Sugary, Sugar Enhanced and Supersweet Sweet Corn

I haven’t grown corn since the ’70’s. Back then there were white and yellow varieties of corn – that was it. I remember the excitement when the bicolor corn Butter and Sugar was first made available.

But if you look in a seed catalogue today, you’ll see that there are all kinds of different sweet corn. There’s sugary, sugar enhanced and supersweet and each of these types can be white, yellow or bicolor. Since I haven’t grown corn in a while, I hadn’t kept up with these changes. But when I started looking, I realized that there’s a whole new world of sweet corn out there for the gardener to try.

Bodacious Sweet Corn Rohrer Seeds Website

Bodacious Sweet Corn
Rohrer Seeds Website

All of these types have some kind of recessive gene that causes the endosperm of the kernel to have more sugar in it than you’d find in field corn. Sugary corn has the sugary gene (su-1) and these types are the standard varieties that have been grown for decades. The one problem with this type of corn is that once it’s harvested, the sugar in the endosperm is converted to starch very quickly. (The ear of corn that you buy is very much alive and this conversion of sugar to starch is part of its aging process.) That’s why fresh picked corn tastes so different from anything you’ll get in the store.

The sugar enhanced types are newer and have an additional gene, the sugar enhancer (se) gene. The endosperm of these kernels can have twice as much sugar in them as sugary varieties. While this sugar still converts to starch, there’s more sugar to begin with so the ears maintain their sweet taste for a longer time. Besides the sugar content, the pericarp (the outer part of the corn kernel) is much thinner in corn carrying the se gene.

Sugar enhanced corn comes in two distinct groups – homozygous and heterozygous. In homozygous sugar enhanced corn there are two paired se genes so 100% of the kernels on an ear have the enhanced sugar content. In heterozygous sugar enhanced corn, there’s  only one se gene so, following standard Mendelian genetics, 75% of the kernels are sugary and 25% are sugar enhanced.

The most recent type is the supersweet corn which carries the shrunken-2 (sh2) gene. This corn is even sweeter than the sugar enhanced type and the sugar in the endosperm isn’t converted readily into starch. The shelf life of this corn is much longer than other types. There are also some newer types (supersweet augmented and synergistic) where these three different genes are combined and stacked in various combinations to make even sweeter kernels.

I have seen that there’s some confusion out there about the se and sh2 genes. Some think that corn with these genes are genetically modified organisms (GMOs). The truth is that they are not GMOs. These genes are simply mutations that have been bred into these types of corn; they’re not genes that have been inserted through laboratory procedures. Besides, at this point in time, no GMO crops are available for sale to the home gardener.

The tassel of a corn plant is where the pollen is produced and it’s spread by the wind to the silks of the ear, each silk being a pistil that will produce a kernel. If you’re growing sweet corn and there’s any other kind of corn in the area that’s tasseling at the same time, you’re likely to get cross-pollination. The main sugary part of the corn kernel is the endosperm and two parts of this triploid tissue comes from the corn plant that the ear’s growing on and the other part comes from the pollen that lands on the silk (double fertilization).With all of these recessive sugar genes in play, the wrong kind of pollen can really mess up your corn.

This chart from the Ontario Ministry of Agriculture and Food shows what happens  when different types of pollen interact with different cob varieties.

Table 2. Isolation by Gene Type.

Pollen Type
Cob Type

Normal

Homozygous se

Heterozygous se

Super Sweet

Normal

OK (N)

N

N

F

Homozygous se

N

OK

OK

F

Heterozygous se

N

OK

OK

F

Super Sweet

F

F

F

OK

Indian

F

F

F

F

F = the cobs will develop field corn flavor and texture
N = the flavor will revert back to normal (su) sweet corn
OK = reaches the full sugar potential for that gene type

What this chart shows is that if you’re growing corn, the best thing to do is isolate each variety so that it self-pollinates and isn’t affected by the pollen of other corn varieties. You can achieve this isolation by allowing at least 250′ of space between different corn varieties. If you don’t have that much space, you can isolate varieties by making sure that there’s at least 14 days difference in the date of maturity of the corn that you’re growing. This will prevent having different kinds of corn tasseling at the same time.

While these newer types of corn have been around for a while, I have yet to see them offered at any local farmers’ markets. I’m going to ask a local market that I frequent why they don’t grow sugar enhanced or supersweet corn. I know they get their seeds from Harris Seeds and Harris offers all of these types of sweet corn. Maybe they can be the first market in the area to start offering these types of corn.

In the meantime I might have to grow my own to see if these new types of corn are worthy of all the hype. I am experimenting with growing some Bodacious corn (a homozygous sugar enhanced type) in a container – that’s a future post. Since I’m not sure I’ll get any corn from these container grown plants, maybe I’ll find some room in the garden to sow some Bodacious seeds. After learning about these corn types, I’d really like to taste them to see just how sweet they really are.

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4 responses to “Sugary, Sugar Enhanced and Supersweet Sweet Corn

  1. I don’t know what was available in seed catalogs in the 70s but a large number of corn varieties is certainly nothing new. You can look at catalogs from the 19th century and see quite a number of different breeds, including variations in color and kernal patterning we no longer see in commercial corn. (And I’m just talking about sweet corn, never mind flint and dent and whatnot.) Surely 70s catalogs at least had a handful of different yellow su-1 varieties.

    • I agree there have always been varieties but the sugar enhanced and supersweet varieties (and various combinations of these genes) are what’s new. That’s what I was focusing on in the article and those are new to the world of corn. That’s what I meant by all the different varieties that are available now that weren’t in the past.

  2. I sell sweet corn seed. Every year I grow a new variety sample that I get from Syngenta and Crookham. If you have’t tried honey select, do it! Its a triplesweet and by far my favorite so far. I am growing Cabo this season, which is a supersweet, should be ready in 2 weeks. Can’t wait! Around the Dakota’s many farm markets are now growing Serendipity, also a triplesweet, or trinity and ambrosia (both of these are SE) are the other 2 popular varieties for road side sellers. Our pricing and variety options can be found at http://www.edgewellag.com and we sell it by the pound and by bulk (25 LB & 50 LB Bags). I guarantee our prices beat Harris seeds hands down!

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