There is merit in planting a range of Chardonnay or Shiraz clones within a vineyard and using the diversity between the clones to determine specific wine styles, a recently completed project has concluded.
The long-term research project – which evaluated a common selection of Chardonnay and Shiraz clones by assessing their viticultural performance and wine sensory properties in three climatically diverse regions of Australia – also found that location and season are just as important as clone to the end product.
Over the past decade, an increasing number of Chardonnay and Shiraz clones have been planted – in some instances with limited knowledge of their performance and impact on wine attributes.
This project, a collaboration between the South Australian Research and Development Institute (SARDI), Department of Agriculture and Food Western Australia, John Whiting Viticulture and the Australian Wine Research Institute (AWRI), was developed to evaluate grapevine clones through to winemaking and comprehensive sensory assessment.
Mature plantings of Shiraz and Chardonnay were selected in Victoria (Grampians and Drumborg), South Australia (Riverland and Barossa) and Western Australia (Margaret River and the Great Southern). The sites comprised a range of clones, some of which were common to all sites.
‘In choosing these sites we also sought diverse climates to test our hypothesis that differences in climate between sites could be used as a surrogate for climate change’, the research team said.
‘Our goal was to explore if the sensory attributes of a currently cool region could gradually become similar to those of a currently warm region and, similarly, would the profile of wines from a currently warm region become more like those of a currently hot region into the future?’
By assessing the fruit from common clones across multiple regions, the interaction between climatic conditions and clone could also be investigated.
Three consecutive seasons of vine performance and wine sensory data were collected from the four Shiraz sites, and four consecutive years of data from the five Chardonnay sites.
Wines were made using identical protocols and the wines then underwent sensory descriptive analysis each year by the same sensory panel.
The statistical analysis of the sensory data revealed significant differences in most attributes (approximately 30) between the wines made from different clones in each season.
Standard sensory descriptors were used in each of the three years for Shiraz to determine if there were any common descriptors for each region. The research found:
- Barossa wines were characterised as having dark fruit and sweet spice aroma and high opacity
- Grampians wines had consistent red fruit aroma, floral and confection
- Margaret River wines had consistent red fruit aroma, and
- Riverland wines showed considerable variation during the three years of the trial.
Results from the project have been presented at a range of regional wine tastings, both in the project regions and elsewhere.
Participants at each event have been asked to rank their preferences, based on their overall perception of the wines and their potential as finished commercial wines.
‘At most workshops, there was a most preferred clonal wine. Rankings of the same selection of wines tended to differ between regional groups.
Left to right: John Whiting, Richard Fennessy, Michael McCarthy, Liz Waters and Glynn Ward. (Libby Tassie, absent from photo)
‘Although the method was different from the descriptive analytical approach used by the AWRI sensory panel, both approaches demonstrate that there were clonal differences between the wines’, the research team concluded.
They said the knowledge generated by this project will enable grapegrowers and winemakers to select planting material best suited to their current conditions and intended wine style and that will reduce the impacts of future climatic changes.