How did early farmers improve crop plants before modern genetics was understood?

Before the formal understanding of genetics, early farmers improved crop plants primarily through artificial selection, a process that began at the dawn of agriculture.12

Early breeders practiced a form of "tentative selection" by observing the plants in their fields, identifying those with desirable traits—such as higher productivity or utility—and saving the seed from these superior specimens for the next planting season. Over thousands of years, this continuous, deliberate selection led to profound biological changes, effectively exploiting the natural pool of recessive mutations present in wild populations.132

Beyond simple selection, farmers also utilized:
* Vegetative propagation: For plants like tubers, farmers selected and replanted segments of stems or roots to maintain favorable characteristics.3
* Haphazard crossbreeding: Farmers often grew different varieties of the same crop in proximity, leading to natural, fortuitous crosses that sometimes resulted in more vigorous or productive offspring.4
* Conscious mixing: By the 19th century, some farmers began intentionally mixing different varieties to combine desirable qualities, a practice that preceded the scientific application of hybridization.4