Innovative rootstocks for the Australian macadamia industry (MC16000)
What’s it all about?
This investment is analysing and identifying rootstock genotypes that offer the best prospects for productivity improvements in the Australian macadamia industry. Over 2000 mature trees utilising some 200 rootstocks are bring assessed under commercial orchard management conditions, with productivity and quality assessments compared to those of current industry rootstocks Beaumont and H2.
The research team reports that they have completed the 2018 measurements including nut yield, tree size, canopy density and any symptoms of abnormal vertical growth.
Nut yield was measured during five nut-drop periods, the first of which occurred far earlier than expected. Production from the orchard was excellent, reflecting the high level of management expertise that is being brought to this commercial orchard.
As a small number of interesting rootstocks start to emerge, the research team made checks of kernel quality, but found all were of excellent quality. Yield is therefore a central focus for the project from here on.
Now that the trees have reached maturity, with hedging and skirting for the last three seasons, it is anticipated that the 2019 season will provide sufficient data to be able to make suggestions about which rootstocks warrant commercial testing and which should be avoided.
Assessments were made throughout the 2017 season, and will ultimately be used with other seasons of data to provide a full picture of rootstock influence on macadamia performance. Information is being collected from more than 660 plots includes nut yield, tree size, canopy density and any symptoms of abnormal vertical growth (AVG) – though it will only be through the collation and analysis of data from multiple seasons that project results will be known.
For 2017, the researchers report that nut yield estimates made prior to each commercial harvest strongly correlated with actual nut production, and that tree health has remained strong – though early signs of AVG have been observed in some trees, in a specific section of the orchard, and is being monitored. The researchers note that this is an important research finding, and creates an opportunity to monitor development of the disorder as part of the project. AVG is normally associated with a dramatic decline in nut production, so the early detection of potential AVG trees creates an opportunity to study any changes in nut yield using the data already being generated in this project.
The team also report that been demonstrated for the assessment of commercially important traits in a large mature rootstock experiment managed under commercial conditions. This will now be applied to examine any rootstock influence on tree performance in the critical period after canopy closure, and as canopy management inputs become more frequent and severe in order to maintain machinery access. Early signs of the disorder Abnormal Vertical Growth have been detected creating a unique opportunity to study impact on productivity from an early stage.
This project is a strategic levy investment in the Hort Innovation Macadamia Fund