Corn Breeding: Mass Selection - Summary and Definitions of Key Terms

Mass selection occurs when the decision to select a plant is based on the performance of that plant. For centuries, farmers of various cultures have used mass selection to improve performance of many crops. However, mass selection for improved grain yield by American farmers in the 19th and early 20th centuries was largely ineffectual. Expected genetic gain from mass selection equals the product of narrow-sense heritability and the selection differential. However, this prediction equation does not account for negative impacts that can arise from inbreeding during selection. Ways to minimize inbreeding during selection were discussed.

Key Terms

Mass selection - a type of selection in which a plant is selected solely on the basis of the performance of that plant

Blocking - a technique of minimizing environmental variation in a field experiment by arranging plants into blocks and only directly comparing the performances of plants that are in the same block

Selection criterion - the trait or series of traits on which selection is based

Genetic gain - the difference in the mean value of the selection criterion between the original generation and the next generation, which is formed from the selected individuals, when these two groups are evaluated in the same environment

Breeders’ equation - a formula that predicts the genetic gain that will be realized from selection 

Selection differential - the difference between the mean performance of selected individuals and the mean performance of all individuals in the population, both unselected and selected

Population - a group of intermating individuals

Immigration - the introduction of new breeding members into a population

Closed population - a population without immigration

Inbreeding - the mating of related individuals