strange but true
March 30, 2023 | 21:07
Mom is the word.
Thirsty or stressed plants emit clicking noises that are imperceptible to the human ear, according to a study published Thursday in Cell magazine.
Tel Aviv University scientists used special microphones to record ultrasonic sounds produced by tomato and tobacco plants inside a soundproof box and greenhouse.
The researchers say they developed machine learning models to identify the condition of the plants, including whether they were dehydrated or sick, based on the sounds detected.
“From previous studies we know that vibrometers attached to plants record vibrations. But do these vibrations also become airborne sound waves, that is, sounds that can be recorded at a distance? Our study addressed this question, which researchers have been debating for many years,” study co-author Lilach Hadany said in a statement.
The researchers say they put the plants in a box in a basement with no background noise, placing ultrasonic microphones about 10 centimeters away from each specimen.
Tomato and tobacco plants were the focus, but wheat, corn, cacti, and henbit were also studied.
“Before placing the plants in the acoustic box, we subjected them to various treatments: some plants had not been watered for five days, some had had their stems cut, and others were intact,” Hadany said.
“Our intention was to test whether plants make sounds and whether these sounds are somehow affected by the plant’s condition. Our recordings indicated that the plants in our experiment made sounds at frequencies of 40 to 80 kilohertz.”
The maximum frequency detected by an adult human is about 16 kilohertz.
The researchers found that plants that were not stressed typically made less than one sound per hour, while plants that were dehydrated and injured produced dozens of sounds every hour.
The team noted that the clicks could be detected even when the plants were placed in a noisy greenhouse.
“We surmise that, in nature, the sounds made by plants are detected by nearby creatures, such as bats, rodents, various insects, and possibly other plants as well, which can hear the high frequencies and obtain relevant information,” Hadany said.
“We think humans can use this information too, with the right tools, like sensors that tell growers when plants need watering.”
Hadany quipped: “Apparently, an idyllic flower field can be quite a noisy place. It’s just that we can’t hear the sounds.”
Scientists not involved in the new research caution that there is no evidence that the sounds made by plants are a form of communication.
“This result adds to what we know about plant responses to stress. It is a useful contribution to the field and to our general appreciation that plants are sentient organisms capable of sophisticated behaviors,” Richard Karban, a professor who studies interactions between herbivores and their host plants, told CNN.
“However, it should not be interpreted as showing that plants actively communicate using sounds,” Karban added.
