Smarter pear orchards

Published on November 8, 2023

Technology & Data

The experimental pear blocks at the Tatura SmartFarm and other commercial blocks have hosted important research to give growers the knowledge and tools to produce better quality pears. 

Key outcomes from the now complete PIPS3 Developing smarter and sustainable pear orchards to maximise fruit quality, yield and labour efficiency (AP19005) project were:  

• Reliable sensing technology is now available to measure pear orchard productivity. 
• New knowledge on red colour formation in blush pears. 
• Recommendations on orchard design and crop load to maximise productivity. 
• Hand thinning of pears increases fruit quality. 
• More efficient irrigation based on weather conditions and monitoring systems. 

Mobile sensing platform (Green Atlas Cartographer) 

Pear fruit size, fruit blush coverage and tree size (for example, canopy height and density, pruning mass) within an orchard block can now be measured with accuracy and precision. The technology processes optical images and light detection and ranging (LiDAR) data collected from cameras and a scanner mounted on a mobile platform, such as an ATV, that drives up and down orchard rows. Machine learning is used to detect fruit on the images and extract data on fruit diameter and fruit colour. As such, fruit can also be counted; however, some fruit will be obscured by foliage, so the fruit number per tree will not be as accurate as estimates of fruit size and colour. More accurate estimates of fruit number can be made by undertaking a block-specific calibration, although the raw data is sufficient to observe the relative variation across an orchard block. Similarly, flower clusters can be detected and counted, but calibration is required for the prediction of absolute numbers.  

The next phase of research in the PIPS 4 Profit Program will undertake an economic analysis of using the spatial data collected by the mobile sensing platform to implement zonal management strategies for flower and fruitlet thinning and colour development. Validation of the effects of zonal management of crop load (and colour, if suitable management options are forthcoming) versus uniform management will be undertaken in a commercial orchard. 

Red colour formation in blush pears 

Red colour in blush pears, such as ANP-0131 (marketed as Ricó™), is determined by light and is dynamic throughout the season. Sunlight will increase and shading will decrease the redness. Studies during PIPS3 showed that vigorous trees with lots of strong shoots created a dense canopy that resulted in fruit with less colour. Analysis of air temperature over several seasons in different experiments showed that heat events can halt or degrade colour synthesis although fruit can acclimatise. These findings suggest that maintaining good light distribution through the canopy is important so that colour forms and is stable throughout the season. In other words, don’t let vegetative growth get out of control in blush cultivars. 

Preliminary observations were also made on the effects of late-season reflective mulch. Foil was laid across the inter row in an Open Tatura trellis block of ANP-0131 approximately 2–3 weeks before harvest. There was no increase in red colour and the reflective mulch may have bleached fruit red colour and increased background yellow. 

The next phase pear project in the PIPS 4 Profit Program will focus on the timing of management intervention, alternative netting systems and new spray-on products to get better fruit colour and avoid sun damage. Smart evaporative cooling systems that operate in response to orchard conditions will be tested. 

Orchard design 

The effects of rootstocks, tree spacing and training systems in the experimental pear orchard at the Tatura SmartFarm continued to be monitored during PIPS3. Trees were in their eighth to tenth leaf. Our results showed that quince A and C are preferred rootstocks, with less vegetative vigour, higher and more consistent yields, and better fruit colour compared to BP1 and D6 rootstocks.  

Trees planted at high density (0.5–1m spacing) with 1- and 2-leaders produced more fruit and higher yields initially – 60 to 85 tonnes per ha in the fifth leaf – but then entered a biennial bearing pattern, whereas trees planted at lower density (2–3m tree spacing) with 6- and 8-leader cordon systems maintained moderate yields with less inter-seasonal fluctuation. Vase-trained trees produced the lowest 10-year cumulative yield, although yields in later years were similar to Open Tatura trellis and vertical leader systems. Fruit on Open Tatura trellis and vertical leader systems had higher colour coverage compared to 3D central leader training systems. 

Crop load and thinning 

Thinning should be considered in pears. Orchard-specific crop load management based on tree size (i.e. light interception) to target fruit size to maximise packout yield was investigated in PIPS3. Tree-scale data of fruit number, average fruit size and total light interception (a measure of the photosynthetic leaf area) from the experimental pear orchard at the Tatura SmartFarm was analysed. Relationships between crop load and fruit size were established so that an orchard-specific fruit number can be set for a targeted fruit size. 

Hand thinning of flower buds and the timing of fruitlet thinning was explored in a commercial block of ANP-0131. Initial results show that hand thinning of flower buds increased fruit size. Hand thinning fruitlets to 1–2 fruit per cluster increased colour intensity at harvest. The effects of these treatments on return bloom will be determined in the new PIPS 4 Profit project. In addition, mechanical thinning with a Darwin string thinner showed promising results and this will be further tested in PIPS 4 Profit. So far, chemical thinners have had no impact. 

Irrigation 

Pear growers can irrigate more efficiently based on weather conditions and monitoring systems. Results from previous PIPS projects were used to provide irrigation scheduling advice (www.hin.com.au/networks/blush-pear-research/irrigation-budgeting-and-seasonal-planning-tool-for-pear-growers). The emphasis is on using a spreadsheet template to plan monthly irrigation requirements and when to irrigate. An estimate of the fraction of the orchard shaded by the pear tree’s size is the only input required. During the season, feedback from soil moisture and plant-based sensors to adjust the irrigation schedule – particularly at the start of the season and after rain – is recommended. The new PIPS 4 Profit pear project aims to remotely monitor irrigation efficiency in pear orchard blocks. 

Further information 

Visit the PIPS3 Program’s Developing smarter and sustainable pear orchards to maximise fruit quality, yield and labour efficiency (AP19005) project webpage: https://apal.org.au/programs/more-industry-programs/pips3program/ap19005/ 

Articles 

Barber A (2022) “Raising the bar: Light, colour and the role of temperature in blush pears”, Australian Fruitgrower 16(1):35–37.  

Bound S (2023) “Understanding crop load in European pears”, Australian Fruitgrower 17(2):48–51. 

McClymont L, Goodwin I (2021), “Optimising ‘climate-smart pear’ relationships”, Australian Fruitgrower 15(1):42–43.  

McClymont L, Goodwin I (2021) “Growing high-density blush pears on Quince A rootstock”, Australian Fruitgrower 15(3):56–58. 

Scalisi A, McClymont L, Goodwin I (2021) “Cartographer maps path to uniform, high quality pears”, Australian Fruitgrower 15(4):46–47. 

Scalisi A, McClymont L, Goodwin I (2022) “Orchard estimates of blush coverage in pears”, Australian Fruitgrower 16(4):37–39. 

Singh R, Peavey M, McClymont L (2023) “Effect of high temperatures on red colour development in blush pears”, Australian Fruitgrower 17(1):35–37.  

Videos 

“Artificial heating and cooling”, www.youtube.com/watch?v=uuCvcttspkQ  

“Sensing technologies to improve predictions and management of crop load”, www.youtube.com/watch?v=NCeIW7SAjbQ&t=5s 

“Planting systems”, www.youtube.com/watch?v=9NK0GKTxBUE 

Acknowledgements 

The PIPS3 Program’s Developing smarter and sustainable pear orchards to maximise fruit quality, yield and labour efficiency (AP19005) project and upcoming PIPS 4 Profit Program’s Pear production systems (AP22002) project are funded by Hort Innovation, using the apple and pear research and development levy, contributions from the Australian Government and co-investment from Agriculture Victoria. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture. 

This article was first published in the Spring 2023 edition of AFG.

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