Stressed Plants Make Sounds
Screaming, crying, stamping our feet: we know that people make a noise when they are stressed, but did you know that plants also "cry out” sometimes? Scientists have been able to record the sounds that plants produce in response to lack of water or damage.
If you cut a stem off a tomato plant, it emits sounds that are like ultrasonic pops – like popping a bubble in a piece of bubble wrap. This was discovered by scientists from Tel Aviv University after they recorded the sounds made by tomato and tobacco plants.
Popping with stress
Nature is not as quiet as we thought. Even healthy plants occasionally make quiet "pops", but when they are not watered or have their stems cut, they really make themselves heard. Not every stress situation results in the same sounds: with the help of AI, the researchers were able to distinguish between the sounds made by thirsty plants and those that were damaged.
Tomato and tobacco plants were the focus of the study because they are relatively easy to grow in a laboratory, but the team included other plants too. They found that cacti, grape vines, maize and wheat also make sounds when they are stressed.
No communication
The sounds made by plants are so high-pitched that they are inaudible to humans, but many insects and mammals can pick them up. So now, there is some interest in examining how these animals react to the sounds of plant stress. For example, they might react by not eating the stressed plants or by not laying eggs on them.
According to the researchers, these sounds do not necessarily mean that the plants are "communicating”. After all, there is no evidence that they make the sounds intentionally. The popping noises could be caused by a phenomenon called cavitation. This is the formation of small air bubbles in the plant's vessels transporting water. The expansion and collapse of air bubbles may cause a small plopping sound.