UK study reveals heat waves may push wheat’s water demands higher

(MENAFN) Wheat crops may require far more water than previously assumed during future extreme heat events, according to new research released Monday by scientists in the UK.

A team from the University of Sheffield discovered that wheat plants open their stomatal pores much wider during heat waves in an effort to cool themselves. As a result, the crop could consume significantly more water than current projections suggest once temperatures spike.

The study — led by Robert Caine and Holly Croft of the School of Biosciences — found that under heat wave conditions, wheat loses many of the water-saving advantages normally linked to growing in elevated atmospheric CO₂ levels.

Wheat, which supplies roughly 20% of the world’s daily caloric intake and covers more farmland than any other crop, has seen yields climb sharply over the last century. But that progress, driven largely by heavy nitrogen fertilizer use, has also increased the crop’s water needs and heightened its sensitivity to drought, the researchers said.

When scientists examined wheat exposed to both high CO₂ and heat wave conditions, they observed that the stomata opened far wider than usual, apparently to boost water flow and cool the plant through increased evapotranspiration.

The study also showed that during heat waves, wheat’s stomata largely lost the ability to adjust to shifting light levels, regardless of CO₂ concentration.

"This reduced responsiveness during heatwaves means that wheat cannot narrow its stomata effectively when light levels drop, a process that would normally help limit water loss," according to the research.

The authors warned that this weak stomatal closure could undermine the plant’s drought tolerance, since under cooler, high-CO₂ conditions, wheat typically closes its stomata much more tightly as light decreases.

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