Improvement of Corn Germplasm

Corn is the most widely and intensively grown crop species in the world and ranks third in the world, behind rice and wheat, in total production. Corn originated in southern Mexico or northern Guatemala 5,000 to 10,000 years ago. Corn is extremely variable genetically, and selection pressures were effective in developing corn strains to meet the needs of the native inhabitants. Most of the genetic variability in corn was present before the European colonists arrived in the Western Hemisphere. Native Americans had developed races that were being grown in present-day southern Canada, the United States, Mexico, Central America, islands of the Caribbean, and throughout South America by 1492. Columbus collected corn on the northern coast of Cuba on his first trip. After corn was introduced in Spain in 1493, corn became distributed throughout the world, where it could be grown and cultivated within two generations (Manglesdorf, 1974). Corn breeding includes two separate, but equally important, components: 1) germplasm improvement and 2) development of inbred lines for use in hybrids. Genetic advance depends on the systematic improvement of germplasm, and all breeding programs should include both components