Mum’s the word.
Thirsty or stressed plants emit popping sounds undetectable to the human ear, in line with research published Thursday within the journal Cell.
Tel Aviv University scientists used special microphones to record ultrasonic sounds produced by tomato and tobacco plants inside a sound-protected box and a greenhouse.
The researchers say they developed machine learning models to discover the condition of the plants, including in the event that they were dehydrated or diseased, based on the detected sounds.
“From previous studies we all know that vibrometers attached to plants record vibrations. But do these vibrations also change into airborne soundwaves — namely sounds that will be recorded from a distance? Our study addressed this query, which researchers have been debating for a few years,” study coauthor Lilach Hadany said in an announcement.
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 main target, but wheat, corn, cactus and henbit were studied as well.
“Before placing the plants within the acoustic box we subjected them to varied treatments: some plants had not been watered for five days, in some the stem had been cut, and a few were untouched,” Hadany said.
“Our intention was to check whether the plants emit sounds, and whether these sounds are affected in any way by the plant’s condition. Our recordings indicated that the plants in our experiment emitted sounds at frequencies of 40-80 kilohertz.”
The utmost frequency detected by a human adult is about 16 kilohertz.
Researchers found unstressed plants typically emitted lower than one sound per hour, while plants that were dehydrated and injured produced dozens of sounds every hour.
The team noted the clicks might be detected even when the plants were placed in a loud greenhouse.
“We assume that in nature the sounds emitted by plants are detected by creatures nearby, reminiscent of bats, rodents, various insects, and possibly also other plants — that may hear the high frequencies and derive relevant information,” Hadany said.
“We consider that humans may utilize this information, given the proper tools — reminiscent of sensors that tell growers when plants need watering.”
Hadany quipped: “Apparently, an idyllic field of flowers could be a somewhat noisy place. It’s just that we will’t hear the sounds.”
Scientists not involved in the brand new research caution there is no such thing as a evidence sounds produced by plants are a type of communication.
“This result adds to what we learn about plant responses to emphasize. It’s a useful contribution to the sector and to our general appreciation that plants are responsive organisms able to sophisticated behaviors,” Richard Karban, a professor who studies interactions between herbivores and their host plants, told CNN.
“Nonetheless, it shouldn’t be interpreted as showing that plants are actively communicating by making sounds,” Karban added.
