Short Wave - Micro Wave: Does Talking To Plants Help Them Grow?

Episode Date: October 9, 2020

Environmental scientist Heidi Appel explains how plants detect sound — and whether talking to yours could help them grow big and strong. Plus, a bit of listener mail from you! Which you can always send by emailing [e-mail]. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

Hey, everybody, Maddie Safai here with Emily Kwong. Hey. So today we have a microwave inspired by a pair of shortwave listeners and your real-life friends, Emily. I do have real friends, yes. Yes, you do, too. Amy Wersberg and Amanda Drury. Yes. Amy and Amanda, like a lot of us, are trying to grow plants.

We have five plants, all our herbs. And every morning as Amy waters the plants, she talks to them. She'll say, good job, sage. Time. I'm really seeing some good growth here. Parsley's looking a little wealthy, but parsley. I believe in you. I wish somebody believed in me as much as Amy believes in parsley. You know what I'm saying, Kong?

Yeah. So why does Amy talk to her plants? Well, she believes that on a chemical level, it helps them grow big and strong. And, yeah, Amanda does not agree. I don't think that talking to plants really makes that much of a difference. So what about the fact that our cilantro is dead because you were mean to it? Well, I don't like cilantro, so either way, I'm fine with it. I'm just saying all the rest of our plants are doing okay except our cilantro.

But I also don't like parsley, and parsley is fine. Honestly, I'm on team parsley right now, Kwon. As you should be. And Amy and Amanda texted me and we're like, Emily, please resolve our couple squabble. is there scientific evidence around the benefit of talking to plants? So is that what our microwave is about today? Plant communication? You better believe it.

Plant bioacoustics. And whether talking to plants actually makes a difference. All right, Emily Kwong, you are here for another microwave. Beep, beep, beep. Short little episodes where we read some listener mail at the end. And we're talking about what science has to say and not say about plant bioacoustics. And this question that I can't believe I'm asking, which is, does talking to plants impact their growth? It is probably the most common question I get from the public.

This is Heidi Apple, professor of environmental sciences at the University of Toledo. And just to get this out of the way, there is no conclusive scientific proof that talking to your plants helps them grow. Oh, all right. There we go. Episode done. Boo, boo, boo, boom, boom. We out of here. Well, hold the phone, suffice. It's not that simple because Heidi is one of the few people who has studied plant response to sound. They have a sense of vision, sight, smell, and taste. And scientists, including Heidi, have found evidence that plants can detect sound too.

All life has some form of mechanoreception. Mechano reception, meaning they can sense stimuli from their environment, like touch, pressure, and vibration. We humans have pressure receptors on our skin, and it turns out that plants can sense pressure too. This is very cool. I'm getting into this now. Yeah. Through these special proteins called mechanoreceptors that can send a signal that sets off a chain of events telling the plant how to respond. So like if a bug lands on them or something? Yes, and the plant will perhaps release a chemical to defend itself. Ooh, plant panic.

That's right. So these mechanoreceptors are really important for telling the plant what's up in its environment. And plant scientists think these mechanoreceptors may play a role in helping plants pick up vibrations, including the vibrations caused by sound. You know, sound waves. We've known for a long time that plants can respond to single tones or even music. And they can respond by growing a little differently or their seeds may germinate at a different rate. But we never understood why they would do this.

Why would they have this capability? And that's where my work with collaborator Rex Codcroft at the University of Missouri comes in. So a few years ago, Heidi and Rex put together a little study asking if a plant will respond to vibrations in their environment. And the vibration they chose to test was caused by a caterpillar chewing. What an adorable experience. experiment. Munching up the leaves of a plant, specifically a mouse ear crests, which Heidi had growing in the lab. And these vibrations are super subtle. The leaf is sometimes moving like one 10,000th of an inch as the caterpillar bites down. Rex and Heidi then played the vibration,

the vibration of the Naman caterpillar, right, back to other crest plants who had not been munched on at all, and then exposed those same plants to real caterpillars and measured their chemical response. And the plants that had heard the recording beforehand produced more insect defense chemicals. Oh, so like playing the sound before the real caterpillar kind of like primed the plants. Yeah, this experiment showed that plants pre-exposed to the sound of a chewing caterpillar produced a different response. More plant panic, if you will. Yes, I will, which suggested, you know, that plants, these plants, are sensitive to the sounds of this predator, the caterpillar. And then they tested other vibrations on the plant, wind, other insect eating noises that were not as threatening.

