How plants make noise when stressed

TEL AVIV, ISRAEL — New research from Tel Aviv University has found that plants make noise when stressed.

For the study, scientists focused on tomato and tobacco plants.

They placed plants into three groups. These were drought-stressed plants, plants cut at the stem and control plants. These were placed in an acoustic box for an hour.

Each plant was recorded with two microphones placed 10 centimeters away.

On average, drought-stressed tomato plants emitted roughly 35 ultrasonic sounds per hour, while tobacco plants produced 11 per hour. Cut tomato plants created roughly 25 sounds per hour, while tobacco plants generated 15.

The study found that all control plants produced, on average, less than one sound per hour.

The scientists explained in the study that these sounds could potentially be heard by other organisms up to several meters away.

The tomato plants were also placed in a greenhouse setting to test whether or not sounds emitted by plants would be identified outdoors. The results matched researchers' findings from the plants in the acoustic box in that plants produce more sounds as they become dehydrated.

Machine learning classifiers were able to distinguish distinct noises produced by the different plants in both the acoustic box and the greenhouse setting.

Researchers suggested that in the future, farmers may be able to use this type of technology to listen out for drought-stressed crops to better assess their crops.