Do plants make sounds even when they are stressed and no one is listening? It’s not often asked, but researchers believe that the answer to this question is overwhelmingly “yes.” ” was discovered. By monitoring tomato and tobacco plants, they found that plants that were under stress from conditions such as being cut or lacking water emitted a series of popping sounds. These sounds are produced at human speech levels, which may not be the case for insects and other animals, but are emitted at frequencies too high for our ears to pick up.
Researchers at Tel Aviv University (TAU) in Israel placed tobacco and tomato trees first in a soundproof acoustic chamber with a series of specialized microphones and then in a greenhouse with low sound insulation. We then recorded the sounds the plants made when they were cut and deprived of water. They found that the plants produced popping sounds when subjected to these tests, but because the sounds were at ultrasonic frequencies, microphones were able to pick them up, whereas the human ear However, the noise could be heard by other species and provide valuable information, according to the researchers.
“Other organisms may have evolved to hear and respond to these sounds,” says senior author Lilach Hadany, an evolutionary biologist and theorist at TAU. “For example, a moth trying to lay eggs on a plant or an animal trying to eat a plant can use sound to make decisions.”
The stressed plants produced approximately 30–50 clicks or pops per hour, while the unstressed plants were relatively quiet. The sounds made by the unwatered plants peaked after about 5 days of dehydration and then disappeared when the plants began to die. The sound could be heard up to 16 feet away.
How or why plants make these sounds is unknown, but one theory for their production is the bursting of air bubbles inside the plant through a process known as cavitation. If so, the findings do not indicate active communication of any kind, but instead indicate a mechanical response to stress. It means that it can be an integral part of how it functions.
listening and learning
While it was interesting enough to discover that plants make acoustic noises when stressed, researchers wondered whether sounds differed between plant species or when exposed to different stressors. To find out, they used a machine learning algorithm. After training, they were able to distinguish between the sounds produced by the two types of plants and whether the sounds they produced were due to logging or dehydration.
This finding means that systems can be developed to monitor plants in agricultural environments to “listen” for cues of dehydration and other stressors. In fact, the researchers focused primarily on tobacco and tomato plants, but after spending some time asking common crops such as corn, wheat and grapes, they found that these plants are also stressed. The same was true for cacti.
The next step for researchers is to put their findings into a broader context.
“Now that we know plants make sounds, the next question is, ‘Who’s listening?'” Hadany said. “We are currently investigating the responses of other organisms, both animals and plants, to these sounds, as well as their ability to identify and interpret sounds in completely natural environments.”
In the following video, you can learn more about the research and listen to the different sounds made by some stressed plants (after adjusting for the human ear).
Global Breakthrough: Plants Make Sound!
The research was published in a journal, cell.
Source: Tel Aviv University
