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Planting sweet corn at high densities improves yield

A new study led by the University of Illinois at Urbana-Champaign has found that sweet corn, when planted at high densities, has steadily increased in yield over the past 80 years. This historical analysis highlights the importance of planting modern density-tolerant species of corn at their optimal densities, and suggests opportunities to further improve their density tolerance.

“Over time, steady improvement in plant density tolerance has contributed greatly to genetic yield gain in field corn. While our recent research indicates plant density tolerance in modern sweet corn hybrids could be exploited to improve yield, historical changes in plant density tolerance in sweet corn were unknown,” explained study lead author Daljeet Dhaliwal, a doctoral student in the Department of Crop Sciences at the University Illinois.

Together with Marty Williams, an adjunct professor of ecology, Dhaliwal tested sweet corn crowding tolerance in hybrids dating from 1934 to 2014. They found that, when grown at high densities, the marketable ear mass increased by a total of 2.85 tons per acre during this period, and an average of 0.36 tons per decade.

The researchers grew one or more hybrids representing each decade at both low (4,000 plants per acre) and high densities (32,000 plants per acre) over the course of three years. Next, they measured key harvest metrics, such as marketable ear mass, crate yield, and recovery. They discovered that the marketable ear mass and the crate yield improved in hybrids grown under high densities. Thus, modern hybrids appear particularly suited for growth at high densities.

“Plant architecture has become more compact. Plants are putting fewer resources into vegetative tissue, so there’s less fresh biomass and fewer tillers. That means modern plants are really suitable for growing at higher densities. There’s less interference, right? But when you plant them at low densities where there is no competition, these plants are not out-yielding older hybrids,” explained Dhaliwal.

On the other hand, the scientists found that fresh kernel mass and recovery didn’t change much over time. 

“No improvement over 80 years suggests a potential breeding objective. What if we could improve recovery?” said Williams. “Until the last decade, few sweet corn breeding programs were measuring recovery. Instead, breeders focused on other important traits, particularly eating quality and disease resistance. But now that we know how little recovery has improved, perhaps it’s worth targeting.”

The study is published in the journal Frontiers in Plant Science.

By Andrei Ionescu, Staff Writer

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