Vine balance focus of new multi-region trials

The University of Adelaide and the CSIRO with the National Wine and Grape Industry Centre will begin collating data this vintage from two separate but collaborative projects investigating the methods and technology used to achieve vine balance.

Both projects will run separately, but come under a joint GWRDC-funded vine balance research initiative, share an Industry Reference Group and will assist each other with some joint trial work.

Vine balance toolbox

The University of Adelaide-based project, led by Cassandra Collins, will evaluate whether measures of vine balance and canopy density correlate with grape and wine quality using modelling and meta-analysis of previous benchmarking studies and current experimental trials. The project also aims to develop a vine balance ‘toolbox’ for industry to ensure best practice, sustainability and profitability.

The project will run in collaboration with University of Melbourne and Treasury Wine Estates, with the majority of the results to be taken from Shiraz vines from trial sites in the Barossa, McLaren Vale and Padthaway, as well as one Cabernet Sauvignon trial in the Coonawarra.

‘To assess vine balance, traditional measures (e.g. yield, pruning weight, canopy density) will be compared to new technologies using imaging and smartphone Apps to determine if new technologies are more accurate, easy to use and less expensive’, Dr Collins said.

‘Small lot wines will also be made from some of the trials to investigate the relationship between vine balance measures and wine quality’.

This will be the trial’s first vintage, Dr Collins said, with seasonal and regional variability considered a bonus for the project.

‘Part of the project will be to build a history of the sites being investigated and seasonal variation will play an important part in understanding the performance of each vineyard’, she said.

‘In fact, the more variation in the seasons the better as this will give us a better idea of what measures really are true indicators of vine balance and whether or not these correlate with wine quality’.

A challenge already identified, however, will be determining how well some of the new technologies perform when different cultivars and training systems are used in the vineyard, Dr Collins said.

‘To overcome this we will be beta testing these technologies at a number of different indicator sites where different cultivars and training systems are being used’.

Vine balance and carbon relationship
The joint CSIRO and NWGIC project is seeking to improve industry capacity to manage the yield and wine quality relationship through understanding the influence of vine carbon balance on berry composition.

Led by CSIRO research scientist Everard Edwards with Jason Smith of the NWGIC, the project will use three vineyard sites, in NSW, Victoria and South Australia, across three vintages and has already started implementing the different canopy management treatments.

‘To manipulate the relationship between canopy and crop load we will be using, early defoliation (to reduce fruit-set), fruit thinning (approx. 50%, shortly before veraison), and late defoliation (also shortly before veraison)’, Dr Edwards said.

‘While these treatments could be considered management trials in their own right, our primary intention is to alter vine balance in order to study changes in gene expression in the fruit and match them with changes in fruit composition.

‘In addition, work at the NWGIC is about to start utilising chambers on potted fruiting vines to reduce photosynthesis (via low CO2 concentrations in the air). This will simulate defoliation without altering the light environment on the bunch and the fruit will be processed in the same way as the fruit from the field.’

Though still early days, the first hurdle Dr Edwards said has been the amount of site work needed to undertake one of the treatments.

‘Though we expected it, undertaking the early leaf removal by hand on vigorous warm climate vines, is a lot of work!  If the treatment shows any success we will be finding a mechanical way of completing it next season’, he said.