How Plants Use Light and Heat Affects Crop Growth Efficiency

Jenn Hoskins
15th January, 2024

How Plants Use Light and Heat Affects Crop Growth Efficiency

Image Source: Natural Science News, 2024

When we talk about the growth of crops, we can't help but marvel at how they harness energy from the sun—a process known as photosynthesis—to produce the biomass we ultimately rely on for food. However, not all plants do this with the same efficiency. Picture the sun as a generous stream of energy; some crops are like seasoned anglers, catching more with less, while others aren't as adept. Scientists have a term for this ability: Radiation Use Efficiency, or RUE for short. Essentially, it's a measure of how much aboveground biomass a crop can produce for a certain amount of sunlight it captures. One of the puzzles that plant scientists have been trying to solve is why certain advanced hybrids of maize and grain sorghum differ in their RUE. Indeed, both plants are important staples, feeding millions, yet they don't perform equally under the sun's spotlight. In a recent study conducted by a diligent team at the Queensland Alliance for Agriculture and Food Innovation, they took up the challenge of cracking this conundrum—using an inventive "top-down" approach by focusing on the canopy of the crops, the plant's collective 'solar panel', so to speak. They developed a model that mimics canopy photosynthesis—the grand total of all the leaves working together to convert light into food. Instead of fishing for answers by looking at one leaf at a time, they developed a new method to measure the photosynthetic response that could handle the big picture—taking into account the whole canopy. They combined this with a Bayesian model, a sophisticated type of statistical analysis, to come up with well-rounded sets of photosynthetic parameters that account for how these plants react not just to carbon dioxide and light, but also to temperature. From my personal viewpoint, I find it commendable that researchers are pushing the boundaries of traditional approaches to plant physiology. It's a bit like watching detective work unfold in the realm of leaves and sunlight, and it's enthralling to see the pieces come together to form a clearer image of life's engine—photosynthesis. What they discovered was quite revealing. They noted significant differences between the photosynthetic parameters of the top-performing maize and grain sorghum hybrids when looking across different leaf temperatures. Notably, these differences were observed in terms of the quantum yield of photosynthesis—which one might think of as the efficiency of the plant in converting light particles (photons) to chemical energy—and in the maximum activity of two key enzymes, Rubisco and PEPc. The researchers then took these findings and ran simulations of daily canopy photosynthesis. From this, it emerged that how the leaves respond to low levels of light and how this response changes with temperature are crucial aspects driving the RUE at the crop level. This is a big deal because it means we now have a better idea of what makes certain crops better solar energy harvesters than others. To put it another way, imagine if we were trying to improve solar panels' efficiency—we'd want to know exactly what influences their ability to convert sunlight into electricity. Similarly, understanding these photosynthetic parameters can provide concrete directions for further research, which could eventually lead to bioengineering crops to maximize their growth efficiency. Now, these findings are not merely for academic consumption. They have practical consequences. For agricultural scientists and breeders, this information forms testable hypotheses. They can now investigate these traits further and potentially breed new crop varieties with enhanced RUE. Considering the immense challenge of feeding a growing global population, particularly with the climatic changes breathing down our necks, such improvements could be a game-changer. From my perspective, seeing science inch toward tangible solutions that address real-world problems is both encouraging and exciting. It holds a promise not just of improved crop yields but also of more sustainable agricultural practices. To think that this begins with looking at the leaves on a plant in a new light is truly a testament to the ingenuity of science in solving the puzzles of nature. Though the trail is hot, there's still a length to travel before these discoveries make it from the lab to our fields. Each step forward is a step closer to a future where crops could potentially turn every joule of sunlight into a bountiful harvest. And in this case, the journey—from leaf, to lab, to loaf—is as important as the destination.



Main Study

1) Contrasting leaf-scale photosynthetic low-light response and its temperature dependency are key to differences in crop-scale radiation use efficiency.

Published 12th January, 2024

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