This is what the ‘cry’ of a stressed plant sounds like

by time news

“Even when everything seems to be quiet, in reality we’re surrounded by sounds we don’t hear“. This is the premise with which a curious study launched this Thursday by an Israeli team of researchers begins. The work, published in the scientific journal ‘Cell’, has achieved record the ‘cry’ of stressed plants by dehydration or by cutting a stem. As biologist Lilach Hadany, lead author of this study, explains, the noise emitted by plants is so loud that can be heard up to a meter away. Of course, if we do not hear it, it is because its frequency is too high for our ears to detect it.

The ‘scream’ of stressed plants has been captured by researchers at Tel Aviv University. In order to register its sound, the experts moved a series of tomato and tobacco plants (some of the easiest to grow in laboratories) first to an acoustically soundproof room and then to a greenhouse. At first, the sound of the plants in a healthy state was recorded. Later, the noise of plants that carried several days without being watered (and who showed signs of dehydration) and of plants that had had several stems cut off.

All these recordings were analyzed from a machine learning algorithm and, from there, they studied the differences in sounds between healthy and stressed plants. As explained by the experts who have led this analysis, the voice of the plants sounds like a sequence of pops or clicks. The more stressed you are, the more clicks you emit. “A stressed tomato plant emits between 30 and 50 clicks per hour at random intervals,” Hadany explains. “Sounds like crumpled plastic or bubble wrap bursting“, Add.

“A stressed tomato plant emits between 30 and 50 clicks per hour at random intervals”

‘scream’ of stress

The analysis reveals that the plants begin to ‘scream’ when they begin to run out of water. Even before suffering visible signs of dehydration, vegetables constantly emit noises to alert them of their condition. He ‘scream’ reaches its maximum intensity after five consecutive days in the absence of water and, from then on, it gradually decreases until the plant dries up completely and dies. This phenomenon has been studied in tomato and tobacco plants although, according to the researchers, it has also been observed in species such as corn, wheat, grapes and cactus.

But what is this vegetable ‘scream’ due to? The researchers explain that there are still many unknowns about how and why this sound is produced. For now, one of the most accepted hypotheses is that it could be the formation and explosion of air bubbles in the plant’s vascular system (a process known as ‘cavitation’).

who listens to plants

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“Now that we know that plants make sounds, the next question we ask ourselves is:who could be listening?”, asks Hadany after the publication of this article. His team is now preparing to investigate what type of organisms are capable of hearing (and reacting) to this type of stimuli. Previous studies have already pointed out that plants emit sounds and vibrations to communicate with each other. In the same way, it seems that some pollinators also respond to plant sounds to know when they are in the best position to collect nectar.

“Now that we know that plants make sounds, the next question we ask ourselves is who might be listening?”

“We know that there is a lot of ultrasound in nature. For this very reason, every time you use a microphone you discover that many things make sounds that humans cannot hear“, explains Yossi Yovel, a neuroecologist at Tel Aviv University and co-author of this study. “The fact that plants are making these sounds opens up new avenues of opportunity to explore the communication techniques and espionage in nature“adds the expert.

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