Hot, Dry Climates Call for Resilient, High-Performing Wheat Varieties

May 15, 2023

Public and private crop research organizations worldwide have worked behind the scenes for decades, bolstering the resilience of staple crops like maize and wheat to fight what is shaping up to be the battle of our time: feeding humanity in a biosphere increasingly hostile to crop farming.

In the case of wheat — which provides some 20% of carbohydrates and 20% of protein in human diets, not to mention 40% of total cereal exports — harvests spoiled by heat waves, droughts, and crop disease outbreaks can send food prices skyrocketing, driving world hunger, poverty, instability, human migration and political instability (or government change/spring revolution), and conflict.

Century-high temperature extremes and the early onset of summer in South Asia in 2022, for example, reduced wheat yields as much as 15% in parts of the Indo-Gangetic Plains, a breadbasket that yearly produces over 100 million tons of wheat from 30 million hectares of crop land.

Science and sources to toughen wheat

Along with modernized, more diverse cropping systems and better farm policies, more resilient varieties are crucial for sustainable wheat production, according to Reynolds, who added that breeders have been working for decades to stiffen wheat’s heat and drought tolerance, long before climate change became a buzzword.

“Breeding and selection in diverse environments and at targeted test sites characterized by heat and natural or simulated drought — something we’ve done for decades — has brought farmers wheat varieties that perform well under both optimal and stressed conditions and we’re implementing new technologies to speed progress and lower costs,” says Leo Crespo, a CIMMYT wheat breeder. 

Breeding revolutions

Wheat breeding is being revolutionized by advances in “high-throughput phenotyping.” This refers to rapid and cost-effective ways to measure wheat performance and specific traits in the field, particularly remote sensing — that is, crop images taken from vehicles, drones or even satellites. Depending on the wavelength of light used, such images can show plant physiochemical and structural properties, such as pigment content, hydration status, photosynthetic area, and vegetative biomass. Similarly, canopy temperature images from infrared photography allow detection for crop water status and plant stomatal conductance.  “Such traits tend to show better association with yield under stress than under favorable conditions”, said Francisco Pinto, a CIMMYT wheat physiologist who is developing methods to measure roots at using remote sensing. “A remotely sensed ‘root index’ could potentially revolutionize our ability to breed for root traits, which are critical under heat and drought stress but have not been directly accessible in breeding.”

Innovative statistical analysis has greatly increased the value of field trials and emphasized the power of direct selection for yield and yield stability under diverse environments.

Initial results from genomic selection programs, particularly where combined with improved phenotyping techniques, also show great promise. The potential benefits of combining a range of new technologies constitute a valuable international public good.

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