Do plants make sounds? As it turns out – yes! A new study has shown that tomato bushes «scream» when their fruits are picked.
The amazing discovery was made by Israeli scientists. They found that tomatoes can be «under stress» due to dehydration or cut stems and fruits. And then they make sounds comparable in loudness to a normal human conversation.
Of course, these are not screams in the usual sense of the word, but sounds or clicks similar to the way bubble wrap pops. The frequency of the noises is too high for the human ear. Animals hear these sounds perfectly, but humans lack the sound sensitivity, so special equipment is needed.
«Even in a quiet field there are in fact sounds that we do not hear, and these sounds carry information», – says Lilach Hadany, an evolutionary biologist from Tel Aviv University.
Let us note that scientists had earlier recorded ultrasonic vibrations emanating from plants. But now the researchers have obtained proof that the sounds travel through the air.
«Plants constantly interact with insects and other animals, and many of these organisms use sound for communication. So it would be very strange if plants did not use sound at all», – says Hadany.
When do plants «communicate» the most?
The researchers used microphones to record healthy and stressed tomato plants, first in a soundproof acoustic chamber, and then in a noisier greenhouse. The tomatoes were thrown into stress in two ways: by not watering them for several days and by cutting their stems. In the end it turned out that a plant in a state of stress makes from 30 to 50 clicks per hour at seemingly random intervals.
«When tomatoes experience no stress at all, they are very quiet», – continues the study's author.
The researchers note that the types of sounds produced differed depending on the cause of the stress. Moreover, tomatoes are not the only plants that can talk.
«We found that many plants make similar sounds in stressful situations – for example, corn, wheat, grapes, and cacti», – says Hadany.
The exact mechanism of these noises is unclear, but the researchers suggest that it may be connected with the formation and rupture of air bubbles in the plant's vascular system – this process is called cavitation.
China is looking for panda caretakers – why does no one want to look after these cuties? It is still unclear whether plants produce these sounds to communicate with other organisms or just for no reason. But scientists say that the very fact that they exist has great ecological and evolutionary significance.
«Perhaps other organisms evolved to hear these sounds and respond to them, – says Hadany. – For example, for a butterfly that is about to lay eggs on a plant, or an animal that intends to eat a flower, these «voices» may help make a decision».
