Rachel Williamson
IT’S THE LATE 1930s and wheat croppers in Victoria are very worried.
Total wheat yield in the state has fallen for 50 years, despite the introduction of the famous designer Australia strain Federation 30 years earlier.
Farmers have tried new fertilisers and different seed varieties, but nothing is working. They are prepared to try anything – even science.
Over at the state Department of Agriculture, researchers suspect the old technique of a fallow, or idle, year between crops is part of the problem. The practice simply isn’t delivering enough nitrogen back into southern Australia’s ancient soils for intensive wheat farming.
Enter Yvonne Aitken. She’s one of the few women working in agricultural sciences — and only because a high school teacher’s brother endorsed the sector as “all right for women”.
In 1938, 27-year-old Aitken’s work into why some plants flower earlier or later might hold the key to fixing Victoria’s wheat slump. The theory is this: what if farmers add an earlier flowering crop into their rotation, which also has intensive nitrogen-fixing abilities, like peas?
“The peas could supply a high protein seed crop and also raise soil fertility through the manurial value of the pea stubble from sheep grazing and from the nitrogen-fixing activity of the Rhizobium nodules on the pea roots,” wrote Nessy Allen in her 1997 biography of Aitken for The Agricultural History Review journal.
“It was the practical problem of developing plants which could do that to which [Aitken] applied herself for so long and which she so successfully solved.”
The nine-year project would see the woman from Horsham gain the moniker “Miss Peabody”, which she told Allen was due to her then-unusual habit of wearing a hat when out in the fields, and for adding another tool to the library on how to grow wheat in Australia.
Aussie wheat, and the science of how it became one of the biggest agricultural products in the world, is a story of fighting disease, of deep knowledge of subterranean worlds, and of the God-like process of designing a bespoke seed for Australia’s unique conditions, yet adaptable enough to sell anywhere.
Throughout the 235-year history of wheat growing in Australia, there have been farmers on one side – experimenting, testing, figuring out the land’s quirks – and scientists on the other, doing the same thing.
From First Fleet to Green Revolution
The first Australian wheat grower was farmer and convict James Ruse in 1789. Australia was his sliding doors moment. He was supposed to be transported to Africa for seven years for burglary but instead did his time on a prison ship in Cornwall before being packed onto the First Fleet in 1787. Two years later he convinced Governor Arthur Phillip to let him go and work out how to make English wheat grow in the humid climes around the Parramatta River. Ruse reaped about five tonnes that first year, as seen in historical records now held by the Australian Bureau of Statistics (ABS).
What followed was a rapid expansion of cropping across the temperate zones of Australia. Yet throughout the next century, droughts and fungal epidemics emphasised again and again the inadequacies of Northern Hemisphere wheat varieties for the land down under.
The 19th century was a period of exploration. South Australian experimenters bred for early maturity and drought tolerance as well as resistance to rust, a disease that still crushes yields by 50–100% according to the New South Wales Department of Primary Industries.
During this time William Farrer – retired surveyor, self-taught biologist, failed mining investor, and farmer – perfected his designer grain, Federation wheat. It was rust resistant, tolerant of the dry, and high yielding.
Commercialised in 1903, Federation was a cross between another of Farrer’s own creations, Yandilla, and a type called Purple Straw whose origins were traced to southern Europe in a 2017 study of Australian wheat genetics.
Federation was Australia’s first big step toward becoming a cereals powerhouse.
The second big leap forward did not come from Australia, but from Mexico’s International Maize and Wheat Improvement Center (CIMMYT) and the global Green Revolution.
In the 1960s, crop-based food production took off around the world, partly thanks to genetically modified, high yield varieties of popular crops that were bred by Nobel Prize winner Norman Borlaug at CIMMYT. For Australian wheat growers, it was his dwarf wheat spun out of a Japanese strain, which needs less fertiliser and water, that shot the industry in a new genetic direction.
Those two leaps allowed Australia wheat yields to rise by 3,000% over the 20th Century, according to ABS data.
Today, Australia is one of the global top exporters of wheat. It was dethroned last year from first place by Russia. But ABS stats show farmers turned that first five-tonne crop in 1789 into a 36 million tonne bonanza in 2022.
Indeed, in 2022–23 wheat was Australia’s biggest export of all agricultural, fisheries and forestry products at $16.7 billion in value, with beef and veal coming in a distant second at $10.7 billion, shows Department of Agriculture, Fisheries and Forestry data.
But despite what the yield figures say today, once again, not all is well in Australian wheat. A climate-based ceiling is threatening.
Since 1990, water-limited yields have fallen by about 1% a year every year as average rainfall slowly decreases over time, says former CSIRO researcher Dr Zvi Hochman. That works out to a decline from 4.4 tonnes per hectare (T/ha) in 1990 to 3.2T/ha in 2015.
Water-limited yields are the maximum potential for any piece of land, if the only thing to worry about is water.
