Most farmers do not choose to save seed because they can be assured that newly purchased seed is free of disease and pathogens, and in the case of hybrids, demonstrates hybrid vigor, with consistent, uniform characteristics.
“Seed saving” is not really an option with hybrid corn if a farmer wants consistency in his or her crops because saved the seed from hybrid crops (the offspring) does not “breed true” in successive generations, i.e., it does not deliver the quality and uniformity that farmers need. In soybeans, studies have shown that farmers get better yields when they buy new, “certified” seed rather than saved or “bin-run” seed. As Successful Farming magazine pointed out:
“Shawn Conley, a University of Wisconsin Extension agronomist, analyzed data that North Carolina State University researchers published in 1991 comparing bin-run to professionally grown seed. The researchers analyzed 204 comparisons across 6 years in 16 locations with 35 varieties. They found a 1.9 bushel per acre advantage to certified seed over bin-run seed. In some cases, they were higher. Conley notes Wisconsin data showed a 2.2 bushel per acre advantage for certified over bin-run seed. Today, this difference would likely be magnified due to improvements in seed technology, he adds.”
("Why it doesn't pay to plant bin-run soybean seed," Successful Farming, February 12, 2013)
Hybrids can be explained easily by revisiting high school Mendelian genetics 101:
When you cross two "true-breeding" parental varieties you create a hybrid. To be "true breeding,” the plants’ genes would have to be homozygous for whatever traits are desired. That means both alleles of a given gene would be either dominant (AA for example) or recessive (aa for example). For example, in looking at three genes, A, B and C, the genes in true breeding parent 1 could be AAbbCC and parent 2 could be aaBBcc. Each parent would be genetically different.
The hybrid offspring of these parents (crossing AAbbCC x aaBBcc) would be AaBbCc: one allele from each gene comes from parent 1 and the other allele from each gene comes from parent 2. The ears of corn (the offspring), which are genetically different from their parents, are harvested.
If you purchase new hybrid seed the next year that was produced again from the true breeding parents above, you will continue to produce corn plants that are genetically the same as the previous year’s crop (AbBbCc).
If on the other hand, you save the kernels from this offspring corn (AaBbCc) and plant them next year, the growing corn plants will fertilize themselves and each other. (Corn is wind-pollinated.)
The offspring of this cross (AaBbCc x AaBbCc) can produce a variety of 16 possible genetic combinations: AABBCC, AABBCc, AABbCC, AABbCc, AaBBCC, AaBBCc, AaBbCC, AaBbCc, AABBcc, AAbbCC, AAbbcc, aaBBCC, aabbCC, or aabbcc, half of which would not look like the parents.