Why must plant breeders prevent unwanted pollen from reaching a selected female flower?

In plant breeding, it is imperative that only pollen from the desired male parent reaches the stigma of the female parent to ensure the genetic integrity of the resulting progeny.1

When breeders perform controlled hybridization, the objective is to combine specific, desirable genes from two selected parents to produce superior offspring. If "foreign" or unwanted pollen reaches the female flower, it can fertilize the ovules, leading to unintended genetic combinations that do not reflect the breeder's goals.21

To prevent this, breeders take several precautions:
* Removal of Anthers: In flowers containing both male and female parts, breeders remove the anthers from the selected female parent before they shed pollen to prevent self-pollination.1
* Physical Protection: Flowers are often covered with plastic or paper bags to shield the stigma from accidental exposure to wind-borne or insect-borne foreign pollen.1
* Controlled Application: Once the stigma is receptive, the breeder manually applies the specific, desired pollen and replaces the protective covering.1

These exacting, time-consuming measures ensure that the resulting seeds are true to the intended cross.1