And when you know, the plants did not respond. Like, chemically, they didn't respond. Correct. So, okay, so does that mean they have, for lack of a better term, selective hearing? More like selective responding. Okay. Plants do respond to sound, but only to sounds they've evolved to respond to, if that makes sense. Yeah, totally.

In this case, a caterpillar chewing. Gotcha. Okay, so caterpillar chewing, yes. But what about a human voice? Well, that hasn't been comprehensively tested. Okay. And Heidi thinks it's not likely. A plant will be experiencing noise in the sense of wind or a calling bird or a singing entomologist.

I don't mean, but they will be tuned to only the things that are important to them. Oh. Right? And we don't know if one of those things is a human voice. We also don't know the threshold of what they detect, and we don't know if they'd have a reason to respond. So should you talk to your plants? Sure, why not? Is it going to help them grow better?

Your voice alone? No, I don't think it's going to. However, if you connect emotionally with your plant better because you're talking with them, that means you're probably going to take better care of it. And therefore, talking to your plants indirectly could be helpful. That's kind of beautiful. I do honestly feel emotionally connected to my plants, Kwong, I'll say it. Did you name them? No, because they're like clones, so I don't want them to get any ideas, like clone one, clone two.

You know what I mean? I try to keep a distance, you know, I don't want to have favorites. Well, Maddie, it's great to hear you're experimenting at home. Because Heidi says there's a lot we could stand to learn about plants. Plants have about 80% of the biomass on Earth, and we are doing a terrible job taking care of it. And the ecosystem services they provide are so important to our long-term survival. So if people can think of plants with more affection and appreciation for what they do, I think we will be much better off as humans. Wow, Kwong, that's kind of beautiful.

So, Amy, you were kind of right. Yeah, kind of. Not that I'm taking sides, obviously. You clearly are. Both my friends. You know both my friends. You know who else leaves us off as better humans, Emily? Ah.

Our dear shortwave listeners. Yes, it is listener mail time, where we read notes from the inbox sent by you. This one is from Stephanie Pevers in Rancho Cucamonga, California. Stephanie writes, I offer extra credit to my sixth grade science class to listen to one of your episodes about once every week or two. If I forget to offer it, many students start clawing at me. The tiny little sixth grade claws. Yeah, based on, I assume, based on your mosquito episode last week, I received this feedback.

If I ever meet this maddy person in real life or in the comments on shortwave or on an email, then tell her to 1V1 me in Minecraft Battle Royale. Oh my God, another Minecraft challenge from a list. I think I need to get into this, call them. The people are calling. Yeah, that's true. Thanks for making distance learning, teaching easier. That's Stephanie in California.

Love it. So good. So good. All right. Next up, we got a ton of listener notes after our episode about the science behind ripening fruit in a paper bag, featuring our one and only producer, Britt Hanson. Oh! Like this one from Kiara Margaria.

And it says, it seems like you forgot to mention. the most famous ripening combo, at least where I am from, Kiwis and apples. You know, the truth is, Britt loves Kiwis too. Yeah. You know that, right? Britt's a fruit universalist. That's true. That's true.

She continues, My father is a Kiwi producer in Italy. We would put boxes of unriped kiwis on top of boxes of apples and let the magic happen. It's like the peanut butter and jelly of fruit. All right. That is it from us. our latest microwave. Thank you to our listeners. And thank you to you, to you, Emily Kwong. Always, Maddie's file. Today's episode was produced by Brent Bachman, edited by Viet Le, and fact-checked by Ariel Isabidi.

Thanks for listening to Shortwave from NPR.