Profitable Stonefruit Research

Researchers at the Tatura SmartFarm experimental stonefruit orchard are looking at drought recovery responses of a nectarine orchard by using full irrigation following long-term deficit water management

  • September Bright nectarine trees with Elbert rootstock planted in 2014 on Open Tatura, 2222 trees/ha
  • Determine recovery of trees from deficit irrigation since 2016
  • Drought recovery responses measured during 2022/23 season under full irrigation for optimal marketable yield using world leading, cutting edge technologies

Senior Research Scientist: Dr Mark O'Connell, Agriculture Victoria Research

Video: Stonefruit drought recovery study on deficit irrigated nectarine trees

Dr Mark O'Connell discusses drought recovery responses of a nectarine orchard by using full irrigation following long-term deficit water management
Video Transcript

I am standing in an experimental orchard, a stone fruit orchard today, and we've been conducting a study on drought recovery responses to deficit irrigation. And what we're looking at is those responses of the historical deficits, whether that is there any recovery or not in the full irrigated year, this current season.

Yeah, and it's important because the information on drought recovery and productivity and fruit quality and yield is limiting on stone fruit. So, what we've been doing is fully, as I said, fully irrigating these trees this year and doing scans with a cartographer, a mobile sensing platform. And that platform's allowing us to scan the trees, look at tree size, canopies, and also focus on the individual fruit, look at fruit growth, fruit size, fruit colour and yield. So we've done scans right through stage two and stage three of the fruit growing season. These fruit will be harvested in another couple of weeks, at the end of February. It's a September Bright nectarine cultivar, and harvest time is around the end of February, start of March.

We're collecting the data across the season and using mobile platform technology and artificial intelligence and the latest sensing technologies to scan these trees, look at the responses from the historical deficit irrigation treatments.

So, I'm standing beside the Green Atlas photographer. This is our mobile platform to sense tree and fruit metrics. It's on an ATV. This one's actually an electric vehicle. But the sensors are all based at the back here. We have strobe lights, RGB high resolution cameras, LiDAR, the infrared temperature sensors, and obviously the GPS. So, all these sensors are working at high speed, multiple times per second as you scan up and down the orchard row to collect that crop and tree information.

Some of the measurements we're taking with the cartographer are looking at the fruit and looking at the canopy. So, for example, fruit size is important, fruit colour, the number of fruit on each tree, the total canopy, leaf area, and tree size. So, these metrics are being used to indicate the productivity and the response to deficit irrigation.

On top of that, we're sensing tree stress through thermal indices, so we are measuring canopy temperature with an infrared technology, sensors, and we can calculate crop water stress index, which is an index of water stress and canopy temperature, obviously. So, we're using all these metrics, production metrics, tree size metrics, fruit quality metrics and crop stress metrics to give us a performance of each individual treatment and tree, compare the historical deficit irrigation to the current season, full irrigation, in looking at that drought recovery response.

So far, the orchard scans with the cartographer has shown that in terms of water stress, the crop water stress index and the canopy temperature information, is there's no difference between treatments, historical deficit, irrigation treatment. So that means our crop water requirements being met this year, and the trees are matching crop water requirement with irrigation supply. However, we are showing reduced fruit size and potentially lower yields, which we haven't finished harvesting yet, so until we come to maturity will confirm that with the cartographer. So, the historic deficit irrigated trees at, it’s at high levels of deficit, like 20% crop water requirement, historically haven't recovered and their fruit size is lower, which is a good finding. The RDI strategy historically where we've irrigated at 40% during the stage two of fruit growth historically has shown no effects of fruit size this season. So that means that strategy works and there's no long-term carryover effects. So, we're getting some drought recovery responses and the final scan at harvest time in a couple of weeks will confirm yield and fruits, final fruit size and also final fruit colour differences if they're there.

Results after full irrigation:

  • RDI (regulated deficit irrigation) regimes practiced during fruit growth stage II provide water savings, improved water use efficiency and maintain sustainable yield and fruit quality production outcomes.
  • Severe deficit irrigation regimes suffer sustained reduced cropping levels (fruit number) and reduced tree health and vigour (tree height, canopy leaf area)
Tree size, canopy water stress, fruit size, fruit colour and yield were measured to determine the level of recovery from long-term  deficit irrigation of 0% (extreme deficit), 20% (severe deficit) and 40% (moderate deficit) of crop water requirement during stages 1, 2 and 3 of fruit growth (graph 1).
Shoot & Fruit Growth graph Graph 1 - shoot and fruit growth

Graph indicating percentage of growth during stage 1, 2 and 3 of shoot and fruit development during the production season.

Latest technologies measure orchard recovery

A ground-based sensing platform was used for fast assessment of key horticultural and physiological information.

Data measurements were captured with a cartographer (mobile platform technology), using the latest sensing technologies and artificial intelligence.

The GreenAtlas CartographerTM uses sensors such as LiDAR, Infrared and high resolution RGB cameras, and a GPS along with artificial intelligence to determine:

  • fruit size
  • fruit colour
  • fruit number
  • yield
  • tree size
  • canopy temperature
Green Atlas Cartographer Image 1: GreenAtlas Cartographer

The data captured from these metrics on production, tree size, fruit quality and crop stress informed the level of recovery of each tree from their historical deficit irrigation treatment when using a full irrigation treatment.

GreenAtlas cartographerTM(image 1): ground-based sensing platform for fast assessment of key horticultural and physiological information.

  • This technology can be used by producers to estimates yield prior to harvest, determine fruit quality and fruit maturity, and monitor plant water stress.

Mobile sensing in orchards

Project acknowledgement

This research (SF17006 Summerfruit Orchard Phase 2) was funded by Agriculture Victoria with co-investment from Horticulture Innovation Australia Limited using the Summerfruit levy and funds from the Australian Government.

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