Want harder, healthier, tastier nuts? Ask these Adelaide researchers how...

Researchers at the University of Adelaide's Waite Campus know how much consumers love these go-to nuts. So they're working to develop more and better almonds. Self-fertilising, high-yielding, disease-resistant almond-tree varieties that produce nuts with harder shells, better taste and higher nutritional content – the first of which could be available to growers by as early as 2016.

Almond varieties that rely on pollinators are vulnerable to anything that threatens these species; hence the value of Michelle Wirthensohn's research.
Wiki Commons

Australia may be a major producer of almonds but the industry still has some hurdles to surmount: improving kernel quality and yield, boosting disease tolerance, and – arguably the most difficult – developing commercially viable, climate-tolerant almond trees with the capacity to self-fertilise.

With honeybee populations worldwide hit hard by CCD and varroa mite incursions, and Australia’s biosecurity under constant threat, developing self-pollinating almond varieties is a pressing priority.

Enter the Australian Almond Breeding (AB) program, the nation’s only such initiative, funded by Horticulture Innovation Australia Ltd (HIA) using the almond industry levy and funds from the Australian Government, and helmed by Dr Michelle Wirthensohn, a Horticulture Australia Research Fellow at University of Adelaide’s School of Agriculture, Food & Wine.

Wirthensohn and her team are looking to develop new almond varieties that are better suited to our climate and don’t rely on pollinators to produce.

“Australia is now the second-biggest producer of almonds in the world, with most being exported to India,” she says. “Our goal is to increase current production by 15 percent in the next five years and to decrease the reliance on existing cultivars over the next 10 years, to allow the industry to take advantage of this growing market.”

Currently, the best and most widely grown almond variety in Australia is the Nonpareil; unfortunately, however, Nonpareil trees need other varieties and bees for pollination.

“This means that up to half of the trees in some orchards are less productive and, potentially, decreasing bee populations could limit production even further, which places the industry at some risk,” Wirthensohn explains.

Australian commerical almond crops such as the one pictured currently rely entirely on external pollinators.
Almond Board of Australia (ABA)

By selectively crossbreeding local cultivars with the best French progeny of the Italian self-fertilising variety as well as Spanish and American cultivars over several years, Wirthensohn and her team of researchers have successfully bred the desired traits into experimental trees.

After numerous crossings, the AB program has tens of thousands of seedlings, about two thirds of which have been through the primary evaluation phase.

“We’re trying to develop high-yielding varieties: something that will out-yield Nonpareil by about 10 percent,” Wirthensohn says. “We’re looking at disease tolerance, so we’ve been doing some bacterial spot assays to detect who’s more tolerant than who – the Nonpareil variety is actually reasonably tolerant so we’re trying to get better than or as good as Nonpareil. We have several with good tolerance to bacterial spot.”

“We’re also looking for self-fertility: if varroa mite does come in and decimate Australian bee hives, then a self-fertilising tree will partly alleviate that problem.

“Of the ones we have evaluated,” Wirthensohn continues, “we’ve found many good ‘superior selections’. Those have then gone on to a tertiary phase of evaluation.”

Almonds growing on a test tree.
Michelle Wirthensohn, University of Adelaide

The project’s tertiary plantations, at three large trial sites in the almond-growing region along the Murray, are due to come into production in 2016. “With those, we’ll get a very high level of accuracy of determining their potential yield on the grower’s property,” says Wirthensohn.

“We expect to release up to five superior almond varieties by 2018. We will be commercialising five new varieties later this year, with PBR [plant breeder’s rights] and US Plant Patent applications being initiated now.

“Three of the five are self-fertile and all out-yield Nonpareil by up to 10 percent.”

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