The fact that the kingdom of flora is much more complex than it seems has long been known. In recent years, scientists have discovered that plants hear the approach of pollinating insects, warn each other of danger, and even know how to count.
But this, as it turned out, is not all the surprises that the flora hides. Recently, specialists from Tel Aviv University recorded for the first time the sounds that a plant makes under stress.
Itzhak Khait and his colleagues found that tomatoes and tobacco, due to lack of water or after cutting the stems, beep. True, the human ear is unable to hear the frequencies at which plants "speak".
Let us explain that Chait specializes in the study of plant life. The researcher has been engaged in molecular biology and ecology for several years. In his experiment, the scientist placed microphones 10 centimeters from the landings. The sensitive equipment detected vibrations in the ultrasonic range (from 20 to 100 kilohertz).
For the first time, scientists were able to record the sounds made by plants at a fairly large distance - about ten centimeters.
The experiment showed that in conditions of insufficient watering, tomato bushes emit an average of 35 "screams" per hour, and tobacco - 11.
A similar reaction was observed when cutting the stems. A “trimmed” tomato produced an average of 25 sounds per hour. Tobacco sounded a little more often than during drought - an average of 15 times per hour.
According to the observations of Hait and his colleagues, the “scream” also differed in intensity depending on the situation. For example, dehydrated tobacco plants made louder sounds than cut ones.
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All this scientists have found out thanks to artificial intelligence. A special algorithm was taught to recognize the intensity and frequency of vibrations emanating from green test subjects and to distinguish them from rustling leaves, the sounds of rain, wind and other greenhouse noises.
How exactly do plants make sounds? Previously, experts using sensors located directly on the stems registered vibrations arising from the so-called cavitation (the formation and explosion of air bubbles inside the xylem).
Let us explain that xylems are plant analogues of vessels, the main task of which is to deliver water and nutrients from the roots to the leaves.
Chait and colleagues suggest that the sound effects they identified may also be associated with cavitation. However, even if the experimenters' guess is correct, so far no one has been able to register such noises at such an impressive distance from plants.
The phenomenon, discovered by Israeli experts, may have a deep biological meaning. For example, insects perceive ultrasonic waves well. Therefore, having heard the "cry for help", some species of moths may refuse to lay eggs on the "dysfunctional" plant.
In addition, the green cousins of the plant in distress are likely to be able to "hear" the alarm signal about the lack of water and even take measures for their own survival, biologists believe.
In a preprint for a scientific article on bioRxiv, the authors argue that their experimental results will help change the way the plant kingdom was hitherto considered "silent."
By the way, Khait and his colleagues are sure that not only tomatoes and tobacco “report” trouble. In preparation for the next scientific project, scientists have already recorded ultrasonic vibrations emanating from a cactus from the genus Mammillaria, as well as a cephalic beetle.
According to the authors of the work, the discovery made by them can become a new page in agriculture. By listening to crops, farmers will anticipate potential water shortages and prevent future crops from drying out.
However, this opinion also has opponents: some colleagues of Israeli biologists believe that it is too early to draw conclusions about the applicability of the phenomenon they discovered in agriculture.
Further research needs to be done to determine if plants respond similarly to other important environmental factors, such as uncomfortable temperatures and soil composition.
Ksenia Vasilieva
