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| Dr Robert Caine Photo Credit: Courtesy of University of Sheffield |
Wheat crops prioritize water loss during extreme future climate conditions, according to new research from the University of Sheffield
The study, led by Dr Robert Caine and Dr Holly Croft from the School of Biosciences at the University of Sheffield, revealed wheat crops lose many of the key water-saving benefits usually associated with growth at higher atmospheric concentrations of carbon dioxide when plants were exposed to heatwave conditions.
These findings are vital for understanding how to optimize future wheat crop productivity and water usage. With heatwaves becoming increasingly routine as atmospheric CO2 concentration continues to rise, plant breeders will need to consider how crops use and conserve water when developing new wheat varieties to ensure it can grow effectively and survive extreme weather.
Wheat provides around 20 per cent of daily calories worldwide and is the most widely cultivated crop by land area. While yields have risen dramatically over the past century, largely due to nitrogen fertilizers, this has increased the crop's demand for water and made it more vulnerable to drought. Challenges that are especially acute in regions such as Africa, where both water and fertilizer are limited.
Typically, higher CO2 concentrations allow plants to reduce water loss due to microscopic pores on the leaf surface, known as stomata, opening less widely as plants can more effectively obtain CO2 from the air. However, when scientists examined wheat under high CO2 heatwave conditions, they discovered that stomata open much more widely, seemingly to increase water flow and help the plant cool through increased evapotranspiration.
The Sheffield research revealed that during heatwaves, wheat stomata also failed to respond effectively to changing light levels, irrespective of the CO2 growth 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. This lack of stomatal closure has the potential to reduce drought tolerance, as plants growing under higher CO2 levels in cooler conditions normally close stomata substantially as light levels are decreased.
The study also found that wheat plants boost their natural cooling ability during heatwaves by increasing water flow from the underside of their leaves, known as the abaxial leaf surface. This mechanism reduces canopy temperature by a further 2°C, helping plants stay cooler, but this is at the expense of increased water demand.
Dr Robert Caine, Lead author of the study from the University of Sheffield’s School of Biosciences, said: “Our findings provide a much clearer picture of how future climate conditions will affect one of the world's most important crops.
“Understanding how water availability, nitrogen use, and changing climate conditions affect wheat productivity is crucial to predict and sustain yields during future global climate challenges.
“Our next step is to discover what's happening inside the plant, to understand the molecular mechanisms that govern how stomata on different wheat leaf surfaces respond to a combination of rising CO2 concentration and heatwaves. If we can understand this, we may be able to adjust stomatal performance to optimize how plants grow under extreme future climates.”
Published in journal: New Phytologist
Title: Future heatwave conditions inhibit CO2-induced stomatal closure in wheat
Authors: Robert S. Caine, Muhammad S. Khan, Yixiang Shan, Colin P. Osborne, and Holly L. Croft
Source/Credit: University of Sheffield
Reference Number: eco111725_01
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