Charles Sturt University
Charles Sturt University

Vine Physiology

The vine physiology team at the NWGIC researches factors that impact on berry composition and yield including extreme temperatures, water stress, plant nutrition and carbohydrate partitioning. It is also focused on defining sustainable and efficient vineyard management practises and developing automated systems for yield prediction.

Selected Research Projects

Improving industry capacity to manage the yield and wine quality relationship through understanding the influence of vine carbon balance on berry composition

Team leader: Bruno Holzapfel (NWGIC section)
Team members: Jason Smith, Julia Gouot, Celia Barril, David Foster (NWGIC section)

The experimental approach is to separate direct versus indirect effects of crop load and canopy size on berry composition. This is being achieved by implementing a range of canopy manipulation and crop load treatments applied to commercially grown Shiraz across three major regions. The second approach is to use container grown Shiraz vines and a CO2 scrubbing system to reduce photosynthesis during key stages of berry development. Fruit development and quality in both field and pot experiments is being assessed using traditional analyses of sugar, acids, colour and tannin content, but with the addition of a molecular approach that will target known genes involved in anthocyanin and tannin synthesis, and carbohydrate metabolism, allowing links between vine balance and berry composition to be established earlier than previously possible. These can then be used to establish markers for vine balance that can in turn be used to develop management strategies to achieve desired fruit quality within the season. The impact of the treatments on experimental wines made with fruit from both field and pot trials are also being assessed.

The influence of grapevine balance and water status during berry maturation on internal carbohydrate dynamics and leaf function

Team leader: Bruno Holzapfel
Team members: Gerhard Rossouw, Celia Barril, Alain Deloire, Jason Smith

Grapevine source-sink relationships induce various internal physiological interactions, resulting in variability of berry and canopy development. This is ultimately linked with alterations in grapevine carbohydrate reserve dynamics in grapevine perennial tissue, while leaf stomatal control will impact these interactions. The PhD project consists of experiments in potted vines to investigate the impact of vine water status and fruit-to-leaf ratios on internal reserve mobilization and assimilate production during maturation. The research showed water constraints during berry maturation could allow root starch remobilization, allowing reserve carbohydrate contribution to berry sugar accumulation, with the relative contribution potentially escalating in vines with lower leaf areas. This research will provide new perspectives about integrative physiological control of grapevines towards water use efficiency, grapevine balance and carbohydrate reserves, for improved performance and quality.

Evaluating and demonstrating new disease resistant varieties for warm irrigated areas

Team leader: Bruno Holzapfel (NWGIC section)
Team members: Alain Deloire, Suzy Rogiers, Jason Smith (NWGIC section)

The project is assessing the performance of 20 new varieties from the CSIRO breeding program, which are resistant to powdery mildew and show reduced susceptibility to downy mildew planted at the NWGIC. The varieties will be monitored for two growing seasons during establishment, and small scale vinifications and sensory analysis will be undertaken in the third year. The climatic conditions will be monitored, with consideration of some details on microclimate in the third season. In this season, the berry sugar accumulation will be monitored, together with amino acid accumulation. In addition, the fruit sensitivity to sunburn and heat stress will be assessed; vine water and nutrient status will also be monitored at key times. This assessment will determine the suitability and the adaptation of these varieties to warm irrigated regions. The project has recently been extended and now includes the establishment of 20 new disease resistant red varieties.