Under-vine management effects on grapevine production, soil properties and plant communities in South Australia

Merlot grapevine is the second wine cultivar most planted in the world and especially in the Bordeaux wine region. This cultivar has many advantages in producing high quality wine; however, in the last decade, climate change has increased the sugar concentration in berries at harvest and shortened the maturation cycle. If this has been up to now a great opportunity to improve wine quality profile, we are touching the tipping point. High sugar concentration at harvest induces high alcool content in wine which can negatively impact wine quality. There are many viticultural and oenological practices possible to limit this effect. In this study we focus on plant material through intra-varietal diversity of Merlot cultivar.

Grapevine grafting is a complex process that since the establishment of phylloxera has become mandatory for grapevine. Grafting success in grapevine nurseries considerably varies among years and batches with most variety/rootstock combinations reach a high success rate (between 75% and 90%), but some combinations show lower success rates of around 40-50%. The causes of this variation are unknown, although biotic stresses like those caused by some viral infections have been demonstrated to affect the process. European certification schemes for the vegetative propagation of the vine include five major viruses (Arabis mosaic virus, Grapevine Fanleaf Virus, Grapevine Fleck Virus, and Grapevine-associated Leafroll Virus 1 and 3).

Consumers predominantly use visual, aromatic and texture cues as quality/preference indicators to describe olfactory sensations. In this study, the effect of micro-organism in wine production was investigated using analytical and sensory techniques to achieve relevant analytical characterisation. Selected anthocyanins, flavan-3-ols, flavonols and phenolic acids were quantified in Syrah wines using RP-HPLC-DAD. Standard oenological parameters were also measured. Syrah grape must was fermented with various combinations of Saccharomyces cerevisiae (S. cerevisiae) and non-Saccharomyces (Metschnikowia pulcherrima or Hanseniaspora uvarum) yeasts, which was followed by sequential inoculation of lactic acid bacteria (LAB) (Oenococcus oeni or Lactobacillus plantarum).

Colour is an important quality parameter in wines and is the result of a complex mixture of pigments
(including anthocyanins and their derivatives, quinones, xanthyllium compounds, etc.). Red wine colour changes over time as pigments react between themselves and with other wine macromolecules
(particularly polyphenols). During wine tasting, colour is normally assessed on the outer rim of the wine profile in a tilted glass, since most wines are too opaque to be analysed in the middle of the glass. Therefore, depending on the depth of observation considered, the perception of wine colour can be different.

The research includes an analysis of the impact of weather conditions on phenological development of the vine and grape quality, through monitoring of four experimental cultivars (Chardonnay, Graševina, Merlot and Plavac mali) over two production years. In each experimental vineyard, which were evenly distributed throughout the regions of Slavonia and The Croatian Danube, Croatian Uplands,