Natures wonders: plant signals when stressed (Introduction)

by David Turell , Saturday, December 07, 2019, 21:48 (1811 days ago) @ David Turell

They can squeal at a level we cannot hear when stressed, among other abilities:

https://www.livescience.com/plants-squeal-when-stressed.html?utm_source=Selligent&u...

"plant sounds are too high-frequency for us to hear them, according to the research, which was posted Dec. 2 on the bioRxiv database. But when researchers from Tel Aviv University in Israel placed microphones near stressed tomato and tobacco plants, the instruments picked up the crops' ultrasonic squeals from about 4 inches (10 centimeters) away. The noises fell within a range of 20 to 100 kilohertz, a volume that could feasibly "be detected by some organisms from up to several meters away"

"Like animals, plants respond to stress in a variety of ways; studies suggest that plants may release smelly chemical compounds or change their color and shape in response to drought and bites from hungry herbivores. Animals seem to recognize and respond to these botanical stress signals, and even other plants appear to pick up on the airborne scents wafting from their tense neighbors. Some previous research had suggested that plants react to sound, too, but questions remained about whether plants themselves emit detectable noises.

"The recordings revealed that the different plant species made distinct sounds at varying rates, depending on their stressor. Drought-stressed tomato plants emitted about 35 ultrasonic squeals per hour, on average, while those with cut stems made about 25. Drought-stressed tobacco plants let out about 11 screams per hour, and cut crops made about 15 sounds in the same time. In comparison, the average number of sounds emitted by untouched plants fell below one per hour.

"In this study, the authors did not test whether plants exposed to disease, excess levels of salt or unfavorable temperatures also emit sound, so it remains unknown whether all stressed plants squeal. However, the researchers did record similar sounds in other cut or drought-stressed plants, including spiny pincushion cacti, and henbit deadnettle weeds. Insects, such as moths, may listen for sounds emitted by stressed plants to assess their condition before laying eggs on their leaves, the authors suggested.

"Until the scientists observe how and whether moths react to plant noises, this conclusion remains speculative, the authors added — in fact, one outside expert said the idea may be a "little too speculative."

"Edward Farmer, a professor of plant molecular biology at the University of Lausanne in Switzerland, told New Scientist that insects are known to favor certain plants for a variety of reasons and that he doubts excessive noise is one of those reasons. Furthermore, the new study failed to account for sounds that drying soil may make on its own, as well as other confounding noises that the researchers' microphones may have picked up, Farmer added. "

Comment: No explanation of how sounds are made. All organisms need defenses and I am sure they are designed into the organisms DNA instructions.