Every fall, pumpkin growers carry their record-breaking giants on scales, with some pumpkins weighing more than 2,700 books (1,225 kilograms). Again the world’s largest apple weighs just 4 pounds (1.8 kg), and the Heaviest blueberry ever grown weighs less than an ounce (28 grams). So what allows pumpkins to grow to such staggering sizes while other fruits (yes, pumpkins are fruits and even a bay type) remain relatively small?
Giant pumpkins are a specific variety of The biggest pumpkin which has been bred to grow enormously – most commonly Mammoth and Atlantic Giant varieties. One of the basic reasons they can grow so large is that they are indeterminate plants, Vikram Baligaassistant professor of horticultural practice at Texas Tech University, told Live Science. While determinate plants grow to a set size and then stop, indeterminate plants grow indefinitely.
Determinate plants tend to produce all their fruits at once, which benefits for the harvest but limits their size.
“Some plants, when they grow an organ – whether it’s a leaf or a fruit or a flower – have a program that limits the size of that particular thing that they’re growing.” Jessica Sauvageassociate professor at the Swenson College of Science and Engineering at the University of Minnesota Duluth, told Live Science. “Other species don’t have this kind of limit. … For some reason, pumpkins don’t seem to have a very strong one that limits their size, which allows us to breed for larger ones.”
Without anything limiting their growth potential, pumpkin plants can continually add more leaves to generate energy for their fruit.
“With an indeterminate plant, its goal is to produce as much biomass as possible, as quickly as possible, so your pumpkin is going to bear leaves and stems and all sorts of things,” Baliga said. “Then if it needs to produce more energy, it just grows more leaves. It doesn’t have that genetic choke point.”
How to Grow a Giant Pumpkin
Growers take advantage of this by removing all but one pumpkin from the vine.
“If you have this plant that can store all these resources and you take eight pumpkins off the plant and leave one, you’re like, ‘Great, I’m just going to divert it all to this one fruit. This is my only chance to continue my business.’ genetic“, explained Baliga.
Technically, this trick also works with other fruits. Removing all but one peach from a tree, for example, can produce a larger peach. But this is where the laws of physics come into play.
On the one hand, pumpkins grow on the ground, so they are less subject to the attraction of gravity; a giant peach wouldn’t be able to grow to the size of a pumpkin because it would fall from the tree long before reaching that weight.
Additionally, a pumpkin’s hard rind allows it to grow larger than a soft-skinned fruit. “You wouldn’t be able to get a really big fruit out of something really soft, because it would start to weigh down and break apart,” Savage said.
However, too stiff a crust will not allow the pumpkin to reach massive size. “People who grow pumpkins work to get that sweet spot – you don’t want them to be so stiff that they can’t expand. … If the skin splits, it’s not competitive. So you have to have the skin soft enough, but it has to be strong enough to be able to support its own weight.”
When young, giant pumpkins have soft, thin skin that allows them to grow quickly. As they mature, the skin toughens, Savage said. Producers protect pumpkins from the sun by covering them with a tarpaulin to keep them in this gentle and rapid growth phase as long as possible.
At peak growth, giant pumpkins can gain 44 pounds (20 kg) per day — and all that mass has to move through the fruit’s vascular system, which Savage says is “overkill.” Savage and his team found that, compared to other pumpkin varieties, giant pumpkins have more phloemwhich is the part of the vascular system that transports sugar.
“I often think of it as a highway,” she said. “You can move the same amount on a small highway, but you’re limited by how quickly that happens. If you want to move a lot more resources faster…you have to have more roads.”
Giant pumpkins also have plenty of time to grow. “A pumpkin stays on the vine for months…it’s like a five to six month harvest, 180 days in some cases,” Baliga said. “Whereas your apples, your peaches, your pears and a lot of your blueberries tend to go from flower to harvest much more quickly.”
But an equally important reason why giant pumpkins get so big is because we made them that way. “They’ve been selectively bred for a very long time just for size, which is different from a lot of other foods where we also breed them for taste,” Savage said.
Pumpkins are a symbol of autumn and in the center of Halloween And Thanksgiving traditions, they therefore occupy a more important place in our culture than other fruits with similar growth potential, such as cucumbers.
For his part, Savage thinks the pumpkins will continue to get bigger. “There will probably be a limit, but I think we will continue to find ways to push it,” she said.
Fruits and Vegetables Quiz: Do you know where pumpkins, blueberries and broccoli come from?
