(CNN) Plants make a pop Sounds that are undetectable to the human ear, according to recordings made in a new study They make more sounds when thirsty or under other types of stress.
Search shakes something more Botanists They thought they knew about the plant kingdom, which was considered largely silent, and suggests that the world around us is a cacophony of plant sounds, said a co-author of the study. Your night is my limit.
She said she had long suspected that plants were completely silent.
“There are a lot of organisms that respond to sound, and I thought there was no good reason why plants should be deaf and dumb,” Hadani said. Professor in the College of Plant Sciences and Food Security and Chair of the George S. Faculty of wise life sciences at Tel Aviv University.
The first plant Hadani recorded, using an ultrasonic microphone, was a cactus in her lab six years ago, but she couldn’t rule out that the sound she detected was caused by something else in the environment. Previous studies showed that plants emit vibrations, but it was not known if these vibrations became airborne sound waves.
To see if plants already As she was making sounds, Hadani and her team commissioned the soundproofing acoustic boxes.
The researchers put tobacco and tomato plants into the prepared boxes With ultrasonic microphones that record at frequencies between 20 and 250 kHz. (The maximum frequency that an adult human ear can detect is about 16 kilohertz.) It has not been watered for five days, and others have not been touched.
The team found that plants make sounds with a frequency of 40 to 80 kilohertz, and when amplified and translated into a frequency humans can hear, the sounds were slightly similar. To the pop of popcorn being made or the bursting of bubble wrap.
A stressed plant makes about 30 to 50 of these popping or clicking sounds per hour at seemingly random intervals, but unstressed plants make much less—about one per hour.
“When the tomatoes are not pressed at all, they are very quiet,” Hadani said.
The team conducted the experiments in a greenhouse and placed the plants in soundproof boxes.
Do plants communicate? Not so fast
Researchers don’t know exactly how the sounds are made, but they think the noise comes from cavitation—a process in which an air bubble in a plant’s water column collapses under some kind of pressure, making a click or pop.
But rest assured, the bouquet of cut flowers in your vase isn’t screaming at you in pain. There is no evidence that the noise from the plants is intentional or form of communication.
Richard Karpan, Distinguished Professor of Entomology at UCLA, said, Davis, who studies the interactions between herbivores and host plants. He was not involved in the research.
“However, this should not be interpreted as showing that plants actively communicate by making sounds,” Karpan added.
Sensory ecologist Daniel Robert, professor of biology at the University of Bristol’s School of Biological Sciences in the UK, said that while plant sounds are a passive phenomenon, other organisms may be able to use plant acoustic signals for their own benefit. He was not involved in the research.
For example, he said, the sounds could signal to a moth the message that a particular tomato plant is in stress and is not suitable to lay eggs on or feed on.
“A lot of sounds are being created in the world that are not ‘intentional’ signals, but that can nonetheless be heard by other organisms and used for their own interests. So the concept of communication is really a challenge… does it have to be bi-directional to work and be considered as such?” he said via email.
The study’s lead authors are Yossi Yovel, left, and Lilac Hadani. Both are professors at Tel Aviv University.
Who is listening?
The team repeated the experiment with tobacco and tomato plants in a noisier greenhouse environment. After recording the plants, the researchers created a machine learning algorithm that could differentiate between unstressed plants, thirsty plants, and stunted plants.
“The finding that there is information in acoustic emissions, using neural network classification, is exciting as such (a) technique is fast and can identify data structures that human eyes or ears cannot,” noted Robert.
While the researchers used tobacco and tomato plants because they are easy to grow in a uniform way, they also recorded the sounds made by a variety of other plant species, such as wheat, corn, cacti and grapevines, and also found that they made more sounds when compressed.
In addition to insects or mammals that might detect and use plant sounds, Hadani said other plants can also listen for and make use of sounds. Previous work by Hadani and other team members showed that plants increase the concentration of sugar in their nectar when they “hear” sounds made by pollinators.
Hadani said she now looks at plants and flowers differently. “There are many songs we can’t hear.”