Tree survival signatures for drought-resilient fruit and nut trees

Optimising irrigation management for more drought-resilient orchards

Funded through the Australian Government’s Future Drought Fund, the $7.8 million, five-year Tree survival signatures for drought-resilient horticulture project aims to identify critical water stress thresholds in almond, pear and nectarine trees before long-term productivity is impacted. Researchers will establish ‘tree survival signatures’ – a response function that describes the relationship between water status and subsequent season productivity in fruit and nut crops.

By understanding these indicators, the project will develop practical irrigation decision-support tools and management guidelines to help growers:

Better prioritise water resources during drought
Be aware and make more informed irrigation decisions
Protect orchard long-term health and productivity
Improve tree recovery following drought
Build long-term orchard resilience.

Developing practical tools and management guidelines

The Victoria Drought Resilience Adoption & Innovation Hub (Vic Hub) brings together a consortium of project partners comprising of the University of Melbourne, Agriculture Victoria, Federation University and the Mallee Regional Innovation Centre to undertake the research and drive adoption of project outcomes across Victoria’s horticulture industry.

Over four growing seasons, the project will investigate how almond, pear and nectarine trees respond physiologically to water stress during drought. The research will also examine how de-fruiting influences tree survival, recovery and productivity, generating evidence needed to develop practical irrigation decision-support tools and management guidelines for growers.

Using an Airborne Subnanometer Hyperspectral Imaging Sensor, Australia’s only hyperspectral sensor of its kind, researchers from the University of Melbourne’s Hyperspectral and Thermal Remote Sensing Laboratory (HyperSens) will use aerial hyperspectral and thermal sensing, and in situ sensors to monitor tree water status across the orchard field experiments, providing detailed insights into tree water stress that underpin the development of tree survival signatures.

These aerial observations will be combined with robust field trials led by Agriculture Victoria at its Mildura and Tatura SmartFarms. Researchers will monitor a diverse range of orchard systems using dendrometers, micro-tensiometers, gauges and thermal imaging to measure the effects of severe irrigation deficits, rootstocks, de-branching and crop removal on water status and long-term yield. Demonstrations held at the SmartFarms will showcase practical drought management strategies relevant to regional growing conditions to support on-farm adoption.

Ensuing the project is practical for growers, Federation University's Centre for eResearch and Digital Innovation (CeDRI) will evaluate the decision-support tools to ensure they are accessible, practical and suitable for adoption by industry. Research findings will also be combined with grower knowledge and industry expertise provided by the Almond Board of Australia, Apple and Pear Australia Limited, Summerfruit Australia Limited, Fruit Growers Victoria and SuniTAFE, helping to ensure the research remains relevant to industry needs and priorities.

Together, this integrated approach will deliver a comprehensive study of drought resilience in perennial horticulture, equipping growers with the knowledge and practical tools to improve water management, protect orchard productivity and strengthen resilience to future droughts.

Project partners at Agriculture Victoria’s Mildura SmartFarm (March 2026) with a Green Atlas Cartographer, mapping tree performance of the orchard.

Project updates

2025/26

Results
During the first year of the project, researchers established experimental sites in mature pear, nectarine and almond orchards at the Tatura and Mildura SmartFarms to investigate how different irrigation, rootstock and canopy management strategies influence long-term tree responses to drought. Water status of these treatments was measured using ground-based instruments, aerial hyperspectral and thermal imaging, and in situ tree sensors to help identify critical water stress thresholds before long-term productivity is affected and informing the development of tree survival signatures.
The first season of water status measurements showed that there were only small effects of rootstocks, de-fruiting and de-branching on the development of water stress in the rainfed treatments. Almond trees responded more slowly to water stress than pears and nectarines, suggesting they may be better able to tolerate drought or access deeper soil moisture.
In situ sensors such as dendrometers and micro tensiometers clearly represented tree water status and will be considered as practical tools for growers to monitor tree water stress.
Early remote sensing results also closely matched on-ground measurements of tree water status. Canopy temperature and other plant health indicators successfully detected differences between irrigation treatments and rootstocks, demonstrating the potential for aerial monitoring to identify water stress before visible symptoms appear. These findings are supporting the development of practical irrigation decision-support tools for growers.
Next steps
In 2026/27, experimental plots from the previous season will return to full irrigation to monitor tree recovery and evaluate the effects of previous drought treatments on crop production, fruit quality and orchard performance. A new suite of experiments, including the timing of severe water deficits, will be established on different cultivars and rootstocks to further populate the relationship between water status and return productivity (i.e. a survival signature). Researchers will continue analysing the extensive field and remote sensing datasets to refine tree survival signatures and improve understanding of how difference species, rootstocks and management practices affect resilience during drought.
Data generated through the research will be combined with industry knowledge and grower experience to design demonstration sites that showcase practical drought management strategies and technology relevant to regional growing conditions.
Grower and industry engagement at industry events, workshops and field days will be undertaken to generate awareness of the project.

Maximising tree survival, productivity and faster orchard recovery

Periods of extreme water scarcity present significant challenges for Australia's $18.4 billion horticulture industry, requiring growers to balance limited water resources with the need to protect long-term orchard productivity.

During the Millennium Drought (1996-2010), Victoria’s annual catchment streamflow declined by 20-40%, resulting in reduced water allocations and escalating temporary water prices. These conditions forced many orchardists to make difficult decisions about where limited water resources could deliver the greatest return, while also weighing up the financial burden of purchasing temporary water.

As climate variability and future droughts continue to test the resilience of irrigated perennial tree crops, consultation with growers and water resource managers has identified the need for clear guidance and practical tools to inform water management decisions that maximise tree survival, minimise productivity losses and support faster orchard recovery.

Victoria is the largest producer of fruit and nuts in Australia, accounting for 33% of national production in 2021/22. The state’s diverse horticulture sector includes pome fruit, stone fruit, citrus and nut industries, making it well suited to investigating the impacts of water stress on perennial tree crops. The project focuses on stone fruit, pears and almonds, which are among Victoria’s major irrigated perennial horticulture commodities.

Acknowlgement

The Tree survival signatures for drought-resilient horticulture project is part of the Australian Government’s national Long-term Trials of Drought Resilient Farming Practices Program. The program aims to strengthen Australia’s agricultural resilience by testing innovative farming practices and generating the long-term evidence needed to support widespread adoption of drought-prepared farming systems.

The Tree survival signatures for drought-resilient horticulture project is funded through the Australian Government’s Future Drought Fund, led by University of Melbourne in partnership with the Victoria Drought Resilience Adoption & Innovation Hub (Vic Hub), Agriculture Victoria, Federation University and the Mallee Regional Innovation Centre to undertake the research and drive adoption of project outcomes across Victoria’s horticulture industry.