Data driven irrigation scheduling to reduce irrigation requirements in an Australian cool climate ‘Cabernet Sauvignon’ vineyard

As part of my PhD at the University of Adelaide in South Australia, my research has largely focused on vineyard irrigation management and vine physiology. I have a special interest in optimising irrigation scheduling to improve water use efficiency (WUE) for winegrapes, particularly with the use of plant sensors. Irrigation scheduling strategies can be broadly described by four main categories: approaches based on historical applications/personal experience (typically non-data driven), evapotranspiration (i.e. crop evapotranspiration, ETc, data-driven approach), and plant and soil water sensing (data driven approaches). However, there is no consensus on the ideal scheduling strategy to improve WUE. To investigate optimisation of vineyard irrigation scheduling, an irrigation trial was carried out in a premium ‘Cabernet Sauvignon’ vineyard located in the Coonawarra region of South Australia. Conventional means of irrigation scheduling (i.e. based on experience/historical knowledge) were compared alongside data-driven approaches in order to improve WUE. Over three growing seasons (2018/2019, 2019/2020 and 2020/2021), leaf gas exchange, vine water potential, and light interception were measured throughout the growing season, and yield components and pruning weight were determined following harvest, in addition to an analysis of berry composition. WUE metrics were also calculated using leaf, vine and fruit scales (intrinsic WUE, WUEi), crop yield (WUEc), and carbon isotope ratio (δ13C). Compared to conventional approaches, irrigation scheduling following measurements of ETc and the use of plant water status thresholds resulted in irrigation reductions of up to 60%. This was associated with small improvements to WUEc, in addition to WUEi and δ13C metrics. Despite the large reduction in water, there were no significant differences in berry composition between treatments, indicating that data-driven treatments could achieve a similar berry quality to standard grower practices for this premium vineyard. Overall, the data from this study suggest that data-driven irrigation scheduling is recommended over non data-driven approaches.

Rochelle Schlank won the ISHS Young Minds Award for the best poster presentation at the X International Symposium on Irrigation of Horticultural Crops in South Africa in January-February 2023.

Rochelle Schlank, School of Agriculture, Food and Wine, The University of Adelaide, Waite Research Institute, PMB 1, Glen Osmond, SA 5064, Australia, e-mail: rochelle.schlank@adelaide.edu.au

The article is available in Chronica Horticulturae