And yet so far Australia is not feeling the effect. Genetic modifications, finely-tuned farming practices that retain moisture in the soil, the generous application of fertilisers, rotational crops to disrupt weeds and disease cycles, and plants bred for specific conditions, allow farmers to continually magnify what their land can do.
The new gods
Agriculture has always been the art of manipulating genetics, be it to harvest the best wheat, sire the prizewinning bull, or grow the finest wool. But today’s gods of creation are doing it at the level of genes.
Dr Scott Boden at the University of Adelaide is working on pumping up yield, or the grains per plant.
“We’ve discovered a whole suite of genes that are responsible for controlling for a number [of grains],” he tells Cosmos.
“We want to now study those genes in more detail. We’ve already done that with two of the genes discovered in this project. [We] found that when we modified the function of these transcription factors [altering the proteins that convert or transcribe DNA into RNA], we could accelerate flowering, and we could get the plant to change how many grains it produces.”
Boden’s team wants to investigate the other 100,000 or so genes in the wheat floret. Enter the University of Adelaide’s CoreDetector plant genome-sequencing machine which can decode “gigabyte plant genomes”, says the project co-lead Dr Julian Taylor. The software can unravel wheat genomes in two hours.
The implications of the study, published this year in Current Biology, and technology such as the CoreDetector are huge. Two decades ago the Food and Agriculture Organization of the United Nations said food production needed to rise by 50 per cent by 2050 to feed the world, and that crop yields will need to do most of the heavy lifting – they need to rise by 80%. Growers need genetics like these to beat the water ceiling, and knowing which plants have which genes allows breeders to hone their specimens more quickly.
And what if they have no good genetic mutations to work with? The next step is genetic modification.
Twelve years ago, the DNA sequence CRISPR was used to scissor genetic code for the first time. Agricultural scientists haven’t looked back. Boden says they can now introduce mutations which target genes in a specific way.
“Rather than guessing where these genetic modifications are going to happen within the plant, we can target them and we can then track them very easily afterwards,” he says.
“That’s what’s been a big game changer for genetic modifications relative to what we understand from the 1990s, where Greenpeace would protest against genetic modifications. [Back] then we knew what we were introducing into the plant, but we didn’t always know where it was going to go.”
Australia has allowed limited releases of genetically modified wheat since 2005 to improve tolerance to heat, cold, drought and salinity, to improve grain quality and yield stability as well as disease resistance, according to trial data held by the Australian federal Office of the Gene Technology Regulator.
The regulator’s records show 26 trials of genetically modified wheat have either finished, been withdrawn, or are currently underway. The current trial hubs are at the University of Adelaide’s Barossa Valley trial site, the University of Melbourne’s Dookie College east of Shepparton – the location of Aitken’s pea study – and CSIRO’s plots at Hilltops in New South Wales.
But the reward of creating more and more bespoke plants comes with risk as well: Australia’s wheat genetic base is narrowing because of the tightly controlled crossing of varieties since the Green Revolution, found Dr Reem Joukhadar in her 2017 study of wheat genetics.
“This shrinkage in diversity creates a need for urgent actions to cope with future environmental changes,” Joukhader and her coauthors wrote.
“New allelic diversity can be introduced to current Australian germplasm from pre-Green Revolution cultivars or from the geographical regions that dominated the Australian germplasm during the second period… Many of these geographical regions have similar climates to Australia and could potentially improve Australian wheat and avoid further loss of genetic diversity.”
From lab to field
Surely the Holy Grail of genetic modification and breeding is to deliver designer, almost made-to-order wheat? Queensland farmer Ben Taylor says this is almost – almost – what he’s already getting.
Taylor co-owns a 5,000 hectare farm on the Western Downs with his wife Kate and brother Sam. They’re semi-famous in agri circles for turning the business around by fixing soil health and using a tailored crop rotation system.
They give back to the industry by hosting Australian Grain Technologies (AGT) and Grains Research and Development Corporation (GRDC) wheat trials.
“The current breeding program is doing exactly that [creating designer seed] to improve varietal traits depending on whether it’s yield, disease, drought tolerant varieties,” he told Cosmos, after dashing in the door from a chat with the manager of the 6,000 AGT trial plots on his property.
“We’ve got a new AGT variety called Intrigue and it’s showed year-on-year in the NVT trials [National Variety Trials] some really great yield results, maybe 5% more than our current variety. If you have an incremental increase of 5% every five years, it adds up.”
The Taylors will store and use three to five grain varieties for anywhere between three and five years, before turning them over for new strains that have better protection against the likes of rust, the fungal disease that has plagued Australian growers since the first crops, and the Western Downs-specific nemesis, crown rot, a fungal root disease that sets in during dry weather.
The continual stream of new varieties, combined with farming practices finely tuned to Western Downs soil types, has lifted yields at Culara Farm from a top figure of 2.45T/ha in Ben’s and Sam’s grandfather’s day, to 5–6T/ha today.
While Taylor would “absolutely” buy a made-to-order seed that fixes for the bespoke wheat diseases in his area and improves yield, it’s not as simple as tweaking some genes and Ubering over the perfect plant.
