Getting a taste for dry climate wines

If Peter Clingeleffer ran a restaurant, it would have a pretty daunting wine list.

Over the past six years he has commissioned small batches of wine from more than 150 different varieties that are not currently planted – let alone made into wine – in Australia to see which have the greatest potential to help the sector with the practical implications of climate change.

Of these he has nominated 6 whites and 11 reds (3 specifically for lighter-style wines) in his final report to Wine Australia on a major study investigating enhanced grapevine varieties and clones. All have been doubly tested – scientifically by Peter and his colleagues at the CSIRO and in the glass by winemakers and others at a series of tastings.

These are varieties that not only could survive and thrive in warmer conditions, but also have commercial potential either as wine styles in their own right or to blend with more commonly made styles.

The wines initially were made by the CSIRO at its Merbein research station and then by the Victorian Department of Economic Development, Jobs, Transport and Resources, which took over the winemaking capability when the CSIRO site was closed.

‘It was important to get feedback on what the wines actually tasted like and whether they had genuine potential, and the response has generally been pretty positive’, Peter said.

‘We do acid addition to adjust pH but they never see oak and we don’t do malolactic fermentation, so what you are really seeing is straight fruit-driven characteristics.’

However, these 17 wines are just the tip of the iceberg.

The project assessed 566 different varieties plus more than 300 clones, creating a comprehensive and detailed database that Peter hopes will soon be made accessible to the Australian grape and wine community.

The aim was to uncover traits that might be important for climate change and the original three-year project was extended to six, allowing two rounds of testing over four seasons in vineyards in the Sunraysia area; first, older vines established at CSIRO Merbein and secondly, younger vines planted at the CSIRO Irymple farm site.

The study, which was funded by Wine Australia, also tested for varieties that offer the potential to produce lower alcohol wines.

Each of the individual varieties, clones and selections was studied in exactly the same way, with particular attention paid to vine phenology (including the timing of budburst, flowering, veraison and harvest) and the measurement of key growth characteristics and berry composition.

The study has identified varieties grown under hot conditions with:

• short seasonality, to improve water-use efficiency in hot irrigated regions and diversify the production base in cooler regions
• smaller canopies, to minimise transpiration, improve water-use efficiency and improve production efficiencies, if used in high-density plantings
• long seasonality, to ripen in cooler conditions and extend the season
• optimal pH and titratable acidity levels, which may enable crops to be harvested at lower maturity to produce lower alcohol wines
• improved composition (pH, organic acids, colour) and wine flavour and aroma, which may provide opportunities for marketing at higher price points.

Peter said there was great interest in the potential to extend the season given the increasing problem of compressed vintages.

From a scientific perspective, it was the incredible contrasts between varieties, clones and selections that really surprised.

The researchers reported 2-fold differences in seasonality, 5-fold differences in fruitfulness, 10-fold differences in berry mineral ion concentrations, and 15-fold differences in berry weight.

‘These are very big differences for plants growing side by side, all on their own roots, and under exactly the same conditions’, Peter said. ‘It’s amazing.’

From here, he believes, there is great potential to get down to the genetic level and actually identify how and why this is the case. ‘It opens up a lot of things to do; I wish I was young again’, he said.

The final report of the project, which makes 11 recommendations, can be accessed on the Wine Australia website here.