Science comes to the rescue to help identify apple tree varieties in an Otago heritage orchard.
The lines of apple trees look lush and healthy, some garlanded with a heavy crop of coloured orbs - greens, bright reds, yellow-striped.
For some, the variety is apparent even on the same tree, hosting, as these trees are, two to three different apple cultivars.
And keeping this variety alive is the whole point of this Otago orchard.
The Jim Dunckley Heritage Orchard
Ann Dunckley remembers her dad stopping to look at apple trees at the side of the road or in old orchards when they were out and about.
"He liked apples," she says, "and he was worried about the fact that the old ones were disappearing, old farm orchards were being bulldozed."
Jim was a founding member of the Coastal Otago Branch of the New Zealand Tree Crops Association and, along with friend Paul Snyder, started collecting different varieties of apple trees in the 1990s.
Unfortunately, Jim has died but the orchard lives on, having moved to a site near Mount Cargill, just outside of Dunedin city, in the early 2000s.
The idea is that the orchard acts like a living library. New growth or scion wood can be harvested off these trees, stored over winter and then grafted on to new root stock trees to replicate the cultivar.
However, across time, notes and labels were misplaced and uncertainty about the varieties crept in.
It was a chance encounter on an orchard open day that would provide the solution.
Science to the rescue
It was their first orchard open day in 2023 that kicked it all off, says Donal Ferguson, who until recently was chair of the Coastal Otago Branch of the New Zealand Tree Crops Association.
Associate Professor Lynette Brownfield from the University of Otago's Biochemistry department came along, and when she learned about the identification problem she offered up a solution - genetic testing.
Masters student Aaron Hewson was given the task. Starting with 336 leaf samples, he used genetic analysis to compare the varieties in the orchard to those in the Bioeconomy Science Institute's heritage orchard records. Some of them matched genetically, but were labelled differently, so he was forced to go further afield.
Luckily, there has been a lot of work overseas looking into heritage apples, including compiling genetic and physical trait databases.
To the team's surprise, 80% of the samples matched with apple tree cultivars in this database and some of them were duplicates.
The remaining 20% are likely seedlings, Hewson said.
While grafting an apple tree creates a clone that is genetically identical, it is quite different if you grow a tree from seed, he explained.
"They're quite a genetically diverse species. So, if you cross any two apples together and get a seed, it's going to look very different to the parents. It's going to be a random mix up."
It's a bit trickier to identify seedlings then, because that means working backwards to figure out a 'family tree' for the apple that traces back to the varieties in the database.
But these seedlings might also represent the interesting variety that the orchard was aiming to conserve - apples with desirable traits that grow well in coastal Otago conditions.
It's these traits that Hewson finds interesting to think about. For commercial growing, breeders are focused on characteristics like storage, resistance to bruising and disease, or a certain colour or crispness.
But this orchard contains a much wider variety of colour, texture and flavours than can be found in our supermarket apples.
Now, thanks to the research, these varieties can be confidently shared with whoever might want to grow them.
