentially include the impact of climate change and how clone performance interacts with other management practices.
SARDI acknowledges the financial support from Wine Australia to complete this project and the companies in Coonawarra and Margaret River who kindly agreed to host the Cabernet Sauvignon clonal trials.