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Here's a newly released preview of a study not yet subjected to peer review. Its focus on possible plant signals in response to environmental stress or physical damage is similar to that of the studies cited above. However, this study focuses on plant signals emitted in the form of sounds - specifically ultrasonic sounds.
FULL STORY: https://www.livescience.com/plants-squeal-when-stressed.html
Plants 'Scream' in the Face of Stress
A new study suggests that plants that are stressed by drought or physical damage may emit ultrasonic squeals.
In times of intense stress, people sometimes let out their angst with a squeal — and a new study suggests that plants might do the same.
Unlike human screams, however, plant sounds are too high-frequency for us to hear them, according to the research ... But when researchers from Tel Aviv University in Israel placed microphones near stressed tomato and tobacco plants, the instruments picked up the crops' ultrasonic squeals from about 4 inches (10 centimeters) away. The noises fell within a range of 20 to 100 kilohertz, a volume that could feasibly "be detected by some organisms from up to several meters away," the authors noted. ...
Animals and plants might listen and react to the silent screams of plants, and perhaps humans could too, with the right tools in hand, the authors added. ...
Like animals, plants respond to stress in a variety of ways; studies suggest that plants may release smelly chemical compounds or change their color and shape in response to drought and bites from hungry herbivores. Animals seem to recognize and respond to these botanical stress signals, and even other plants appear to pick up on the airborne scents wafting from their tense neighbors. Some previous research had suggested that plants react to sound, too, but questions remained about whether plants themselves emit detectable noises. ...
The recordings revealed that the different plant species made distinct sounds at varying rates, depending on their stressor. Drought-stressed tomato plants emitted about 35 ultrasonic squeals per hour, on average, while those with cut stems made about 25. Drought-stressed tobacco plants let out about 11 screams per hour, and cut crops made about 15 sounds in the same time. In comparison, the average number of sounds emitted by untouched plants fell below one per hour. ...
Insects, such as moths, may listen for sounds emitted by stressed plants to assess their condition before laying eggs on their leaves, the authors suggested.
Until the scientists observe how and whether moths react to plant noises, this conclusion remains speculative, the authors added — in fact, one outside expert said the idea may be a "little too speculative." ...
FULL STORY: https://www.livescience.com/plants-squeal-when-stressed.html