Science Friday
Hosted by Flora Lichtman and Ira Flatow
It’s squash, pumpkin, and gourd season. In a conversation from 2023, an expert answers listener questions about these colorful fall favorites.
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Hello, it's Flora Lichtman, and you're listening to Science Friday. 'Tis the season of squash. So today on the podcast, we are bringing you a conversation from the pantry. Ira is celebrating all things cucurbita and fielding your burning squash questions. Let's go.
Now, you can see squash everywhere, right? In this holiday season, you've got those carved pumpkins. They're actually squash, believe it or not. Those giant, award-winning pumpkins are squash, too. How do they get so big? And what's the difference between a gourd and a squash? And how do you breed a better squash? We actually have somebody who knows the answer to all of those things. Dr. Chris Hernandez, Assistant Professor of Plant Breeding at the University of New Hampshire in Durham, New Hampshire. He's Director of the University's Squash, Pumpkin, and Melon Breeding Program. Welcome to Science Friday.
Hi, Ira. Thanks for having me on.
How did you get interested in squash and pumpkin breeding?
Yeah, I suppose it's kind of a different type of profession. But yeah, you know, my dad was really into gardening. He got me into gardening, and I was doing some gardening in a community garden, and there was a guy there growing giant pumpkins. And I just thought that was the coolest thing in the world. And it's what got me started, kind of motivated me to go on and study plant breeding genetics.
I understand this year's world record for pumpkin was nearly 3,000 pounds.
That's right, 2,700.
How do growers get pumpkins to grow so big?
Well, it's nature and nurture. So you need to have the right seeds or the right, you know, the seeds that have that genetic potential. And then you need to have the perfect growing conditions for those seeds, for that plant.
Can I buy seeds and grow my own giant pumpkin?
You could. So the, the variety that, you know, all giant pumpkins are thought to come from is called a Dill's Atlantic Giant. So it was developed by a farmer in Canada in like the 1970s. Um, so you can get that seed, but that's actually not your best bet. So
Oh, no.
Kind of your over the counter seed, um, is not really what growers are using now. They kind of have their own exchange of seeds where there's been selecting and breeding as a community. And so those seeds are kind of what you want to get.
All right. Let's get into some basics here. Pumpkins and squash are part of the cucurbit, the cucurbit family. Is that right? What other plants are included in cucurbits?
That's right. They're cucurbits from the cucurbitacea family is the full name there, but we call them cucurbit. So includes, like you said, squash, pumpkins, melons, cucumbers, watermelons, wax gourds, pretty much all of your binding fruits and vegetables that you know about are, well, they're all fruit. Um, but they're cucurbits.
Cucurbit. I thank you for correcting me on that one. What, what's, so what's the difference between a summer squash, let's say, versus a winter squash?
So that's all about the time that you eat the fruit. So a summer squash you eat at before it's mature, whereas a winter squash you eat at physiological maturity or when the fruit and the seed are completely developed. So it's, you know, eating it at 60 days versus eating it closer to six days after pollination.
Six days? That's all it takes?
Eight days after pollination is a summer squash or zucchini is usually, yeah.
And then the winter squash, you say, takes 60 days. That is a difference.
Yep.
What is the, speaking of differences, what's the difference between a gourd and a squash?
You know, that's actually kind of a contentious, um, it's a bit of a debate among cucurbit scholars, I would say. Uh, if you look at the last five decades, there's a lot of argument about that terminology. Um, so I might be, get myself into trouble here, but I would say, you know, a squash is something that we eat, uh, whereas a gourd is your, a hard shelled ornamental type of squash.
Hmm. Now, I was looking
That's sort of how I define it.
Yeah. I looked this up in Wiki and Wiki, the Wikipedia says that gourds have been found in sites dating back 13,000 BCE.
That's astounding.
So, yeah, the gourds are kind of more of like that undomesticated type. So I think my understanding is as far back as around 10,000 years ago, we were domesticating them.
Crystal in Rochester, New York. Hi, Crystal.
Hi.
Hi there.
Um, I was wondering, so I grow pumpkins myself and like use them to make pumpkin pie and stuff, but one of my friends told me that if you get canned pumpkin, it's actually Hubbard squash. And that that's better to use for making stuff. And I wondered if that was true and if so, why do they use Hubbard squash and why do they call it pumpkin?
Good, good question. Let me, let me ask. Is, is there not pumpkin in a can of pumpkin? Dr. Hernandez?
Not what we would call a pumpkin. So we typically would call a pumpkin like something that looks like a jack lard, right? And that's actually not what you want to eat. You can eat it, but it's the lowest quality, I would say. So, yeah, that's exactly correct. So a canned pumpkin is actually either a Hubbard, which is a different species from the jack lard, or more like a butternut type of squash. So in a lot of other countries, we call, they call eating squash a pumpkin. So.
Now, most of us have gone pumpkin picking, but you've worked on breeding pumpkins specifically for these you pick them up operations, right? What, what are the traits that the you pick farmers are looking for?
Yeah. So, you know, if you ask anyone in the pumpkin business, they'll tell you that they're not in the business of selling fruit. They're in the business of selling a handle. So the, the handle is actually a trait that we focus a lot on. Because if you think about it, you're not going to buy a pumpkin that doesn't have a handle, right? And you also couldn't pick it. If the handle comes off when you pick it up, that's not a good pumpkin. So we put a lot of effort into having a handle with a really good attachment on that pumpkin. And then from there, we look at, you know, different types of colors, sizes. And then, of course, having a pumpkin that's going to grow well for the grower. So it has that disease resistance and the yield potential. But, yeah, the handle gets a lot of care.
