Plants use acoustic vibes to find a drink

Listening for a drink.
Listening for a drink.
Image: Reuters/Adrees Latif
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Plants are tuned in to acoustic vibrations, and they can hear when the vibes are good. The roots listen for signals of water to drink, according to scientists.

A new study from the University of Western Australia’s Center for Evolutionary Biology, published in Oecologia on April 5, examined whether plants tune in to sound when seeking water. Plant cognition researchers, led by Monica Gagliano, found that plant root systems travel toward water sources by sensing acoustic vibrations.

In other words, plants respond to the sounds rather than the presence of moisture, as if they can feel sound. The team played water flowing through a sink and a recording of the same sound to common pea plants with roots separated in tubes and examined how the roots responded. The scientists found that root systems did not grow toward the recorded sound but did grow toward the water flowing through a sink. They could distinguish between fake water sounds and the real thing.

“It was…extraordinary and surprising that the plant could actually tell when the sound of running water was a recording and when it was real, and that the plant did not like the recorded sound,” writes Gagliano.

Not only that, when water was available from natural sources—in soil—and was still flowing from the sink, roots grew toward the natural source. This indicates the plant made a choice. “From this we begin to see the complexity of plant interactions with sound in using it to make behavioral decisions,” Gagliano explains.

Until now, it wasn’t clear how plant roots located their water sources when no moisture is in the soil—for example, they will bust through sealed pipes to access the water flowing through them. The researchers believe that plants travel toward water using sonic vibrations initially, but that the roots then make choices, targeting the better source by determining moisture levels.

Their study suggests that soundproofing pipes may protect them from the threat of a tree root invasion, as long as no leaks reveal the water source either.

It also shows that growing things are tuned in, meaning that good sonic vibes might be more important for quality of environmental life than previously considered. Plants could be suffering from effects of acoustic pollution. The scientists emphasized the need for more research on both plant and animal responses to noise, concluding that there’s an ”urgent need to better understand the ecological role of sound.”