The sh2 or Shrunken Gene Type:
1.The sh2 gene is called the shrunken gene because seeds appear shriveled due to less starch in the endosperm. That seeds weigh less than other genotypes should be considered when comparing seed costs and planting rates.
2.The sh2 types are often called the “super-sweets” because they are much sweeter than other genotypes. Some, but not many, sweet corn lovers have complained that sh2 types are too sweet.
3.Not only are the sh2 types much sweeter, but also they convert sugar to starch much more slowly than se or su types. This allows the grower a wider window for harvest and allows the end user to maintain quality sweet corn in a refrigerator longer.
4.The sh2 types have a crisper pericarp (kernel skin) than se or su types. Some people prefer the more tender se and su types, however, most find the crisp texture pleasing as long as it doesn’t get tough and chewy.
5.The main drawback of sh2 varieties has been their inability to withstand cold, wet conditions; hence, growers generally should plant the sh2 types later than other types and be prepared for emergency problems.
6.If sh2 types cross-pollinate with other corns, eating quality is lost. Blocks of sh2 planting should be isolated from other corns by at least a two track in the field. Better to plant sh2 types near varieties that do not pollinate within 10 days of the sh2. Best to separate sh2 types by pollination time and/or 250 feet.
The su or Normal Sugar Gene Type:
1.The better su types have excellent seedling vigor.
2.Because the conversion of sugar to starch is rapid after prime maturity, the window for harvest is narrow and storage time is limited.
3.Few su types are now favored over sh2 and se types in fresh market production.
The se or Sugary Enhancer Gene Type
1.The sugary enhancer gene is a modification of the normal sugary (su) gene. Though not as sweet as the sh2, the sweetness of se types is deliciously superior to su types. Plus the se kernels have a creamy endosperm like su types, unlike sh2 types.
2.Conversion of sugar to starch is slower in se types than in su types but not as slow as in sh2 types.
3.The tenderness of the se types is unsurpassed.
4.Isolation from other genotypes is not necessary but preferred.
5.Like all seed, seedling vigor of the se types can vary with variety and seed crop, however, as a class, se types generally germinate better and have more seedling vigor than sh2 types.
Sugar Levels of Sweet Corn Genotypes:
su Type – 5 to 12% sugar
se Type – 8 to 20% sugar
sh2 Type – 23-40% sugar
su Type: Silver Queen, Early Sunglow, Golden Cross Bantam, Honey & Cream.
se Type: Breeders Choice, Kandy Korn, Bodacious, Wardance.
sh2 Type: Early Extra Sweet, Illini Extra Sweet, Honey & Pearl.