Sweet corn history?

[Diane Whitehead]

A long time ago we were advised to have a pot of water already boiling when we went to pick some corn.

Now I can eat corn that I bought several days before, and it is delicious.

What was done to produce corn that keeps its sweetness?

[reed]

If I understand it correctly, when a corn kernel develops it is first filled with sugar that then converts to starch as the kernel matures. When an ear is removed from the stalk the conversion to starch starts immediately. Corn carrying a natural gene mutation called su, delays the starch conversion and makes it sweeter for longer. 

Then they discovered another gene called (se) that delays the conversion even longer. Then they started breeding both of those genes into the same line to make it stay sweet longer still and now they have things called SH2, synergistic and I'm not sure what else and who knows what else is new since I researched it several years ago. I never bothered to really understand what SH2 and synergistic means except that it inhibits the conversion so much that it can stay sweet much longer after harvest.

The failure of the sugar / starch conversion is what causes the kernels to be shrunken and wrinkled up when it dries. It also results in the corn sprout not having anything to eat before it develops a good root system which makes it more prone to disease and such as a seedling. To protect the starving sprout is why they almost always coat the seed in colorful poisons. 

I like the older (su) types best but (se) is good too. Even though it loses its sweetness faster after harvesting if you pick it just right and have the water boiling first it really is the best. That's fine for me because I regard sweet corn as a summertime treat, rather than a day-to-day food.

Folks that like corn outside of the local season or that they can keep in the fridge for a week need the newer types, but it is hard to grow and save seed from them in a backyard garden. The seeds are just weak and puny compared to the older types are hard to grow without the poison treatments and I don't want even a little bit of that in my garden.

[Carol Deppe]

I like the flavor of the old-fashioned su corns when picked optimally, but you usually have only about a three day window to pick them optimally. And it's hard to catch them within that window.

My favorite sweet corns are sugary enhanced. That is, they are su su se __. Homozygous for the sugary gene and homozygous or heterozygous for sugary enhancer. These are sweeter than su su corns, have a much longer picking window, and, and hold better off the plant. The flavor is a bit different from su su corns. Some have good cold-weather seed emergence. Hybrids are an advantage because the uniformity makes it easier to pick within the optimal picking window. I prefer the level of sweetness of the su su se se+ hybrids too. The supersweets are based on the shruken gene, which causes sugar levels so high they might as well be candy. They have a distinct flavor I consider foul. That is mostly what you find in grocery stores or even farmers markets these days. When I have accidently bought one I take one bite, then spit it out and throw the rest away. They have really long picking and holding windows.

Whether the flinty layer is white, yellow, or bicolor dramatically affects flavor. I like whites best. Bicolors are sweeter.

There are a number of open pollinated se as well as supersweets bred by OSSI-associated breeders. You can find them on the variety page on the website.

se corns may have good cold weather emergence. I find it best to presoak seed indoors to break dormancy and give them a headstart. Supersweet corns usually have poor cold weather emergence and are often started indoors and transplanted.

[Diane Whitehead]

I've just looked up corn in a local seed catalogue.

OP   Golden Bantam

Normal/Sugary (SU)  Golden Jubilee

Synergistic (SY)  Temptress

Sugary Enhanced (SE)  Peaches and Cream (this is the one I buy), Sugar Buns, Bodacious

Supersweet (SH2)  Equinox, Solstice

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and there are a few that are described as hybrids that are combinations of some of the above:  Honey Select, Enchanted, Jubilee Super Sweet

[Carol Deppe]

You can dehybridize Peaches and Cream or other en corns if you like.

They are all homozygous for su.
Most of them are heterozygous for en. You can identify the
en en kernels by picking the ears for seed saving a little before when the ears have dried down all the way. The homozygous en kernels dry down much slower than the rest. They will be big fat kernels which really stick out against the non-en wrinkled dried down kernels. Go over each ear and mark all the en en kernels with a line across the top with a black magic marker. Then put the ears somewhere they can finish drying down. Soon the ears will have all wrinkled kernels and only the marks you put on the en en kernels tells you which they are. So you can get the material homozygous for en in one seed saving event. If you separate white and yellow kernels the whites are already a pure breeding white en variety. The yellows will be a mix of homozygous and heterozygous yellow. Separate whites and yellows in sunlight while on the cob. Otherwise you can't always tell heterozygous yellows from whites. Of course, if you want a bicolor, you can just leave a mix of colors in the material. The blunt pointy end of a nail file is great for popping chosen dry kernels off of fully dried ears.

In choosing which en variety to dehybridize-- if you choose a late season corn with fat ears you may not be able to dry the ears down at all without putting them in a dehydrator. Early to mid season variety with ears no more than 2" thick across the base is what works best. To dry even non en corn down well enough to get kernels off in maritime NW I put shucked ears in wire baskets in front of a fan indoors. And turn baskets and rearrange ears daily at first. Or pile ears on tarp in front of fan and rearrange often at first.

If you want a bicolor remember that yellow is dominant. So if you want equal amounts of yellow and white kernels your planting seed needs to have more white than yellow.