Plants give out an “ultrasonic scream” when they are stressed

Researchers at Tel Aviv university want to help "precision farming"

Some plants emit a high-frequency distress sound when they experience environmental stress according to scientists at Tel Avi University in a study described in Live Science. The screams are at too high a frequency to be heard by human ears. 

The researchers deprived tomato plants and tobacco plants of water and cut their stems. They then recorded the plants’ responses with a microphone that was ten centimetres away. 

In each case, it was discovered that the plants began to emit ultrasonic sounds between 20 and 100 kilohertz. It was surmised that these were distress sounds that were observable by other plants and organisms nearby.

When the plant stems were cut, the researchers discovered that a tomato plant emitted 25 ultrasonic distress sounds during an hour whereas tobacco plants gave out 15.

In the case of water deprivation, again the tomato plants gave out more distress sounds, 35 in an hour, compared to just 11 in the case of the tobacco plants. 

The intensity of the sounds also varied according to the stress source. 

By contrast, plants that had no immediate environmental threat or damage released less than one ultrasonic sound in an hour.

“These findings can alter the way we think about the plant kingdom, which has been considered to be almost silent until now,’ the group wrote in a paper summarizing their findings. 

The research team were attempting to predict the different frequency of sounds plants might give out in certain environmental conditions such as wind and rain. 

“The suggestion that the sounds that drought-stressed plants make could be used in precision agriculture seems feasible if it is not too costly to set up the recording in a field situation,” commented Anne Visscher at the Royal Botanic Gardens in Kew.

The paper has not been subjected to peer review.

The inevitable argument against veganism….

So hands up those vegans who have had their ethics countered with: “but plants feel pain as well”. 

No doubt someone somewhere will cite this study as grist to the mill for the argument that vegans are hypocrites for eating plants. If plants give out stress squeals when under stress, just like humans or animals, then surely it is hypocritical of vegans to eat plants – at least that is the way the argument goes.

The tomato and tobacco plants, of course, have no brain and no central nervous system. They have no feelings or pain receptors. They are certainly alive and do operate on a cellular level and respond to stimuli as an involuntary action. But plants do not respond like animals. Without a central nervous system, there is no likelihood of sentience in plants in the same way animals experience life.

Most people driving a car will instinctively swerve out of the way if a dog runs across the road, but will not do so if some plants blow across the road. Most people would struggle to slit the throat of a pig but would have no difficulty cutting the stem of a tomato plant.

We do however share DNA with plants. Indigenous populations who live in areas rich in bio-diversity are far more aware of their natural environments than modern man. They may well have a different perspective.

But even if a person believes plants are alive and feel pain to a sufficient degree to make vegans hypocrites, the lack of a central nervous system notwithstanding, there is one cogent argument for that person to take veganism seriously.

It still takes 16 lbs of farm grain to produce just one pound of meat.

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Nicholas Orosz

Nicholas is a former City solicitor and Cambridge graduate. He has a long-standing interest in health & nutrition, the environmental movement, green politics & digital publishing. He has always loved crafting words. His transition to a vegan perspective has been gradual and an ongoing process of self-discovery. Contact:
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