Worms and Flowers

Talkin’ to Plants: Good Vibrations

Posted in Scientific by Lzyjo on July 16, 2009

Over the weekend I read a post from Gururaj at the Japanese Garden about what his cuttings are saying about him, in particular, he mentioned that his curry leaf cuttings were depressed by the strange lack of ambient street noise, since moving to Japan from India. These thoughts really struck me, it was only last Friday that I threatened my hyacinth bean. With strong intentions I thought to myself, “You Hyacinth bean, you had better flower, or I am going to award you with slow-poke of the year award.” That very same day, in the afternoon, the flowers had popped open!!

We ‘ve all heard the old adage, talking to your plants may help them grow. We’ve also heard things about plants having feelings and enjoying music. I am not disputing that plants are alive, after all, we can watch them growing, but it’s the stuff that happens on the molecular level that really puts a funk in all these arguments about plants having physical feelings.

The notion that plants have a sense of feeling has been around since 300 B.C. Greek  biologist and metaphysicist Theophrastus was one of the first to note the physical response of plants. Darwin, also mentioned this phenomenon when studying the roots of sprouting broad bean seeds (that’s fava beans to us Americanos. ) This work can be found in Darwin’s book The Power of Movement in Plants.

The tendrils of vining plants like clematis, peas, and cucumbers are a great example of a plant’s sense of feeling. When the tendril “feels” support it modifies the growth of the tendril, stopping growth were there is contact and increasing growth in the other parts to quickly and tightly wrap around the support.

In 2004 MythBusters tested the talking to plants to increase growth hypothesis. Despite a malfunction with the experiment’s irrigation system and problems like germinating peas in midsummer on an L.A. rooftop, they concluded that it was indeed plausible.

First it should be mentioned that there have been numerous studies showing correlations between high levels of atmospheric CO2 and relative growth rate. This is a natural defense mechanism. If there is a catastrophic natural disaster, such as a forest fire, the plants usually temporarily increase their relative growth rate and  photosynthesis before becoming acclimated to the CO2-heavy environment.

To eliminate a CO2 response, MythBusters recorded their positive and negative talking. In the experiment there were seven greenhouses, two of positive talking, two of negative talking, a death metal greenhouse, a classical music greenhouse, and the control.

Their results showed the positive and negative talking being equally effective, while the classical music performed better, and best of all were the plants from the death metal greenhouse.

Researcher’s from South Korea’s National Institute of Agricultural Biotechnology have found two genes controlling plants’ response to light were also turned on by music played at 70 decibels. The Korean researchers found differing responses depending on the frequency of the sound. The higher the frequency, the more active was the gene response. A Canadian paper showed that seed germination is influenced by sound at 92 decibels—much louder than one would normally speak.

More from this PennState article can be found here.

Form these various experiments we can conclude that the vibrations of  sound waves trigger Thigmorphogensis, a response plants have to wind, physical touch, and sound, which makes the plants produce ethylene that in turn slows down the upward growth of plants, making them sturdier and stronger to withstand the wind.

In conculsion, neither whispering doting words of affection, nor breathing down your plants neck will increase their overall growth, but turning on the fan, or turning up the stereo just might help to grow a stronger plant!