Sweetness in corn results from a combination of genes. To keep it simple, we will not only use our layman’s definition of a gene, we will restrict the discussion to the three main genes that affect sweetness.
The Sugary Gene:
When a variety of sweet corn is thought of as having “normal” sweetness, it is a result of the Sugary gene, known to plant breeders as su-1. This gene increases the amount of sugar in the developing ear of corn. Varieties that are Sugary should be cooked and consumed quickly, as the sugar will convert to starch fairly rapidly following harvest.
The Sugary Enhanced Gene:
The Sugary Enhanced gene, known as the se gene, works together with the Sugary gene when both are involved in a variety. Sugary Enhanced varieties tend to be more tender and creamy. Such varieties have a higher maltose level as opposed to sucrose, which in part gives Sugary Enhanced varieties their unique flavor. Sugary Enhanced varieties will stay sweeter longer than Sugary varieties.
The Supersweet Gene:
Varieties with the Supersweet gene are known in plant breeding lingo also as shrunken-2 or sh2 varieties. This strange name is based on the fact that Supersweets have shrivelled seed kernels. When a variety is a Supersweet, it is very sweet, and the niblets are thought to be more crisp. Supersweet corn will retain its sweetness longer than both Sugary and Sugary Enhanced varieties.
The specialized genetic packages of sweet corn has implications for production. Varieties that are su-1, se and especially sh-2 must be “isolated” from all other varieties of any corn – sweet, silage or grain corn. This doesn’t mean one must grow shrunken-2 corn in Pemberton! If you cannot avoid planting two varieties of sweet corn in the same field, make sure you avoid planting one down-wind of another, and plant at least 100M away. Also, you can isolate in terms of time as well as distance. The pollination period is the key. If in doubt, ask your seed supplier, or a consulting agronomist for advice.