New research has found that plants are not entirely silent but, rather, emit very high frequency noises when stressed.
Scientists from Tel Aviv University, in Israel, placed microphones 10 cm away from various plants and found that they were able to record sounds from that distance in the frequency range of 20 to 100 kilohertz, much higher than the normal human range of hearing.
They were able to force the plants to make noises by depriving them of water or by cutting their stems. Their findings applied to various kinds of plants.
According to the team, tomato plants made 35 sounds an hour, tobacco plants made 11 sounds when deprived of water. When cut, tomato plants made 25 sounds per hour and tobacco plants made 15.
In total, they tested their theory on four different types of plants: tomatoes, tobacco, pincushion cacti and dead-nettle. All four were found to make the sounds under the same circumstances.
The team believes this could lead to revolutionary new agricultural practices where farmers, equipped with sensitive hearing technology, could actually listen for signs of stress in order to intervene.
At this point, it is unknown why the plants make the noise and whether other plants or insects could hear them. Future research will certainly bring a greater understanding of this new frontier in science.
Source: New Scientist