Study shows plants emit sounds when stressed

Tobacco Leaves growing in Valle de Vinales, Cuba to be turned into Cigars.
Photo credit: Getty

The idea of people screaming when they are stressed is not that strange.

The thought of plants doing the same things, however, might not seem so normal.

But according to a new study, that just might be the case for some species.

The revelation came after researchers at Tel Aviv University, in Israel, recorded ultrasonic sounds - impossible to hear for humans - coming from tomato and tobacco plants.

The plants emit the sounds when they are stressed by a lack of water or when their stem is cut, the study showed.

The researchers placed microphones 10 centimeters from the plants which picked up sounds between the range of 20 to 100 kilohertz.

The sounds could be heard by many animals or insects coming within three to five metres of the plants, the researchers said.

"These findings can alter the way we think about the plant kingdom, which has been considered to be almost silent until now," the authors wrote.

One example of how animals or insects might react to the sound, the researchers hypothesised, was a moth deciding against laying its eggs on a plant that showed stress from lack of water. It may even be possible that nearby plants could also perceive the sounds and react accordingly, the said.

The authors went on to say that the discovery could "open a new direction in the field of precision agriculture", by offering a "novel way for monitoring crops' water state".

Such potential would be increasingly important as climate change leads to more areas being exposed to drought and human population and consumption rise, they wrote. 

The results could also extend to other species of plants.