Researchers Show the cause of Productivity Loss in the Fluctuating Light of Maize Crop Canopies

Oct 12, 2022

A team from the University of Illinois has measured the dynamic leakiness of CO₂ from C4 plants. Previous studies had measured the leakiness under steady-state conditions, but this group took the measurements to prove that leakiness can and should be measured as a dynamic parameter.

"Last year, we predicted that during photosynthetic induction, C4 cycle activation is faster than the Calvin-Benson cycle, which would cause more CO₂ leaking, but we didn't have any evidence," said Yu Wang, a postdoctoral researcher at Illinois, who led this work for a research project called Realizing Increased Photosynthetic Efficiency (RIPE). "Now our results prove it's real. We have the first measurements of the leakiness under dynamic conditions."

While the group's previous prediction, published in the Plant Journal last year, was a proven concept, these first-of-their-kind measurements show that their modeling of the C4 and C3 photosynthetic cycles are accurate. Their recent work, studying sorghum and maize, was published in New Phytologist.

"Our research shows that during photosynthetic induction, the activation of C4 cycle is faster than the Calvin-Benson cycle," said Wang. "This is why leakiness is higher for the first several minutes after the light comes on."

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Video: From Students to Solutions | On The Brink: Season 2, Episode 14

Ask Canada’s most decorated soybean breeder his favourite part of the job and he doesn’t name a single variety. He names the students.

Istvan Rajcan is a professor of soybean breeding and genetics in the Department of Plant Agriculture at the University of Guelph, where he has run the soybean breeding program for 28 and a half years. In that time he has developed 87 soybean cultivars, published 140 refereed papers and trained 51 graduate students. In 2025 he received the Public Sector Impact Award from the National Association for Plant Breeding.

He is also worried. In this episode he says Canada is at a crossroads, pointing to recent government cuts to plant breeding programs and to the facilities that support them. His prescription is structural. "Plant breeding funding formula has to be a long-term one," he says.

The formula he is defending is the public-private matching arrangement his program runs on. Private seed companies fund the work, provincial or federal money matches it, and the combined pool stretches each dollar further than either source could alone. At the National Association for Plant Breeding annual meeting in June, he says American public breeders were often surprised at how well that collaboration works in Canada.

He also describes how the people entering plant breeding have changed. His early graduate students came mostly from farms. More recently they include, in his words, "city kids who just became excited about genetics."

Topics covered:

Why public-private plant breeding funding in Canada needs a long-term

commitment rather than a larger one

How matching private seed company investment with provincial and federal

dollars multiplies research capacity

How the graduate student pipeline into plant breeding has shifted from

farm kids to city kids