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Current Affairs

Ultrasonic ‘distress screams’ emitted by plants during stress

Date: 15 December 2019 Tags: Miscellaneous

Issue

Researchers have for the first time found evidence of plants making airborne emission of ultrasound screams when subjected to stresses.

 

Background

The researchers experimented with tomato and tobacco plants and subjected them to two different stresses, drought and cutting of stems.

 

Details

  • The sound contains information that can reveal the state of the plant emitting it.

  • The ultrasound emitted is in the range 20-100 kHz and can be detected from a distance of 3-5 metres.

  • Researchers  speculates that if stressed plants can emit ultrasound, then neighbouring plants should be equipped to hear these distress sounds too.

  • Researchers say that  plants' response to pollinator sounds involves their flowers, but the receptors to ultrasound would be in the vegetative parts.

  • Many moths, which use tomato and tobacco plants as hosts for their larvae, are already known to hear and react to ultrasound at frequencies emitted by the plants and may then potentially avoid laying their eggs on a plant that had emitted stress sounds.

  • The researchers suspect that the sounds are generated by a process called cavitation, where air bubbles form, expand and explode in the xylem causing vibrations.

  • Tomato and tobacco plants emitted ultrasound at different mean peak frequencies when subjected to the two stresses. In general, the two plants emitted sounds at a higher peak frequency when the stem was cut than when under drought.

  • Plants belonging to two different taxa also emitted ultrasound when subjected to the same stresses.

  • Scientists are currently extending the work to additional species and conditions and are also in the process of examining the potential agricultural applications of the findings, which would likely be more diverse than the original research.