Corn Breeding: Lessons From the Past - Summary

Although corn is grown across the world, it originated in the Americas. Types of corn are called races. Nearly all modern corn grown in the United States belongs to the Corn Belt Dent race, which largely was developed from two other races, the Northern Flints and the Southern Dents. 

Early American farmers developed and grew open-pollinated varieties, but from 1870 until 1930 the annual average corn grain yield in the United States did not increase. In the 1930s, open-pollinated varieties were gradually replaced by hybrids that were produced by crossing inbreds, and corn yields started to increase. Today, the average corn yield in the United States is approximately five times greater than it was 70 years ago. This increase is partly attributable to new breeding and testing methods that have resulted in genetically superior hybrids.