In new research, biologists at Tel Aviv University recorded ultrasonic sounds emitted by tomato and tobacco plants inside an acoustic chamber, and in a greenhouse, while monitoring the plant’s physiological parameters. They developed machine learning models that succeeded in identifying the condition of the plants, including dehydration level and injury, based solely on the emitted sounds. The frequency of these sounds is too high for human ears to detect, but they can probably be detectable by other organisms such as insects, mammals, and possibly other plants.
Plants show significant changes in their phenotypes in response to stress. They differ visually, with respect to both color and shape, from unstressed plants.
They also emit volatile organic compounds, e.g. when exposed to drought or herbivores. These compounds can also affect neighboring plants, resulting in increased resistance in these plants.
Altogether, plants have been demonstrated to produce visual, chemical, and tactile cues, which other organisms can respond to.
Nevertheless, the ability of plants to emit airborne sounds — that could potentially be heard by other organisms — has not been sufficiently explored.
“Even in a quiet field, there are actually sounds that we don’t hear, and those sounds carry information,” said Tel Aviv University’s Professor Lilach Hadany, senior author of the study.
“There are animals that can hear these sounds, so there is the possibility that a lot of acoustic interaction is occurring.”
“Although ultrasonic vibrations have been recorded from plants before, this is the first evidence that they are airborne, a fact that makes them more relevant for other organisms in the environment.”
In their research, Professor Hadany and colleagues used microphones to record healthy and stressed tomato and tobacco plants, first in a soundproofed acoustic chamber and then in a noisier greenhouse…
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