- The sounds emitted by plants are ultrasonic, beyond the hearing range of the human ear.
- Plant sounds are informative: mostly emitted when the plant is under stress, they contain information about its condition.
- The researchers recorded mainly tomato and tobacco plants; wheat, corn, nopal and henbit were also recorded.
The researchers said:
“Apparently, an idyllic flower field can be quite a noisy place. It’s just that we can’t hear the sounds!”
World breakthrough: For the first time in the world, researchers at Tel Aviv University recorded and analyzed the sounds clearly made by plants. The click-like sounds, similar to popping popcorn, are emitted at a volume similar to that of human speech, but at high frequencies, beyond the hearing range of the human ear. The researchers said:
“We found that plants generally make sounds when under stress, and that each plant and each type of stress is associated with a specific identifiable sound. While imperceptible to the human ear, the sounds made by plants can probably be heard. by various animals, such as bats, mice, and insects.
The study was led by Prof. Lilach Hadany from the Wise School of Plant Sciences and Food Safety, together with Prof. Yossi Yovel, Director of the Sagol School of Neuroscience and faculty member. from the School of Zoology and the Steinhardt Museum of Natural History, and research students Itzhak Khait and Ohad Lewin-Epstein, in collaboration with researchers from the Raymond and Beverly Sackler School of Mathematical Sciences, the Cereal Crop Research Institute and the Sagol School of Neuroscience, all in Tel Aviv. University.
Prof Hadany said:
“From previous studies, we know that vibrometers attached to plants record vibrations. But do these vibrations also become airborne sound waves, i.e. sounds that can be recorded at a distance? Our study addressed this question, which researchers have been debating for many years.”
In the first stage of the study, the researchers placed plants in a speaker box in a quiet, isolated basement with no background noise. Ultrasonic microphones recording sounds at frequencies of 20 to 250 kilohertz (the maximum frequency detected by an adult human is about 16 kilohertz) were installed at a distance of about 10 cm from each plant. The study focused mainly on tomato and tobacco plants, but wheat, corn, nopal, and henbit were also recorded.
Prof Hadany said:
“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. Our intention was to test whether the plants make sounds, and whether these sounds are affected in any way by the condition of the plant Our recordings indicated that the plants in our experiment made sounds at frequencies of 40-80 kilohertz Unstressed plants made less than one sound per hour, on average , while stressed plants, both dehydrated and injured, made dozens of sounds every hour.”
The recordings collected in this way were analyzed by specially developed machine learning (AI) algorithms. The algorithms learned to distinguish between different plants and different types of sounds and were eventually able to identify the plant and determine the type and stress level of the recordings.
Furthermore, the algorithms identified and classified plant sounds even when the plants were placed in a greenhouse with a lot of background noise. In the greenhouse, the researchers monitored dehydrated plants over time and found that the amount of noise they made increased up to a certain point and then decreased.
Prof Hadany said:
“In this study we resolved a longstanding scientific controversy: we proved that plants make sounds! Our findings suggest that the world around us is full of plant sounds and that these sounds contain information, for example about water scarcity. or wound 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, which can hear the high frequencies and obtain relevant information.We believe that humans can also use This information, with the right tools, like sensors that tell growers when plants need watering. On the surface, an idyllic field of flowers can be quite a noisy place. It’s just that we can’t hear the sounds!
In future studies, the researchers will continue to explore a variety of intriguing questions: What is the mechanism behind plant sounds? How do moths detect and react to sounds made by plants? Do other plants also hear these sounds? And more…
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