Plants Let Out ‘Ultrasonic Scream’ When Their Stems Are Cut
When you cut yourself or stub your toe, chances are you let out a screech of expletives. However, did you know that plants squeal too?
That’s according to a new study from Tel Aviv University in Israel, which discovered plants emit a high-frequency, ultrasonic scream in distress.
Previous studies attached recording devices directly to the plants allowing researchers to listen for secret sounds inside their stems – but this study looked to ascertain whether their noises can travel through the air.
Using ‘stressed’ tobacco and tomato plants, researchers placed microphones next to them at a distance of around four inches (10cm). One set of crops was subjected to drought conditions, the other endured physical damage, aka snipping their stems.
In both cases, they found the plants began to emit ultrasonic sounds between 20 and 100 kilohertz – not a frequency us humans could pick up on without assistance, but a volume that could feasibly ‘be detected by some organisms from up to several meters away’ according to the study, published on the bioRxiv database.
Tomato plants that had their stems cut let out around 25 ultrasonic screams every hour, while tobacco plants undergoing the same damage let out 15 distress squeals.
However, what’s interesting is how the plants exhibited different levels of stress depending on the subjected conditions: starvation appears to be the catalyst for much more intense cries in tomatoes.
Drought-stressed tomato plants emitted about 35 ultrasonic squeals every hour, while tobacco plants only let out 11. And it’s not a coincidence either: plants that were left untouched, without any adverse environmental conditions, let out less than one squeal every hour, as per Live Science.
Summarising their findings, the group wrote:
These findings can alter the way we think about the plant kingdom, which has been considered to be almost silent until now.
The authors of the study even suggested a future in which farmers are able to identify different plants based solely on their screams alone. With the assistance of machine learning, the researches picked out distinct features of every sound and placed them into three categories: dry, cut or intact.
There are some caveats: the researchers’ scope was quite limited, in that they haven’t looked at the impact of disease, excess levels of salt or unfavourable temperatures on plants – therefore it’s still unknown if they all squeal in distress.
Puts a psychotic spin on doing your gardening, doesn’t it?
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