RESEARCH & EVENTS
Orchard intensification: research outcomes are paving the way to high density viability
This project was carried out through a partnership between the New Zealand Institute for Plant and Food Research Limited( PFR) and the South Australian Research and Development Institute( SARDI).
PFR team: Roberta De Bei, Grant Thorp, Jill Stanley and Ken Breen. SARDI team: Tim Pitt, Kavitha Shanmugam, Darren Graetz and Paul Petrie.
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WITH the right genetics and tailored management, intensification has potential to significantly increase yields and early orchard profitability. Demonstrated sustained economic viability remains a critical long-term research objective. The last decade has witnessed Australian almonds become the nation’ s most valuable exported horticultural crop. Yet, reliance on traditional, low-density orchards, with large trees that often result in poor light distribution and potentially inefficient use of resources, have kept yields stable. In 2020, Hort Innovation funded the“ National tree crop intensification in Horticulture”( AS18000) program, a multi-crop( including almonds) and multi-agency R & D investment aimed to boost productivity and profitability through improvements in orchard systems intensification. High density( HD) is a system where trees( and rows) are planted much closer together than in traditional orchards with the aim of maximising yield per unit of land, improving input efficiencies and facilitating mechanization. There is not established consensus on the number of trees per hectare that defines HD however, for densities above 1500-2000 trees / ha the term Super High Density( SHD) is used. The almond component of the AS18000 program explored intensive planting systems, assessed cultivars and rootstocks new to Australia and specifically chosen for their suitability in high-density orchards, and pioneered new pruning and training methods. The scale of the evaluation involved over twenty scion cultivars and nine rootstocks tested across a wide spectrum of planting densities,
In A Nutshell- Spring 2025 Vol 26 Issue 3
Shasta ® grafted on Controller TM 6. The photo was taken at harvest 2025( February 2025). To note the small size and open canopy of these seventh-leaf trees. The 4.5m row is still fully accessible with narrow machinery.
ranging from conventional 350 trees / ha to 1,481 trees / ha. What did we learn? 1. Planting material Central axis trees offer an alternative to traditional headed trees with the advantage of more uniform branching that reduces susceptibility to wind breakage. 2. Scions, rootstocks and their combinations Scions with compact and open canopies, precocious spur habits and uniform maturation, combined with dwarfing rootstocks are essential for orchard intensification. Incorporating these architectural traits as breeding targets will be key to advancing future orchard systems.
3. Tree architecture Cultivars that are well-suited for higher density or two-dimensional( 2D) orchard systems possess specific architectural characteristics: a narrow canopy shape, a porous, open canopy, a limited number of upright scaffold branches, and a combination of short and medium shoots. 4. Pruning and hedging High-density orchards require specific pruning and hedging to ensure longterm productivity and canopy control. Pruning inspired by the Spanish“ Poda Aragonesa” improved the internal canopy light environment and showed potential for improved longterm productive canopy volume.
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