Fit for the future – When yield gives way to shield

According to the UK Centre for Ecology and Hydrology (UKCEH), an independent, not-for-profit research institute, harvest 2020 was the country’s worst for at least 25 years.

Crop maps produced annually by UKCEH and Remote Sensing Applications Consultants use satellite data to show the type of crop grown in all two million fields across Great Britain. Last year’s map revealed the area of winter wheat grown was down across the whole country by 44%, winter barley by 37% and the OSR area dropped by 38%, compared with the average for the previous five years. Autumn-sown crop coverage in the East Midlands was worst hit at around 70% down.

Separate UKCEH analysis of detailed data on yields collected during harvest from more than 500 fields across 100 farms in England has shown an average fall in yield across these crops of around 15%, compared to the five-year mean, with the yield in some places down by as much as two thirds.

It’s a direct result of the weather, says UKCEH’s Dr John Redhead, but this cannot be seen as a one-off. “Climate researchers generally agree that the way climate change will manifest itself in the UK is in wetter winters and hotter summers with less rainfall.

“The UK is unlikely to see a smooth transition to a warmer climate in the years ahead with increasing likelihood that it will be typified by periods of extreme weather with the result that we will experience more years like the last one.”

Using inputs in a more targeted way that gets the most out of them will be a key part of any sustainable production system in the future, he says.

“Such thinking not only makes economic sense. It’s also likely to benefit the environment and help to reduce the causal effects of climate change in the first place.”

John Redhead believes it’s not just a question of taking a fresh look at how crops are grown but also the composition of future farmed landscapes.

“Given an increasingly extreme and unpredictable climate, it’s important to begin to diversify our cropping systems to spread the risk. It’s also important to understand how non-cropped land might impart resilience to such extreme events.

“An emphasis on a greater diversity of approaches would be of benefit and this is certainly borne out by our results suggesting that some degree of ‘land sharing’ rather than total ‘land sparing’ is a more resilient model for the future.”

Going all out for yield might not be the best option for the future, John Redhead suggests, and the UKCEH analysis of landscapes backs this up. What the scientists found was that landscapes which delivered the highest relative yields did not necessarily maximise yield stability nor resistance to extreme events in the long-term.

“Yields were most stable in landscapes with high coverage of both arable land and semi‐natural habitats, which can include grasslands with some degree of agricultural management, evenly distributed throughout the landscape,” he says.

“This suggests that there are potential trade‐offs to be made in managing landscapes for resilience over shorter versus longer time‐scales and this will be an important challenge to address in developing sustainable agricultural systems in the future,” concludes John Redhead.

Breeding for the future

For the grower, this may feel like a dim and distant future, but it’s one KWS head of wheat pre-breeding Jacob Lage is dealing with today.

“It could take 20 years for noticeably warmer, drier summers and wetter winters to come to the UK, but it takes at least 10 years from the first cross to bring a new variety to market,” he notes.

“So we’re bringing the traits in now that will make wheat fit for the future. We’re also identifying any gaps there may be in the gene pool and looking at exotic material to see whether we can breed in characteristics that will ensure even greater resilience.”

So how is Jacob addressing the five key impacts of climate change John Miles has picked out? “When it comes to establishment, we’re now on the verge of making routine use of drones in the breeding plots,” he reveals.

“The key is to spot the differences as soon as the plant emerges. With drones you can survey thousands of plots and compile very accurate datasets. That’s giving us the metrics to understand how individual crosses will perform across a whole range of scenarios.”

While the breeding system ensures nothing with poor germination ever gets through, there are differences, notes John. “The most interesting material comes out of challenging conditions. KWS Cranium powers through from a late sowing in Dec or Jan, for example.”

Jacob notes that increasingly wheats are drilled in no-till situations. “We have to respond to that and select varieties with early vigour without the benefit of mineralised N from disturbed soils. We’re always looking to associate the genetics with what we see in the field, but with these traits that’s super complex as there’s a whole range of genes interacting to give the characteristic you’re after.”

Growers are also looking for a broad portfolio of wheats, notes John Miles, to spread the workload when suitable windows seem to be getting increasingly narrow. “It’s where varieties like KWS Parkin fit in – early to drill and early to combine, too.”

A changing climate will inevitably result in a shift in pest and disease pressures. “It’s where the advantage of having a pan-European breeding programme comes in,” notes Jacob.

“We may see more issues with fusarium in the UK, for instance, and there’s some promising resistance we’re selecting for in French and German lines that we can bring to the UK. We’re also working closely with the academic community on public-funded pre-breeding programmes such as Designing Future Wheat, identifying traits and resistant genes in exotic and landrace varieties.”

Standing power is a trait UK breeders have always selected for, however. “The UK is relatively high-yielding with top-heavy varieties that have always needed some of the stiffest straw in Europe, so UK wheats are in a good position,” says Jacob.

But again it’s not a trait with a close genetic association and relies on robust screening to ensure a new variety introduction doesn’t literally flop. John Miles adds that growers in the Fens are often the first to call out a wheat that slips through the lodging net. “You rarely get weak-strawed varieties, but KWS Siskin was one where some growers found its credentials didn’t stand up in the field. Parkin does particularly well, though, being shorter and notably stiffer than many others.

“It’s also worth noting that standing power conflicts with early season vigour – if you’ve selected for one, you’ll have to manage the other.”

Drought tolerance and the ability of a wheat to withstand high summer temperatures are again characteristics that come through from the pan-European programme. French wheats in particular tend to have a faster maturity than UK types, and suitable crosses can be selected that have a fit in drier UK situations.

“There’s a good range of maturity in UK wheats, from Parkin that’s Grafton early to Cranium that’s a +2 on the AHDB Recommended List. It’s important to have a range of all varietal qualities, taking a more holistic view. If you select simply on the basis of 0.5t/ha yield difference, that’s a benefit you’re increasingly unlikely to see as the climate becomes more challenging,” John Miles concludes.