Corn Breeding: Lessons From the Past
Corn Breeding: Lessons From the Past - Summary and Definitions of Key Words
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.
Zea mays L. – the scientific name of corn.
Race – a class of corn in which all plants of that class share certain characteristics, such as ear shape and number of kernel rows.
Open-pollinated variety – a variety of corn that is named for the manner in which seed of the variety is propagated across generations.
Self-pollination – the type of pollination that occurs when pollen from a single plant falls on the silks of that same plant.
Cross-pollination – the type of pollination that occurs when pollen from one plant falls on the silks of a different plant.
Inbreeding – a system of mating in which mates are more likely to be related than would occur if mating was random. Self-pollination is an extreme type of inbreeding.
Inbred – a pure-breeding strain of corn.
Single-cross hybrid – the type of hybrid that is produced when two different inbreds are cross-pollinated.
Hybrid vigor – the phenomenon of a hybrid plant having greater vigor than its parents.
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