F1-hybrid seedlings are the result of crosses between two or more inbred lines. An inbred line is produced from a homozygous parent that has been self-pollinated a number of times to fix the genetic traits of the plant.

The result of crossing two selected inbred lines is an F1-hybrid that has superior traits for crop production.

Even though the F1-hybrid crop is heterogenous, it expresses uniform traits and has the added advantage of hybrid vigor.

Illustration of two inbred lines of corn, with pollination occurring between them.