The Secret Cries of Stressed Plants
Although many studies have been done on the effect that music and sound have on plants, only recently has the field of bioacustics begun to show how plants actually emit sounds of their own. When faced with stressors like dehydration or physical damage, plants begin to vibrate and produce sound waves. These noises are generally at frequencies too high for human hearing, but research biologists have developed methods to detect these sounds remotely. Lilach Hadany, a biologist from Tel Aviv University, along with her team, has successfully recorded these plant noises, as detailed in their publication in the journal Cell.
Hadany and her colleagues are pioneers in the emerging field of plant bioacoustics. It's been established that plants actively engage with their environment, such as by releasing defensive chemicals. However, their ability to produce and respond to sound remains largely unexplored. Unlocking this mystery could offer farmers innovative tools to monitor crop health, improve our understanding of plant sensory abilities, and deepen our spiritual connection to nature.
Tuning into Plant Noises
According to František Baluška, a researcher at Bonn University not involved in the study, it's a known fact that stressed plants generate more sounds. Previous studies necessitated very close proximity to detect plant vibrations, but Hadany’s team detected these noises from a greater distance. They conducted experiments on tomato and tobacco plants, subjecting some to drought conditions while ensuring others had ample water. Severance from roots was another stressor used. While well-cared-for plants thrived, the stressed ones produced distinct clicking sounds at regular intervals.
Walking through a dry tomato field with a machete won't result in a symphony of plant cries, however. Because these sounds fall within the ultrasonic range, undetectable by human ears, innovations in technology were necessary to make these sounds discernible to researchers. Daniel Robert, an ecologist from the University of Bristol, points out that not everyone has the tools for ultrasound or the inclination to explore these higher frequencies. Many question remain unasnwered. Like, what is are these communicative abilities for? Are plants communicating with each other? Or simply emitting stress signals that have some other purpose? Recent research on bioacoustics will hopefully inspire other scientists to create new experiences that uncover this mysterious form of communication.
Stress-Induced Plant Symphony
The researchers noted similar sounds in other water-deprived plants like wheat, maize, wine grapes, and cacti. It is thought that these sounds might originate from the xylem, the vessel transporting water and nutrients through plants. Pressure fluctuations cause air bubbles to form and burst, producing sounds identifiable by scientists. This phenomenon is known as cavitation. Traditionally, cavitation studies have been the realm of physicists and engineers, as cavitation can be problematic by damaging mechanical components. However, this process is useful in applications like ultrasonic cleaning. Even though cavitation is known to occur in stressed plants, it may not entirely explain all the plant sounds detected. "There might be more than one mechanism at play," suggests Robert.
Hadany's team speculate that their findings could aid plant growers. By using this technology, growers could monitor plant health remotely, receiving alerts before visible symptoms like wilting appear. They have even trained a machine learning model to interpret the sounds and determine the stress type causing them.
"If there is a discernible quality like sound in nature, some organisms will evolve to utilize it" -Daniel Robert
Robert proposes that animals might already detect plant sounds. Insects might use these noises to choose suitable plants for landing or egg-laying.
Can Plants Perceive Sounds?
Some researchers propose that plants might react to external sounds. Baluška's research indicates plants can "hear," with some leaf structures responding to the vibrations of grazing worms. In lab settings, some root tips have been observed growing toward sound sources. This suggests plants may possess more advanced sensory capabilities than previously thought.
"Plants must be aware of their surroundings to respond to constant environmental changes," Baluška concludes. "They need to somehow interpret their environment."
In summary, while plants may lack traditional ears or voices, they have much to 'communicate.' Unraveling their hidden acoustic world could transform botanical science and deepen our appreciation for these silent yet lively organisms.
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Mike: Thank you for this very interesting article. I remember reading about Backster’s experiments in a book titled A Language Older than Words by Derrick Jensen.
The story of Cleve Backster is a very interesting one. Which also delve into researching the hidden unexplored indicators of plants. A book titled Primary Perception was written by Cleve Backster as well which describes many of his experiments.
https://www.sandiegoreader.com/news/1982/nov/24/cover-the-backster-experiments/
Mike D.
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