You really can hear corn grow

U.S. researchers say isolating this sound has given them 
surprising insight into plant growth

There’s an old farmer’s tale that says, “On a quiet night you can hear the corn grow.”

It may seem funny, but Douglas Cook at New York University and colleagues Roger Elmore and Justin McMechan, at the University of Nebraska were able to use contact microphones to directly record the sounds of corn growing.

Corn is the leading grain crop in the world with more than 350 million metric tons harvested yearly in the U.S. alone. But a lack of understanding about the mechanics involved in wind-induced cornstalk failure has hindered further improvements in corn production. Crop scientists have been working on this problem for more than 100 years, albeit with only marginal success.

Now, by applying mechanical engineering tools and techniques, a group of engineers and plant scientists led by Cook is making headway addressing this problem as well as discovering other issues related to plant growth and development.

“Material breakage is a lot like a microscopic earthquake: the sudden release of internal stresses sends sound waves radiating in every direction,” Cook explained. “We’re using special sensors called piezoelectric contact microphones to monitor the sounds emitted by cornstalks just before failure. This helps us understand the failure process more clearly.”

So what does it sound like? “Surprisingly, it sounds remarkably similar to the sounds made when corn breaks,” Cook said. “We now think that plant growth involves millions of tiny breakage events, and that these breakage events trigger the plant to rush to ‘repair’ the broken regions. By continuously breaking and repairing, the plant is able to grow taller and taller.”

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