I ricercatori dell’Università di Tel Aviv hanno registrato i suoni che diverse specie vegetali emettono, a una frequenza non udibile dall’orecchio umano. Assomigliano allo scoppiettio del mais nel forno a micro-onde.
When subjected to stress even plants literally ‘complain’. They emit sounds inaudible to the human ear but, in all probability, heard by some animals and plants themselves. These sounds, resemble clicks and, according to a team of researchers from Tel Aviv University (Israel), corn popping in a microwave oven.
It has been known that plants emit vibrations in specific situations for many years, but until now it was never clear whether these vibrations could be translated into sound waves.
To answer these questions, the Israeli researchers subjected the plants (mainly tomato and tobacco, but also cacti, wheat and corn) to various kinds of extreme stress including cutting them or not watering them for 5 days.
They then placed them in special soundproof boxes and, with special microphones that can record ultrasound up to 250 KHz (the highest frequency audible to the human ear is usually only 20 KHz), they separated the stems at a distance of 10 cm.
In this way they showed that plants subjected to stress emitted sounds at 40-80 KHz. The other control plants, left in normal conditions, remained ‘silent’, emitting only around one vibration per hour, while the stressed plants produced dozens in 60 minutes. But that’s not all. Once the stress was removed, the plants slowly began to diminish the quantities of sound waves.
A curiosity about plants: they have an alarm system
The sounds therefore seem to work as an alarm and information system for other plants, and this information is probably also picked up by animals like bats, rats and moths.
This is also suggested by an AI program that has analysed the sounds. It can distinguish between different types of vibrations, decodifying the languages of the sounds emitted in various situations by different types of plants.
The programme is also able to detect and interpret the sounds of the plants in a normal environment and is full of sounds that disturb (like air conditioning) in a greenhouse for example.
The wood is not silent
This discovery, many aspects of which are revolutionary, was described in the scientific journal Cell. The Israeli researchers have also created a video and an mp3 file.
The results of this study suggest new ways of looking at how plants (which have a clear ‘sensibility’) are thought of and treated, and it offers a glimpse of other possible important spin-offs, including economic ones, to optimise cultivation. This might be information on the lack of water or on damage provided by the plants themselves, which could be very useful for farmers.
Furthermore, these studies throw a new light on what a wood or a field of flowers could truly be: an extremely noisy place for those who can understand the frequencies emitted by various plants.