That’s because, to quote the immortal film about genetic modification, Jurassic Park, “nature finds a way”.
Rust for example, has been the bane of croppers’ existence since 1803, according to a history of the fungus published last year, because rust genes change to beat the wheat mutations which resist it.
“I have previously really resistant lines but when the pathotype changes, the rust mutates. All of a sudden it’s susceptible,” says AGT breeder Dr Meiqin Lu.
It takes anywhere from eight years to breed new traits into wheat seed that can be released commercially, which means Lu has unreleased rust-resistant varieties which the fungus has already beaten.
Artificial intelligence could solve this. The University of Queensland and GRDC are running a trial now using AI to find rust-beating genetics and simulate the result, then “speed breed” wheat faster than the fungus can mutate.
The battle of the blight
If rust has been a blight on the wheat landscape forever, a host of other bacteria, viruses and pests are ever ready to blacken a farmer’s day. The GRDC’s 2009 watchlist put the average annual cost of the 41 most common diseases and pests at $913 million.
Climate change is expected to make some of these more common. The humidity and moisture loving fusarium head blight (FHB) is one that scientists anticipate will love the southwards shift in wet and humid subtropic zones. In wet 2022, FHB laid waste to crops across eastern Australia, an epidemic GRDC called “unprecedented”, and can be dangerous if eaten by animals and humans.
There are still few wheat strains around the world resistant to FHB. The best that can be done right now is to find genetics that reduce susceptibility. Genetic editing might again be a solution. A joint Adelaide–Nanjing university investigation published this year uncovered a mutation in the TaHRC gene that makes plants resistant to FHB.
Crown rot is the more pertinent challenge for Narrabri-based Lu. Like FHB there are no good genetic strains yet anywhere around the world that actively resist this disease. This means the best they can do is design a plant that doesn’t get as badly hit by an outbreak.
“Industry has been working on this disease for a long time, but the progress is not as good as good as we would like,” Lu says.
“We made some progress and some varieties, such as Intrigue, is moderately susceptible. That’s all we get.”
Golden soil
There’s a reason why farmers like Taylor refer to their soil with words like “magic” and “gold”, because they need the bank beneath our feet to fund the continual push to get more from the same area of land.
That pressure to grow, baby, grow is beginning to recreate the troubles in Victoria in the 1930s: soil problems.
It’s been millions of years since Australia’s ancient soils were revitalised by volcanic eruptions, and never by glacial erosion. The country has the third highest rate of soil carbon loss in the world over the last 250 years, largely from land clearing, behind only China and the United States, showed a study in PNAS in 2017.
At this end of a 45-year long career, Professor Michael Bell has seen a lot of paddocks. He says a drawn-down macro and micro nutrient bank is another ceiling getting ever so slowly lower.
“The assumption was that what we yield in Australia is dominated by water availability,” he says.
“It still is to some extent, but we’ve seen increasingly that nutrient constraints are, in some cases, clearly the dominant response. The soils don’t have the give in them or the resilience that they used to have.
“The next stage of soil management is trying to feed the soil, not the crop.”
Bell and Taylor both say the problem is not fertiliser use – if the world wants more food from the same or less land, fertiliser is necessary – but how to dose it accurately.
“I can go back to my grandmother’s records in 1925 and convert the price of maize grain from pounds to dollars. And we’re not getting much more per tonne of grain now than we were back then. But they had no fertiliser inputs back in those days, [they] didn’t need it,” Bell says.
“Work we’ve done on deep phosphorous placement in Northern Australia says that if we take the opportunity to fix phosphorus deeper in the [soil], we can mine that investment over the next four or five years.”
The same experiment is being run in southwest Western Australia where soil scientists are trialling which measure of nitrogen, potassium and phosphorus those soils need and how best to apply the medicine.
And during the pandemic, six researchers occupied themselves with analysing and writing up data from a GRDC-sponsored trial on whether a native fungi, the Austroboletus occidentalis or ridge-stemmed bolete, might be used as a fertiliser alternative.
The University of Western Australia researchers grew wheat in nitrogen-poor soil which they then dosed with nothing, nitrogen-fixing bacteria, the fungi, or both stimulants. The first specimen grew 25% more
than the control, the second by 101%, and third by 106% – a no-brainer replacement for increasingly expensive synthetic fertiliser, the authors implied.
Nineteenth century farmers would recognise the battles still being fought today and the way farmers and scientists are waging them, but they wouldn’t recognise the predictive modelling or the gene editing techniques which can – almost – create designer plants.
“There is an absolute limit to what you can grow where,” says Hochman, who uncovered the frightening data showing the water-limited yield ceiling is falling.
“It’s really about new technology and new genetics that enable farmers to keep up. For how long, that is a really good question.”
Since 1788 wheat farming in Australia has been squeezed by disease and drought, sensitive soils and ill-suited plants, and now climate change. To date, scientific advances have beaten them all. But for how much longer is anyone’s guess.