If you’re commercially growing sweet corn for market sale or processing, the last thing you want is an uneven or poor stand. One culprit is reduced-vigor seed, reports Gordon Johnson, University of Delaware Extension vegetable and fruit specialist.
Fields planted with seed lots with reduced-vigor seed often have healthy plants next to smaller, stunted plants. Those low-vigor plants can actually act as weeds, siphoning water and nutrients away from healthy plants and reducing their potential.
All in the genes — almost
By its nature, sweet corn has lower endosperm stored food reserves compared to field corn, explains the agronomist. But it has become more of an issue with homozygous sugary enhanced (se), shrunken supersweets (sh2), and the more recent augmented shrunken types.
In general, sweet corn vigor is rated, from highest to lowest, in this order: normal sugary (su) is higher than (sugar enhanced) heterozygous, which is higher than (se) homozygous, which is higher than shrunken sh2 augmented, which is higher than shrunken sh2. Synergistic (sy) sweet gene varieties may have seed with vigor characteristics of a se or a su sweet corn, depending on the specific genetics. Check with your sweet corn seed company for specifics.
Supersweet (shrunken sh2) hybrids inherently have low seed vigor. That’s why it’s highly recommended to plant them only when soil temperatures are above 60 degrees F. Vigor loss is magnified when a specific seed lot has problems.
Seed companies evaluate seed viability and vigor. But seed lots can decline between testing and sale. That’s why it’s advisable to retain seed lot samples for testing; then get it done as soon as possible if problems develop.
When trouble strikes
When you dig up the seed remnants and mesocotyls of stunted plants, kernels will be disintegrated and mesocotyls will be darkening. That means the seeds deteriorated prematurely, and the full content of the food reserves in the seed weren’t available for seedling development.
If a seed lot is suspected of having low vigor, a seed vigor test — not a germination test – is recommended. That’s doubly important for carryover seeds.
Source: Compiled from University of Delaware Crop Update