Evaluation of potential prunus rootstocks for almond production – stage 2 (AL16006)
What’s it all about?
Beginning in February 2018, this project carries on from earlier industry work to evaluate a range of potential new almond rootstocks – assessing their compatibility with the common almond cultivars grown in Australia, and their performance under the country’s various growing conditions.
The earlier work saw 14 rootstocks, including Nemaguard, planted for evaluation at a trial site in Lindsay Point, Victoria. The current project is continuing these evaluations and building upon the research, including through the introduction of new technologies and the establishment of further trials.
The researchers report that they have completed their yearly data collection and have ordered rootstock trees for the next stage of the project.
Winter tree measurements
Trunk circumference measures were made to track growth across the different varieties. Trends so far suggest that Carmel grows at a slower rate than the other varieties. Measurements were also made of the Nonpareil sample trees with height and width recorded and canopy area estimated from above using an unmanned aerial vehical (UAV).
Harvest yield analysis
Yield was measured showing an average 2.25 tonnes per hectare, but with variability of up to 790kg from different rootstocks. The yield and tree dimension data allowed calculation of canopy efficiency which will be updated in subsequent years.
Laboratory analysis of elements
Leaf and soil nutrition were analysed with researchers noting levels of elements from the samples.
Flowering dates were collected, showing a five-day range across the rootstocks. Tree anchorage was measured, and fungal pathogens monitored. Nematode sampling was also conducted showing a very small number of nematodes present.
Tree habit was measured using a LIDAR to assess tree canopy and density. Canopy temperature was used to measure tree stress and was recorded with UAV infra-red technology showing a consistent relationship between the light interception results and canopy temperature. Larger canopies were also found to produce a lower canopy temperature.
The project team report that data collection is ongoing at the Lindsay Point trial site, with information being collected on rootstock/scion compatibility, tree vigour, yields and susceptibility to nematodes.
Flowering phenology observations, which involve closely monitoring flowering across the site for a six-week period during August and early September, will soon begin. The researchers note that assessing the impact of different rootstock/scion combinations on bloom dates is critical in the choice of the mix of varieties to plant. As almonds are totally pollination dependent, the synchronicity of flowering times with Nonpareil, the major industry variety, is critical in designing orchard plantings.
Information from the trial is being conveyed to growers at field days conducted on site – look for future events to be advertised in industry channels.
In addition to the Lindsay Point work, the project has another trial at Loxton to evaluate prunus rootstocks in heavier soil types, as well as a further site within the experimental orchard at the National Almond Centre of Excellence, also in Loxton, to evaluate a host of rootstocks and their performance in lighter soils.
This project is a strategic levy investment in the Hort Innovation Almond Fund