Plants don't make noise, do they?
Tomatoes could even scream, researchers now say.
It just sounds more like popping popcorn.
Anyone who talks to their plants will not be surprised by this news anyway.
But even skeptics are now getting scientific evidence that plants seem to make emotional sounds.
They may not necessarily make contact with humans, but they are at least audible - at least in the ultrasonic range.
Mammals and insects can hear the sounds of plants
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When tomatoes suffer from heat stress and lack of water, they begin to vibrate.
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The noises are about as loud as a normal conversation, but the frequency of the tones in the ultrasonic range is too high for humans, write scientists from Tel Aviv University in the journal Cell.
Whether the plants produce such sounds to communicate with other organisms is unclear.
Other studies have already shown that plants, for example, increase the sugar concentration in their nectar in response to noises made by pollinators.
According to a study, stressed plants can make a lot of noise - but people don't hear it.
But other creatures do: "The sounds in the ultrasonic range could be heard by many mammals and insects from a distance of three to five meters," the researchers assume.
Plants such as tomatoes and tobacco become noisy when they suffer from drought stress or when their stems are cut, the research team further reports.
They sound a bit like crushed bubble wrap or popping popcorn.
And what if an entire wheat field is about to be harvested?
The scientists explain that crop plants such as corn or wheat also make noises under stress.
"It is therefore likely that noises will also be emitted during harvesting (in the form of cutting)," said Lilach Hadany, an evolutionary biologist at Tel Aviv University, in response to a dpa request.
The team was also able to show that plants such as cacti, vines and dead nettles also make noises.
Benefits for agriculture and your own garden
Some allotment gardeners may feel uncomfortable at the thought of their home-grown vegetables or herbs starting to pop from the stress when they are cut off.
However, it has long been known that plants can also experience stress in other ways, for example when they are too close to other plants and compete with them for light, or when other animals damage them.
To do this, they have developed defense mechanisms such as resistance.
However, the researchers from Israel see a very practical, possible use for agriculture in their findings: With the help of sound recordings, for example, the irrigation of plants in the field or in the greenhouse can be monitored and made more effective.
For the study, the scientists examined tomato and tobacco plants under various conditions.
In one of the experiments, the plants had too little water, in another their stems were cut.
For comparison, the team also looked at undisturbed specimens.
The scientists used microphones to record sounds in a soundproof room and also in a greenhouse.
The result: According to the study, stressed plants emitted significantly more noise than healthy ones.
Under stress, they made around 30 to 50 tones per hour.
"If tomatoes aren't stressed at all, they're very quiet," says Hadany.
Using an algorithm, the team was able to see how the sounds differed depending on the type of stress.
10 plants that take the heat - from flowers to vegetables
10 plants that take the heat - from flowers to vegetables
Drought stress can cause vibrations in tomatoes
The researchers assume that the cause of this phenomenon takes place inside a plant.
Studies have shown that so-called cavitation occurs in plants that suffer from drought stress.
Roughly speaking, air bubbles form in the vascular system, which expand and collapse again.
This leads to vibrations.
"The design of the study is good," says Sibaji Kumar Sanyal, a molecular biologist at Heinrich Heine University in Düsseldorf, who was not involved in the study.
You can quickly understand from the sounds if the plants were not watered properly.
For future studies, however, it is important to examine other plant species in addition to tomatoes and tobacco.
So do people get the wrong idea about quiet nature – when, for example, the domestic houseplants need water again or the vegetables are harvested in the garden?
"That's an interesting idea.
But if you look at the frequency of the plant sounds, it is in the ultrasonic range.
That's why they are still silent for us," explains Sanyal.
Anyone who grows tomatoes in their own garden knows anyway that the plants need a lot of water, especially in hot summers.
But maybe the thought that the tomatoes actually suffer from it in some way will also help to keep it in mind in the future.
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