Scientists discover that plants can actually "talk"?

Poplar leaves rustle when wind blows through them, and ripe bean pods rustle when shaken, but can plants make any sounds themselves?

In April 2023, researchers at Tel Aviv University in Israel published a paper that overturned everyone's cognition, saying that plants will make more sounds when they are under stress, but the unique sounds made by plants are of a high frequency, beyond the hearing range of the human ear. What do the sounds made by plants mean?

Generally speaking, our human ears can distinguish sounds with frequencies between 20-20,000 Hz. Infrasound with vibration frequencies below this range and ultrasound with vibration frequencies above this range cannot be received by our ears. Therefore, we usually cannot hear the sounds of plants.

So how did scientists prove that these sounds were made by the plants themselves? To avoid interference from background noise, the experimenters placed the plants in a basement without background noise, and placed tobacco and tomato plants. An ultrasonic loudspeaker was placed about 10 centimeters away from each plant to record the sound.

Analysis of the recordings showed that the plants emitted sounds with a frequency of 40,000 to 80,000 Hz (the highest frequency that an adult can hear is about 16 kHz). Scientists also found that when plants lack water, the number of sounds they make increases significantly, from once per hour to dozens of times per hour. This study expands our understanding of plant senses. Plants can not only release specific chemical components to communicate, but also communicate through sound.

Our first impression when seeing this information is whether plants can talk. It should be noted that making sounds and talking are not the same thing. As mentioned at the beginning of the article, wind blowing through leaves can also make sounds, but this is obviously not a conversation.

There have been some videos saying that plants that receive praise can grow luxuriantly, while plants that are verbally attacked will wither. However, those videos are not experiments in the strict sense. If they are only operated with two pots of plants, they do not reach the minimum sample size required for scientific experiments (30 is a small sample), and they also fail to ensure that the environment (water, light, air) of the two pots of flowers is exactly the same. Even if these factors are excluded, how can plants understand the meaning of human language? In fact, between different groups of people, not to mention the barriers to language communication, even the meanings expressed by facial expressions and gestures are different. There are still barriers to information transmission between people, so how can people and plants achieve seamless communication?

So, what is the use of understanding plant sounds for us? In fact, it is very useful, because after understanding the relationship between plant sounds and the environment, we can monitor the health of crops in real time, and adjust the supply of water and fertilizer in real time according to the sound conditions, so that crops can obtain better growth conditions.

Plants can make sounds, and they can also hear sounds. In Xishuangbanna, there is a plant called Dancing Grass. When music is played, its small leaves will dance up and down, as if dancing to the beat of the music. So far, researchers have found that sound waves can stimulate the cells of Dancing Grass to absorb and release water, so the dancing appearance appears.

The swaying of the dancing grass does not seem to have a specific meaning, but when the evening primrose hears the sound of a specific visitor, it will prepare specific delicacies.

In their study, researchers found that by exposing evening primrose flowers to a series of sounds, including recordings of bees and artificial sounds, and then collecting nectar from the evening primrose before and after the sounds were played, the sucrose content in the nectar of the evening primrose that "heard" the sounds of the bees would increase by 20%. This is truly "good wine to welcome relatives."

In fact, today we still know very little about plant perception, because the range of human senses is very limited. Whether it is our hearing, vision, or smell, there are great limitations - the eyes can only see visible light, not ultraviolet and infrared; the sense of smell can only distinguish relatively strong odors; hearing can only perceive vibrations within a specific frequency range, and communication between different species may be limited beyond this range. In the future, using various instruments to explore the perception of organisms will greatly expand our cognitive field and better understand the animal and plant friends around us.

This article is a work supported by Science Popularization China Starry Sky Project

Author: Shi Jun

Reviewer: Wang Kang (Director of the Science Popularization Center of Beijing Botanical Garden, Professor-level Senior Engineer)

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.