How does hybridization improve corn varieties?

Hybridization improves corn varieties primarily by exploiting hybrid vigour, also known as heterosis. This process results in significant agricultural advantages, including increased growth rates, greater uniformity, earlier flowering, and, most importantly, higher yields.12

The production of these varieties involves a systematic process:
* Inbreeding: Breeders perform selfing over several generations to create pure-breeding, uniform inbred lines. While this process reduces the plant's natural vigour, it ensures that the resulting hybrid remains consistent.1
* Crossing: When two unrelated inbred lines are crossed, the resulting F1 hybrid exhibits restored and often superior vigour compared to open-pollinated varieties.1
* Double Crosses: To reduce seed costs, breeders often use a double-cross method, where four inbred lines are crossed in pairs and then combined, allowing commercial seed to be produced on highly productive plants rather than low-yielding inbreds.1

Because much of this hybrid vigour is lost in subsequent generations, farmers must purchase new hybrid seed each year. This development has been one of the most impactful advancements in increasing global food supplies.1