Can talking to plants make them grow faster?
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) in South Korea who published in the Journal of Molecular Breeding.
What they did was to, for some reason - and they don't 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 it's 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, that's called a "reporter gene"; 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!
Therefore, maybe, there is some validity in saying you should talk at them. I think it's 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 Bloke's voices being more low frequency dominate it would have a better effect than women's voices, I don't 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 they'll vibrate, and if it's windy then they're going to want to have all sorts of different settings, than if it's 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 that's why trees can look a little bit bent but still stand up despite say an on shore breeze or something. So that's why.