Jesse, Ithaca asked:
I've heard that talking positively to plants makes them grow better. Is there any good scientific evidence for or against that claim?
Chris - The answer is probably not. But I did a bit of poking around, in fact we have covered a story on the Naked Scientists a couple of years ago by Scientists (the reference is Meh Jong Jong) who is a crop researcher over in South Korea. And published this in the journal of Molecular Breeding. So itís a peer reviewed journal but I'm not sure how robust the science is. But what they did was to, for some reason - and they donít say why in their paper, they were playing classical music to different plants. And they tried 14 different types of classical music to see what effect this would have on the plant growth. And the plants, not surprisingly, did not respond at all.
So then they thought well perhaps itís a mixture of tones and perhaps plants are sensitive to a range or specific set of tones. So then they started playing sounds at specific discrete frequencies at plants and monitoring gene expressions. So they would grind up the plant and see which genes have been turned off or turned on in response to the presentation of a tone over a period of time. When they played certain plants a tone at 50 Hz, a series of genes went down, turned off. When they played the same species of plants some sounds of 150 Hz, 125 Hz or 250 Hz, the same genes increase their activity. And when they use the molecular machinery, the bits of genetic sequence that turned those genes on and off and link them to another gene, that made the cells change colour, thatís called a ďreporter geneĒ they could, by playing certain sounds to the plants, get these plants to change colour. Suggesting that plants are are sound sensitive, so maybe in the case of cereals we know they have ears, so maybe they are sensitive to sounds and therefore maybe, there is some validity in saying you should talk at them. I think itís more likely though, that the CO2 that you are emitting in your breath when you talk to your plants is going to have a bigger effect than the range of frequencies. But maybe Blokeís voices being more low frequency dominate it would have a better effect than womenís voices, I donít know.
Diana - So, Prince Charles was right then?
Chris - Maybe Prince Charles is right, maybe.
Dave - Are plants vibration sensitive? Because when wind blows past them theyíll vibrate, and if itís windy then theyíre going to want to have all sorts of different settings, than if itís not..
Chris - Yeah, plants definitely response to being moved around. Because they realize that this is bending them and they therefore need to strengthen and so they deposit more growth related products and then they turn on growth related genes in the other side of the stem to the one in which they are bending. So they strength from the side that they are bending away from. So in other words, it makes it stiffer on that side. And thatís why trees can look a little bit bent but still stand up despite say an on shore breeze or something. So thatís why.
Jesse asked the Naked Scientists: Dear Naked Scientists, I love your show, and listen to it every week. Here is a question: I've heard that talking positively to plants makes them grow better. Is there any good scientific evidence for or against that claim? Thanks, Jesse Ithaca, NY, USA What do you think? Jesse , Fri, 7th Aug 2009
Breathing CO2 on a plant may have a small, small difference but what really happens is that people talking to their plants give them more care and attention generally. Make it Lady, Fri, 7th Aug 2009
I suspect MIL is about right.
Scientists have discovered some sound-sensitive genes in plants that, they suggest, can modulate gene expression in response to the presence of certain audio frequencies; suggests that wheat really does have "ears"!
From an episode of mythbusters a while back, they played different types of music to plants. Their control tests grew at a normal rate, and those with additional noise grew faster. From memory, rock music was the most successful; I'm assuming this is because of an increase in the noise. Classical was the least successful of all the music. Laura_Kelly, Mon, 17th Aug 2009
Actually, I stumbled upon this while trying to find sources for a lab report I'm writing. I just finished conducting an experiment like the one mentioned above. I bought 3 identical plant (well...as near as I could come to identical)and yelled and screamed at one, sang and spoke nicely to the other and ignored (aside from watering) the other. They all stayed in the same place except when they were getting their 'treatment' so that no other factor could come into play. Although I did feel crazy, the one that got yelled at kept wilting afterwards, even though it grew at a similar rate. All in all, the one we sang to did only slightly better. The one that grew the least was the one that got ignored...weird. Lily, Sat, 4th Dec 2010
I just helped my daughter conduct this test to see if positive language vs. negative language had an effect on plant growth for a school science project. We grew 3 pots of snap beans (2 beans per pot) in equal soil levels, receiving equal sunlight (all next to each other on the same window sill) and receiving equal water (3 tbsp / day). The plants sprouted from the soil on day 6 and the testing began. One plant was used as a control (not spoken to) one was spoken to with sweet, positive language, and the third was screamed at with harsh language, each test plant receiving 5 minutes of conversation per day at night, when removing them from the window sill would not be robbing them from sunlight.