Why are F1 hybrid plants often more vigorous than either parent?

In plant breeding, the increased vigor observed in F1 hybrid plants compared to their parents is known as heterosis.1

This phenomenon occurs when two different pure-bred or inbred lines are crossed, resulting in first-generation offspring that exhibit superior characteristics—such as increased size, growth rate, fertility, and yield—beyond those of either parent.12

The process typically involves these key steps:
* Inbreeding: Breeders first develop highly uniform, pure-breeding inbred lines through several generations of self-pollination. During this phase, the vigor of the plants usually decreases significantly.2
* Crossing: When two unrelated inbred lines are crossed, this lost vigor is restored, often resulting in F1 hybrids that are much more productive than open-pollinated varieties.2

Because much of this hybrid vigor is lost in subsequent generations, farmers generally do not save seeds from hybrid crops. Instead, they purchase new, high-quality F1 hybrid seed each year to ensure consistent performance and maximum yield. This practice has been a transformative development in global agriculture, particularly in the production of corn.2