When you next sip on a locally grown single-origin Arabica coffee, the variety of tree it is sourced from might not matter to you, but it does to growers.

Key points:

  • Researchers are trialling 25 coffee varieties from across the world in the Australian environment
  • Growers have narrowed down their favourites to four from Brazil, Mexico, Honduras and France
  • COVID delays tasting panels in project underway to define terroir of Australian coffee to increase its demand

Australian coffee farmers want high quality, high yielding, and disease-resistant tree traits the K7 variety has delivered on for some two decades, but now growers want all that and less. Less of tree size, that is. 

Whilst the K7 has performed extremely well in terms of all those attributes, its excessive vigour, initially welcomed 20 years ago, threatens the industry’s viability.

Researchers at Southern Cross Plant Science, backed by AgriFutures Emerging Industries, is working with the Australian Sub Tropical Coffee Association to find new varieties trialling 25 from around the world.

Terry Rose and Tobias Kretzschmar with a coffee tree.

Professor Terry Rose and Associate Professor Tobias Kretzschmar, from Southern Cross Plant Science, with one of the coffee varieties being trialled as part of an AgriFutures funded project.(ABC Rural: Kim Honan)

Associate Professor Dr Tobias Kretzschmar said their coffee varietal project was part of an international multi-variety trial.

“That means the same varieties at the same set up are being trialled at 17 countries across the world, which will allow us to pull the data together later on and see which varieties perform across different environments,” he said.

The main attribute that growers are looking for is a dwarf or semi-dwarf variety to eliminate the need for pruning.

Professor Dr Terry Rose said the K7 was too vigorous, particularly in the Northern Rivers’ red volcanic soils, and grew too high for machine harvesting.

“The bush puts a lot of energy into growing new shoots rather than putting it into beans, so what we really need is a dwarf variety that will grow to about the right height for the harvesters and then just focus on producing beans and not excess shoots.”

Southern Cross University Associate Professor Tobias Kretzschmar with growers on the coffee research trial plot.

Southern Cross Plant Science Associate professor Tobias Kretzschmar with local growers at the coffee varietal trial research plot at Alstonville near Lismore. (ABC Rural: Kim Honan)

When the project started in 2017 sourcing germplasm internationally, due to Australia’s tough biosecurity standards, the researchers were only able to import tissue culture clones that were kept under strict quarantine conditions.

While the first of the cherries have just been picked from imported varieties planted in 2019, it could be at least a decade before consumers get a taste.

Rebecca Zentveld picks a coffee cherry.

Rebecca Zentveld picks a coffee cherry on the Southern Cross University coffee varietal trial plot at Alstonville.(ABC Rural: Kim Honan)

Sub-tropical coffee growers have narrowed their preferred varieties to four from Brazil, Mexico, Honduras and France. However, another four years remain of the trial, which researchers also plan to replicate in far north Queensland.

K7 still the pick of the crop, for now

Kahawa Estate Coffee in the Byron hinterland is in a renewal stage. Jos Webber’s pulled out 3,000 trees – with a crop or two left on the remaining trees — and will replace them with 2,000 K7 seedlings.

“Hopefully, we can manage them a little bit differently with the pruning and gradually rotate the K7 out of the plantation as we put these new varieties in,” he said.

Jos Webber holding a tray of coffee seedlings.

Grower Jos Webber holding a tray of coffee K7 seedlings on his farm at Teven in the Northern Rivers.(ABC Rural: Kim Honan)

With two years of harvest lost every pruning cycle, Mr Webber said the future was in the new varieties, which would not only be more productive but would protect the local coffee industry from coffee least rust.

“We in Australia are unique in that we don’t have coffee leaf rust, so we really want to keep that out, but it’s inevitable that it will come in and so if we’ve got a variety growing that is resistant to coffee leaf rust than our industry isn’t as exposed,” he said.

Defining the terroir of Australian coffee

Terroir is a French term often used in the wine industry to describe the environmental factors — soil, climate, elevation —  that affect the taste, but now researchers at Southern Cross University have set out to define the terroir of Australian coffee.

“Traditionally, coffee is assessed on a score-based system, which is a good way for people to assess the quality, but it doesn’t really describe the flavour,” Dr Simon Williams said

Coffee beans being poured into a white cup from a paper bag.

Pouring roasted coffee beans into a cup at the tasting panel.(Supplied: Ben Liu)

The three-year AgriFutures project compares the coffee grown in sub-tropical Australia with coffee grown in far north Queensland and international coffee to determine the taste difference and develop a local flavour profile.

“Based on a review we’ve done looking at the different literature, we can definitely see across the world how different soil, climate affects the flavour profile, so we’re pretty sure we’ll see a unique profile for the different parts of Australia,” Dr Williams said.

“We want people to describe the coffee based on their sensory descriptors, so we want to know whether our coffee grown here is more fruity than coffee grown overseas, and we want to know whether we have more flowery coffee or we want to find the characters that stand out for local coffee,” Dr Ben Liu said.

“We already found a significant difference between the coffee we grow here, and the coffee grown in other parts of the world through our instrument, but the next thing is trying to link the chemical signatures to the tasting panel research.”

Six people in a room under red light tasting coffee.

Dr Simon Williams (second from right) leads a tasting panel in Brisbane.The red light prevents the coffee from being judged by its colour.(Supplied: Ben Liu)

But that key step of the research has been delayed due to COVID-19 restrictions limited travel to Sydney and Queensland to host panels with coffee growers, roasters, green bean importers and baristas.

Dr Liu said the project’s target was to increase demand for Australian coffee, here and overseas, to improve or maintain its quality, and to encourage more farmers to grow the crop.

Posted , updated 

Coffee growers look to boost productivity with small trees
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