Plants emit sounds – like bubble wrap being popped – when stressed, scientists have found.

Human ears cannot detect these noises because they are emitted at high frequencies but researchers believe insects, other mammals, and other plants might be able to hear these pops.  

Professor Lilach Hadany, an evolutionary biologist and theoretician at Tel Aviv University in Israel, said: “Apparently, an idyllic field of flowers can be a rather noisy place. It’s just that we can’t hear the sounds.”

While high-frequency – ultrasonic – vibrations have been recorded in plants before, the scientists said this is the first evidence that these sounds travel through air, with the findings published in the journal Cell.

“In this study we resolved a very old scientific controversy: we proved that plants do emit sounds,” said Prof Hadany, a senior author on the study.

“Our findings suggest that the world around us is full of plant sounds and that these sounds contain information – for example about water scarcity or injury.

“We assume that in nature the sounds emitted by plants are detected by creatures nearby, such as bats, rodents, various insects, and possibly also other plants that can hear the high frequencies and derive relevant information.  

“We believe humans can also utilise this information, given the right tools, such as sensors that tell growers when plants need watering.”

The researchers recorded healthy and stressed tomato and tobacco plants using microphones that have the capability to capture ultrasonic sounds between 20-250 kilohertz (humans can detect frequencies of up to 16 kilohertz).

To create stress, the researchers did not water some of the plants for several days and cut off the stems of others.

After recording, the scientists used machine-learning algorithms to differentiate between thirsty, cut and unstressed plants. The team found stressed plants made more noise compared to unstressed plants, with some emitting around 30-50 of these pops per hour.