If sunflowers were stressed, what would they sound like?
Some researchers in Israel have been studying plants and the sounds they make. Lilach Hadany, an evolutionary biologist and theoretician at Tel Aviv University is the senior author of the study. The researchers published their work in the journal, Cell. The study is called “Sounds Emitted by Plants Under Stress Are Airborne and Informative.”
Though the researchers focused on tomato and tobacco plants, they also studied other plants, among them corn, wheat, grape and cactus plants. All of them emit sounds when they are stressed. If they’re not suffering, they are much quieter. Though the researchers didn’t include trees in their study, it would be interesting to learn if trees also emit sounds when they’re stressed.
Researchers created stress in the plants by either cutting their stems or dehydrating them. In the March 30 issue of Treehugger, Melissa Breyer wrote about the interesting study. Her article is titled “Stressed Plants Make Sounds, We Just Can’t Hear Them.” You can learn more about Treehugger at https://www.treehugger.com/.
The sounds that stressed plants make are at a frequency too high for humans to hear. The sounds travel through the air. It’s possible they could be heard by some animals, insects and other plants. If an insect were thinking about laying eggs on a certain plant but that plant was emitting stress sounds, the insect might, theoretically, decide to lay its eggs on a healthier plant.
The researchers were able to hear those stress sounds by recording plants in a soundproofed acoustic chamber and then in a noisier greenhouse. They lowered the frequency so humans could hear it. They described the sounds as a little like someone popping bubble wrap.
The researchers trained a machine-learning algorithm to tell the difference between the sounds that happy plants, thirsty plants and cut plants make. The machine-learning algorithm got very good at deciphering the different noises.
It would be nice if gardeners could hear the vegetables in their gardens. If plants are thirsty, they start emitting stress sounds before people can see that they are dehydrated. That would help gardeners know which plants needed extra water.
But maybe if we could hear all those sounds, we might think the world was a little too noisy.