Sweet corn is one of the most popular vegetables in the United States and Canada. Consumption is increasing in eastern Asia, Europe, and South America. In the U.S. it is a symbol of summer; consumers know the names of their favorite varieties, and each summer there are popular articles on the growing and preparation of sweet corn. When many Americans think of corn they think of sweet corn, seemingly not aware of the millions of acres of field corn that form the basis of American agriculture. Any corn consumed in the immature stage may be called sweet corn, but nearly all commercial sweet corn is based on one or more simple recessive alleles that alter the carbohydrate content of the endosperm.
Until 1961 the sugary1 (su1) allele on chromosome 4 defined sweet corn. In 1961, John Laughnan of the University of Illinois released the first supersweet variety.1 Currently, at least eight genes that affect carbohydrate synthesis in the endosperm are being used, either singly or in combination, in sweet corn varieties. Different endosperm types differ in eating quality, holding capacity (shelf life), and field emergence. They often require specialized seed production, planting techniques, and isolation from one another in the farmer’s field to prevent cross-pollination. The new endosperm types have complicated seed and crop production, but they have increased quality of both fresh and processed sweet corn. This has increased consumer satisfaction, which in turn has benefited the producer.
While the primary difference between field and sweet corn is altered carbohydrate composition in the endosperm, sweet corn is distinguished from other types of corn by many genes that affect all phases of plant growth. These genes affect table or eating quality (flavor, tenderness, and texture), appearance of ears and plants, and seed viability.
Sweet corn is not a race of maize or a separate subspecies within the species Zea mays (L.).2It is differentiated from other types of corn by a gene or genes that alter endosperm starch synthesis and its use as a vegetable. Differences between sweet corn and field corn and literature specific to sweet corn will be reviewed. However, much of the literature on field corn is applicable to sweet corn and should be examined for a complete view of the crop.