Cultivation began with the Indians of middle America. Today's maize has been bred in the course of over 7000 years from a simple wild variety. The breeding of early ripening, cold tolerant hybrid varieties was a prerequisite for the expansion of maize cultivation to the temperate zones. For corn maize, the corn yield is critical but for silage the total dry mass and the ear fraction is important. By improving the protein composition, malnutrition in developing countries could be prevented.
Further aspects are stability, cold tolerance and maturation period.