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Stressed plants ‘cry’ — and some animals can probably hear them
Microphones capture ultrasonic crackles from plants that are water-deprived or injured.
www.nature.com
I'm now imagining an automated watering system that that starts he wants when my trees start crying.
To eavesdrop on plants, Lilach Hadany at Tel-Aviv University in Israel and her colleagues placed tobacco (Nicotiana tabacum) and tomato (Solanum lycopersicum) plants in small boxes kitted out with microphones. The microphones picked up any noises made by the plants, even if the researchers couldn't hear them. The noises were particularly obvious for plants that were stressed by a lack of water or recent cutting. If the sounds are pitched down and sped up, “it is a bit like popcorn — very short clicks”, Hadany says. “It is not singing.”
Plants do not have vocal cords or lungs. Hadany says the current theory for how plants make noises centers on their xylem, the tubes that transport water and nutrients from their roots to their stems and leaves. Water in the the xylem is held together by surface tension, just like water sucked through a drinking straw. When an air bubble forms or breaks in the xylem, it might make a little popping noise; bubble formation is more likely during drought stress. But the exact mechanism requires further study, Hadany says.