Corn hybrids are not forever

You might remember the James Bond movie “Diamonds are Forever.” Unfortunately, new corn hybrids only last a few years. After all that time searching for the needle in the haystack, there’s only a small window to use it.

Previously, I’ve discussed how corn breeders find the diamond, or needle in the haystack, after six to eight years of inbred development and testing.

Key Points

• Increasing parent lines is the first step in the process.

• Breeder’s seed is planted to create foundation seed.

• Flowering dynamics determine when each line is planted.

First steps

We increase seed of each parent line by hand pollination to produce “breeder’s seed.” We also plant a small plot of each inbred parent and examine every plant for purity, uniformity, disease resistance, plant and ear height, roots and stalks, and tassel type. Off-types and outcrosses are discarded.

Ears are hand-harvested, dried and taken to the lab. Ears are checked for disease, number of kernels per row, test weight, uniformity and purity. Selected ears are shelled, cleaned and bagged. That becomes “breeder’s seed.”

Breeder’s seed is planted in isolated fields. Seed that’s harvested is “foundation seed,” used to produce commercial hybrid seed.

Breeders must have flowering data on each parent line. They must decide if the line would be a good female or male parent. Female parents should have high yield potential, good seed quality and produce a high percentage of salable seed. Male parents should have good plant height and produce sufficient pollen for a long time.

Next steps

Using flowering data, the breeder determines the number of growing degree days required for silk emergence in the female line vs. pollen shed by the male. That’s called “nicking.” We need good synchronization of flowering. It’s rare that both parent lines flower at the same time. That’s why one parent is sometimes planted later. The goal is good pollination and seed set.

The male parent’s job is done after pollen shed, so those rows are cut down. Depending on the height and pollen production capacity of the male parent, the pattern and ratio of female-to-male parent rows varies. Seed fields are protected by spraying fungicides.

New beginning

Hybrid seed is harvested only from female rows and picked on the ear. Each ear is inspected. Off-types and diseased ears are discarded by sorting crews as ears make their way toward the dryers on conveyor belts.

Seed is dried to 12% moisture, shelled, graded, and treated with fungicides and insecticides. Then it’s bagged. Seed samples of each grade size are sent to the lab for germination and to winter locations where they are grown out to check for hybrid purity. Seed grades of the new hybrid that meet standards are finally available to you.

For the breeders, seeing their new hybrids planted on thousands of acres is very satisfying. The only thing more satisfying to me was holding my own babies when they were born.

Nanda writes from Indianapolis. He’s a crop consultant. Reach him at 317-501-9017 or

This article published in the April, 2010 edition of INDIANA PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.