Scientists warn flowering-stage heat stress could devastate wheat production

Heatwaves hitting wheat crops during flowering could slash global harvests far more severely than drought in future, scientists have warned.

New research suggests that short periods of extreme heat and drought at this critical stage of development could become one of the biggest threats to wheat production in the decades ahead.

Flowering is the stage when wheat plants set grain, making it crucial in determining final yield and overall harvest size.

The study from Rothamsted Research used advanced climate projections alongside the Sirius wheat model to assess how future weather extremes may affect wheat yields worldwide.

As climate change drives more frequent and intense heatwaves, farmers are facing growing uncertainty over crop performance during key growth periods.

Dr Mikhail Semenov, Mathematical Modeller and Emeritus Fellow at Rothamsted Research, said flowering is a particularly vulnerable phase.

“Flowering is one of the most sensitive stages in wheat development. It’s when the plant sets grain, which ultimately determines yield,” he said.

“Even a few days of very high temperatures or severe water stress at this stage can reduce grain numbers and significantly cut final harvests.”

The findings point to a major shift in the balance of risk.

At present, drought during flowering causes greater yield losses than heat. Researchers stressed drought remains a major threat, but heat extremes are rising faster and are expected to have a greater long-term impact.

By contrast, heat stress during this grain-setting period is projected to become significantly more damaging. By 2050, global yield losses linked to extreme heat at flowering could rise by around one-third.

By 2090, those losses could increase by more than three-quarters, highlighting the scale of the challenge facing wheat growers worldwide.

The researchers predict heat-related yield losses will accelerate sharply after mid-century as temperature extremes become more common.

While the study focuses on global production, UK growers could also face greater risk as summer heat extremes increase across northern Europe.

Professor Malcolm Hawkesford, Leader of the “Delivering Sustainable Wheat” Institute Strategic Programme at Rothamsted Research, said the results underline the importance of breeding crops for future conditions.

“This kind of modelling studies provide critical information on, and pointers to, the traits we should be breeding for now, ready for predicted future climate conditions,” he said.

For farmers, the research highlights the need to choose varieties with improved tolerance to both heat and drought, and to consider sowing dates and management strategies that reduce the likelihood of flowering coinciding with peak temperatures.

Growers may also need to focus more on soil moisture conservation and irrigation planning where possible, alongside staying informed through seasonal forecasts and local climate trends.

With global demand for wheat continuing to rise, protecting yields under changing weather patterns is essential for long-term food security.

The research suggests the future of wheat production may depend on adapting to heat stress at the crop’s most vulnerable moment.