Researchers Studying Leaf Angle Aim To Improve Yields, Inspire Young Scientists

Aug 18, 2022

The angle of the leaves on a corn stalk directly affects the plant's ability to soak up the summer sun needed for photosynthesis.

Breeders have developed various corn hybrids with an upright leaf angle, as opposed to a flat leaf, to assist in the photosynthetic process and improve crop yields, particularly in densely planted fields. Still, the genetic mechanisms that control this trait are relatively unknown.

To better understand the underlying structure of leaf angle, an interdisciplinary research team, led by Iowa State University's Jianming Yu, is working to identify the genes using a robot developed at Iowa State to capture 3D images of corn in the field as well as transcriptomic- and CRISPR-based tools. The research has the potential to aid in the engineering of new hybrids and boost yields.

"Knowing the exact genes and genetic mechanisms will make the future of breeding more efficient," said Yu, a professor of agronomy and Pioneer Distinguished Chair in Maize Breeding. "Corn is a model crop and the information we gain can be leveraged by other crops, such as sorghum and millet, to improve their process."

Deploying a robot in the field

Previous large-scale field studies have examined one or two selected corn leaves to study leaf angle. But since leaf angle can vary across the canopy of a corn field and along the stalk of a single plant, affecting the amount of light reaching each leaf, Yu and his colleagues are taking a different approach.

The research team will deploy a robot, called PhenoBot 3.0, to navigate the narrow rows of corn and capture 3D images of thousands of corn plants from different viewing angles and at multiple heights to automatically detect and measure leaf angles from the bottom to top of each plant. PhenoBot 3.0 (watch above video to see it in action) was developed by Lie Tang, a member of the research team and a professor of agricultural and biosystems engineering at Iowa State.

"Using an AI-driven image processing algorithm to automate leaf angle measurement, we can use the PhenoBot to efficiently collect and analyze the data from the field," Tang said. "Based on the results from preliminary studies, which we compared to measurements collected manually, the algorithm is very accurate."

Yu added, "With this enabling technology, we can better connect with DNA data to pinpoint genes and understand biology. That is where additional research in developmental genetics and CRISPR gene editing part of the research comes in."

Inspiring future scientists

Yu says the interdisciplinary research team is a good example of how biologists, engineers and plant scientists can take a holistic approach to a problem and find a solution. To inspire interest in future scientists, the team will work with K-12 educators to plant school gardens and help students learn about plant biology, agriculture and crop improvement.

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Video: Spring 2026 weather outlook for Wisconsin; What an early-arriving El Niño could mean

Northeast Wisconsin is a small corner of the world, but our weather is still affected by what happens across the globe.

That includes in the equatorial Pacific, where changes between El Niño and La Niña play a role in the weather here -- and boy, have there been some abrupt changes as of late.

El Niño and La Niña are the two phases of what is collectively known as the El Niño Southern Oscillation, or ENSO for short. These are the swings back and forth from unusually warm to unusually cold sea surface temperatures in the Pacific Ocean along the equator.

Since this past September, we have been in a weak La Niña, which means water temperatures near the Eastern Pacific equator have been cooler than usual. That's where we're at right now.

Even last fall, the long-term outlook suggested a return to neutral conditions by spring and potentially El Niño conditions by summer.

But there are some signs this may be happening faster than usual, which could accelerate the onset of El Niño.

Over the last few weeks, unusually strong bursts of westerly winds farther west in the Pacific -- where sea surface temperatures are warmer than average -- have been observed. There is a chance that this could accelerate the warming of those eastern Pacific waters and potentially push us into El Niño sooner than usual.

If we do enter El Nino by spring -- which we'll define as the period of March, April and May -- there are some long-term correlations with our weather here in Northeast Wisconsin.

Looking at a map of anomalously warm weather, most of the upper Great Lakes doesn't show a strong correlation, but in general, the northern tiers of the United States do tend to lean to that direction.

The stronger correlation is with precipitation. El Niño conditions in spring have historically come with a higher risk of very dry weather over that time frame, so this will definitely be a transition we'll have to watch closely as we move out of winter.