Maximizing Corn Yields: Bt vs Non-Bt Hybrids in Statewide Large-Plot Trials

Sep 09, 2024

By Dominic Reisig

Bt corn growers are required to plant 20% of their total corn acres to non-Bt corn for resistance management. An important question is do growers lose yield on the 20% of the acres they plant to non-Bt corn? In addition, recent economic analysis from Georgia indicated that growers pay an average of $14 to 28 more for Bt hybrids than non-Bt hybrids. If growers lose yield planting non-Bt corn will the seed savings offset potential losses?

Previous work in the state has focused on small-plots comparing non-Bt hybrids and Bt hybrids at the Tidewater Research station in Plymouth, at research stations in North Carolina, South Carolina and Georgia (results published soon!), and in the OVTs. Across these trials we found that timely planted Bt and non-Bt hybrids from similar genetic backgrounds yield the same. In contrast there is a slight yield penalty to planting a non-Bt corn hybrid when it is planted beyond the last recommended planting date.

Therefore, according to data from 3 sets of multi-year experiments, growers who select a high-yielding non-Bt hybrid and plant it on time, will not lose yield compared to if they planted a Bt hybrid. But what if we put this into the hands of growers? How would non-Bt hybrids stack up?

Graduate student Alexis Alsdorf, recently collaborated with NCCE county agents across the state to test the efficacy and yield of non-Bt hybrids and Bt hybrids in large plot trials. We chose a non-Bt and Bt hybrid pair from both Dekalb and Pioneer. These were planted, maintained, and harvested on grower farms using grower equipment during 2022 and 2023 in 55 total fields spread across North Carolina from the mountains to the sea.

Bt hybrid efficacy was as expected. Feeding was mainly by corn earworm and was equal between both years. The hybrid expressing Cry and Vip Bt traits (DKC65-99) had very little feeding by corn earworm, the hybrid expressing Cry Bt traits (P1197YHR) and its’ non-Bt pair (P1197LR) had moderate feeding, while the non-Bt hybrid DKC67-70 had the most feeding. Note that corn earworm is resistant to the Cry Bt traits.

CROP

However, yields did not follow feeding patterns. Results were different between years, with yields tending to be higher in 2023. Importantly, yields were equal between non-Bt and Bt hybrid pairs in each year. DKC65-99 and DKC67-70 yielded the same in both 2023 and 2022. Similarly, P1197YHR and P1197LR yielded the same in both 2023 and 2022.

crop

This matched the results from the 3 sets of multi-year experiments in small plots. Growers who select a high-yielding non-Bt hybrid and plant it on time, will not lose yield compared to if they planted a Bt hybrid. In fact, they could save on seed costs on the 20% of acres they planted to non-Bt.

We encourage growers to work with their corn seed provider to select appropriate high-yielding non-Bt hybrids for their 20% refuge acres.

Source : ncsu.edu

Video: Can Gene Editing Give Seeds a Stronger Start?

Reagan Reed has a way of describing his research that might make a plant breeder pause.

“I’m the sort of person who likes to break things to understand them,” he says.

What he breaks are genes involved in seed germination. Reed, a Ph.D. candidate at the University of California, Davis, is investigating whether changing those genes can help seeds establish healthy plants under a wider range of conditions.

Reed recently attended the National Association for Plant Breeding meeting in College Station, Texas, as an NAPB Borlaug Scholar. His work speaks to a question that matters well beyond a research lab: what does it take for a seed to get a crop off to a strong start?

A seed that germinates quickly, alongside the others planted with it, spends less time vulnerable to stresses before seedlings become established.

“If you’re able to bridge that gap between germination to stand establishment, then that’s going to give you the highest probability of having a solid yield that year,” Reed says. “There’s a bunch that can go wrong after that, but it maximises your yield from the start, at least.”

Reed works in Dr. Imtiyaz Khanday’s lab at UC Davis, where his research focuses on seed quality in tomatoes and potatoes. He brings an unusual academic background to the work: at Skidmore College, he studied both biology and Latin.

Reed believes that combination prepared him for research. Translating an ancient text means studying each word, weighing its possible meanings and using context to reach the best interpretation. There is rarely a way to know with complete certainty what an author intended. Science, he says, requires a similar willingness to work through uncertainty.

“Attention to detail and comfortability working with uncertainty,” is how he sums up what Latin taught him.

In the lab, uncertainty can produce a surprise. Reed describes changing one gene and seeing little effect. Changing a second gene also appears to do little. Put both changes in the same genetic background, though, and the result can be substantial.

“I break this gene, nothing really happens. I break this other gene, nothing really happens. I combine them into the same genetic background, and now there’s a massive effect,” he says.

Those interactions matter as researchers gain the ability to edit multiple genes at once. They also complicate any simple account of how a trait works: improving a seed may depend on understanding what several genes do together.

For Reed, the question is whether that knowledge could help seeds germinate reliably when conditions are difficult. Some of the genes he studies prevent germination under certain conditions. That response may serve a plant well in one setting while limiting its usefulness in agriculture. He wants to learn what happens when those genes are changed, and whether the result improves establishment.

Yet a discovery that works in a lab still has a long way to travel before it reaches a field. Reed argues that agricultural biotechnology faces an economic challenge as well as a scientific one. New tools can create value for farmers, he says, but developing them requires a way to support the work in an industry where margins can be thin.

His fellowship with Flagship Pioneering gave him a view across AI, agriculture-related work and human health research. It also reinforced the importance of bringing people with different expertise into the same conversation—a benefit of gatherings such as the NAPB meeting.

“You need to have a team of people with different backgrounds who are willing to work together and approach the same problem in different perspectives and different ways,” he says.

That thinking connects the different parts of Reed’s path. Latin taught him to examine details without expecting a perfect answer. Gene editing lets him test what individual genes do—and what happens when their effects combine. Working with people beyond his own field helps him ask what those findings could become.

He came to agriculture because of its reach: the possibility that work by a small group of researchers could eventually make a difference on a much larger scale. His immediate focus is smaller and more precise. He wants to understand what helps a seed get through its first days and become a healthy plant.