Does the handle have a scientific name to it?
Uh, the poduncle.
Now, as you're, as you're growing and designing pumpkins, are there any other decorative pumpkins, uh, gourds? Are there, are there trends going on?
Yeah, I would see, you know, something that I'm seeing now is like a lot of people are liking those white pumpkins. So we're starting to do some work with developing pumpkins that have that white color that stay white. And also I'm seeing a lot more round or stacker type pumpkins, which is a different species than the jack lanner. It's a cucurta maxima. And so I'm starting to look at those now as well.
You know, I think I hear about a story like this every year. Someone throws out a pumpkin in their backyard or into their compost heap. And then you've got a pumpkin patch the next year of all these seeds have sprouted. How likely is this to happen?
I see it all the time. We call those volunteers.
Volunteers. Chris, have you tried that yourself with the pumpkin? Throwing it back?
Growing them in the compost.
Yeah.
You know, not in the compost pile itself, but they will, they do do well if you grow them in kind of a mound of compost. Like if you, that's kind of like if you mound up the soil, that's a good, good for them. They love growing like that.
Now, I know, I know that you're currently breeding acorn squash. What are the traits you try to optimize for?
So with acorn squash, we, like I said, we kind of like those grower traits, which I think of like good disease resistance, you know, earlier. So they get a harvest earlier. And on the quality end, we look at the, the dry matter.
Right.
Which is a kind of a proxy for starch and then also the sugar content or bricks. We actually, we freeze them and then we squeeze them to get that bricks concentration.
Freeze them and squeeze them. I have to remember that about squash. Let's go to Frankie in western Massachusetts. Hi Frankie. Hi there.
Hello.
How's it going?
Fine. Go ahead.
So I was remembering, when I was a kid, I read one of those Little House in the Prairie books called Farmer Boy. And in it, at one point, Almanzo decides to grow a pumpkin using milk. He kind of, he digs a hole in the ground and he puts a bowl of milk there. He puts a string in the bowl, cuts a small hole in the vine of the pumpkin and puts the other end of the string in the vine. And the pumpkin like grows huge. It becomes massive. And it's all supposedly because it's a milk fed pumpkin. And I've done some kind of cursory Googling. I cannot figure out if this is actually something that would work, or if this was some kind of invention of the author.
Chris, have you heard about this?
I have. And I was actually wondering if milk and pumpkins would come up. A lot of giant pumpkin growers have tried using milk and it doesn't seem to help at all. So the idea is the calcium might help with the fruit development.
At least for milk, we don't see that.
Well, thank you, Frankie. That was an interesting question.
Of course. Thanks for the insight.
You're welcome. Chris, what's the biggest challenge to designing new foods here, especially with your squash?
Wow. Yeah, I mean, there are a lot of challenges. What's the biggest challenge? We know with squash and pumpkins, the hardest part is they take up so much space. So it's really hard to have like large populations that you can look through to find what you're looking for. Because they just take up so much space. So that's a challenge that I have. It's also always hard to know, because when you're breeding, it takes six to eight years to get that new variety. It's hard to know what's going to be popular six to eight years out. So that kind of prediction part of it.
Well, before we go to the break, I want to get to Kirk in Portland, who has a really interesting question. Hi Kirk, welcome to Science Friday.
Oh, my gosh. Thank you for taking my call. Hey, I'm a retired science teacher from high school. And I've been having a garden for years and years. And I thought, you know, I'll do what Gregor Mendel did. And I'll collect seeds and a cheaper way of growing flowering plants like marigolds and zinnias and dahlias. I've had success with that.
You've got to get to your question because we're running out of time.
Yeah, yeah. I saved zucchini and spaghetti squash seeds, and I got gourds. So it seems like gourds must be some wild type of squash, inedible, but beautiful.
Okay. Chris, what do you think of that?
I would be surprised if a gourd was apparent in there. I'm wondering if maybe you had an outcrossing event where somebody was growing gourds near you, the bees moved it over, and then when you save seeds, you had that gourd genetics in there.
Can any of them cross pollinate? And you get some weird answer at the end?
Oh, yeah. So within a species, they can cross pollinate. So a zucchini and a jack lanner can cross pollinate a gourd, can cross pollinate with them. Even across species, to some extent, they can do that, so.
If you really want to save your seed, you should, you really need to kind of keep the bees out and do the pollination yourself.
Well, I'll
That's the surest way to make sure you get what you're hoping for.
Keep the pollination yourself. A little paintbrush with the back and forth for the flowers?
Yeah, we actually, so we close the flower with a twist tie before they open. The day before they open, you can tell because they start to get a little yellow at the tips. And then we, the next in the morning, we take the male off the plant and we remove its flowers and we use it like a paintbrush, the male flower, on the female flower. And then we, then we close the female flower back up to keep the bees out.
Wow, that is fascinating. Dr. Hernandez, thank you for taking time to be with us today.
Yeah, thank you. It was great being on.
Dr. Chris Hernandez, Assistant Professor of Plant Breeding at the University of New Hampshire in Durham, and he's the Director of the university's Squash, Pumpkin, and Melon Breeding Program.
Today's episode was produced by Shoshana Buxbaum. I'm Flora Lichtman. Thanks for listening.
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