A study published in the journal Science in 2023 revealed that plants, such as tobacco and tomato, emit high-frequency ultrasonic clicks (between 20 and 100 kHz) when experiencing water stress or rapid growth stages. These sounds, inaudible to humans, are picked up by bats and moths that feed on nectar.
Researchers at Tel Aviv University recorded up to 30 clicks per hour in healthy plants, a number that spikes when the plant suffers from drought. The mechanism seems related to the formation and popping of air bubbles in the sap-conducting vessels, a process known as cavitation.
- Stressed plants produce more sounds than healthy ones
- The sound can travel up to 5 meters in quiet conditions
- Some insects might use this signal to locate vulnerable plants
This discovery suggests that plants possess a form of passive acoustic communication that could be harnessed in agriculture to detect water stress before it becomes visible.
Source: Khait, I. et al. (2023). Sounds emitted by plants under stress are airborne and informative. Science.
