TEL AVIV (Sputnik) - Scientists knew that plants communicate with each other when they are under stress, but what was not known before is that they do so with sounds, research from Tel Aviv University (TAU) in Israel reported this week.
"We finally proved that plants make sounds!" said Professor Lilach Hadany of TAU's Plant Sciences and Food Safety faculty, co-leader with Professor Yosi Yovel of the study, which was published in the journal Cell.
"Our findings suggest that the world around us is full of sounds coming from plants and that these sounds contain information, for example, about water shortages or injuries," she added.
It is known that plants can change their appearance, for example, by wilting or changing the color of their leaves, can secrete a more bitter taste to deter herbivores or increase the concentration of sugar in their nectar to attract pollinators, and even emit odors to communicate with family members to warn them that they are being attacked by insects. But this is the first time that sounds from stressed plants have been recorded and classified.
Noisy fields
The researchers revealed that the sound of plants is like a clacking sound, and the volume is similar to that of human speech, but at high frequencies (20 to 150 kHz) that are beyond the hearing range of humans.
"We assume that in nature, the sounds emitted by plants are detected by nearby creatures, such as bats, rodents, various insects and possibly also other plants that can hear the high frequencies and obtain relevant information," Hadany explained.
The authors of the study point out that humans can also use this information from plants with the right tools, such as sensors that translate to growers when plants need watering, for example.
They talk to each other so much that Hadany points out that "an idyllic flower field can be a pretty noisy place. It's just that we can't hear those sounds."
Different languages too
The research team recorded ultrasonic sounds emitted by tomato and tobacco plants that had been deprived of water or suffered a stem cut.
"Unstressed plants emitted less than one sound per hour, on average, while stressed plants, both dehydrated and injured, emitted dozens of sounds every hour," Hadany reported.
Tomato plants, for example, made very little noise when watered, but over the next four to five days, the amount of sounds increased as the plants dried out.
To further test their findings, the team also recorded other species that also emitted sounds, such as wheat, corn, Cabernet Sauvignon grapes and others. Thus, they concluded that plants not only 'speak' but have different 'languages'.
And if the plant world is this noisy, it means that the animal world hears it and reacts to the noises, since ultrasonic range sounds from 20 to 100 kHz can be detected from a distance of three to five meters (10 to 16 feet), indicating that many mammals and insects, such as mice and moths, with their high auditory sensitivity, are attentive to the language of plants.