Ancient wheat fights back for farming

CBAM was one of the other bits of bad news sneaked out in the UK Budget a few weeks ago. Ostensibly it is being brought into operation to stop the importation of high-energy goods which have been produced in countries without our own strict environmental and greenhouse gas emission controls and levels – which might allow them to undercut home-produced goods by using ‘dirty’ production methods.

But with no domestic nitrogen fertiliser production facilities remaining in operation in the UK, extending this new tax to one of our key crop-growing inputs in the Budget was undoubtedly both misguided and futile, as well as being punitive to growers.

Additional slap in the face

However, with the focus of the demonstrations and rallies held earlier this week being focused firmly on the changes to inheritance tax relief, this additional slap in the face might be something which we’ll all have to face up to when it comes into operation in January 2027.

So, if we’re forced to concentrate our efforts on other battles and simply turn the other cheek on this one, it will only go to reinforce the moves which have been taking in recent years and which have led to a bit of change in the way we assess new cereal varieties.

Newcomers’ responses under reduced spray and fertiliser regimes are now being much more closely scrutinised – both commercially and by the AHDB when they draw up their recommended lists – with an eye which is no longer attracted exclusively to out-and-out yield.

However, a piece of research which came out recently might also add to the mix and help focus efforts towards breeding new varieties which allow optimal yields to be produced at lower rates of fertiliser use.

Work just published by Rothamsted Research has shown that modern wheat varieties grown with bagged fertiliser have far fewer beneficial root bacteria of the type which can help plant growth compared to their unfertilised counterparts.

Maybe not an overly surprising finding as there’s often a pay-off as we push any natural system. But in contrast, it would appear that ancestral wheat varieties show no such reduction whether fertilised or not, and can still call on their microbe friends to help them out.

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Overly-pampered softies

Researchers have suggested that this is because modern cultivars have been bred to rely on nutritional inputs to maintain yields, effectively becoming overly-pampered softies.

The study highlights that there is a strong potential to use some of the older, less ‘entitled’ ancient varieties to harness the advantages offered by beneficial microbes and allow plant genetics to make a move to lower-input farming systems without totally jeopardising yields.

Part of the reasoning seems to indicate that modern wheat varieties have complex genomes with either four (tetraploid) or six (hexaploid) sets of chromosomes – a result of extensive crossing and interbreeding which both farmers and plant breeders have carried out over the years and decades. Ancestral varieties, however, have simpler genomes with only two (diploid) sets of chromosomes.

The research team performed controlled experiments to compare growth-promoting root bacteria (known as plant growth-promoting rhizobacteria or PGPR) associated with diploid, tetraploid, and hexaploid wheats grown in both fertilised and unfertilised soil, resulting in the isolation of over 14,000 bacterial isolates.

“Modern wheat varieties have been bred to thrive in high-input systems,” said Dr Tessa Reid, the study’s lead researcher. “This appears to have greatly reduced the numbers of beneficial bacteria living on or around their root system. If we are to move to lower-input systems, we will need to work out how to boost the abundance of beneficial soil microbes, so that they provide the nutritional benefits currently delivered by inorganic fertilisers.”

Beneficial root bacteria

The team found that fertiliser application reduced the abundance of these ‘good bugs’ in polyploid wheats by 45%, making their levels no higher than in soils devoid of root systems.

This reduction was not observed in diploid wild wheats, the ancestors of modern varieties – and the scientists believe that this has been largely driven by a reduced selection of beneficial root bacteria over the decades and centuries which has led to modern wheat varieties. And one of the best types of friendly bugs, the Bacteroidota, seems to be particularly hard hit by this selection pressure.

The research has indicated that improving the microbiota of modern crops to the levels seen in their ancestors could offer a way to enhance sustainable food production and harness the free benefits provided by these symbiotic root relationships.

Future work will involve performing a microbiome transplant whereby the microbes which were identified as being lost through domestication will be inoculated to modern wheat varieties to identify whether beneficial effects from these microbes can be re-established.

Better relationships

Alternatively, the reintroduction of key genetic elements to modern plants from their ancestors, by selective breeding or gene editing, for the selection of better relationships with beneficial microbiota from the bulk soil reservoir, could be another way of achieving results.

So, if they offered real and measurable gains from an improved relationship between crop roots and rhizosphere-beneficial microbe in modern wheat, we might be looking at one way of making them less reliant on such hefty doses of increasingly expensive fertiliser.

While that might just be one instance of utilising better spoil health to boost yield potential while reducing input costs, the recent review of the AHDB’s national recommended list has shown that this sort of approach is becoming of increased interest to growers the length and breadth of the country.

Among the views gathered in the review it was pretty clear that a turning point has been reached: outright productivity is no longer the sole selection factor for new varieties.

As the industry faces up to increasingly erratic weather patterns and changeable pest and disease pressures, while at the same time meeting the requirements to protect the environment, more things are being sought from new varieties.

Conducive for cereal production

Despite a lot of the doom and gloom, recent research has shown that the climate – at least in the UK – is likely to remain conducive for cereal production until at least 2080. Warmer temperatures may even positively impact average wheat yields in the major UK growing regions.

However, this good news is tempered by the predicted increases in year-on-year variation, with adaptation needed to soften the blow. And as recent seasons have exemplified, growing conditions can flip from one extreme to another between seasons.

This all adds up to increasing uncertainty, which is a massive challenge for farmers and breeders.

But breeding more resilient varieties which can provide a more reliable and consistent levels of yield and quality – even if not always the highest (and especially if this can be achieved with the benefit of a lower degree of reliance on expensive inputs) – in these different weather patterns has to be a key aim for breeders and growers in the future.