When the male and female germ cells join at fertilization, each adds one gene for each characteristic so that the new seed then has two genes for each attribute. The diverse combinations of each parents' genes determine the traits of the offspring and of future generations.
Inbreeding establishes a pure breed. A pure breed has consistent chromosomes. That is, the genetic makeup of offspring is relatively uniform. This true or pure breed is necessary so common growth characteristics may be established. If the plants are not a pure breed, it will be impossible to predict the outcome of the hybrid plant. After the 4th to 6th generation of inbreeding, negative characteristics, like low potency, legginess and lack of vigor tend to dominate. Inbreeding is necessary to establish a true breed, but has been shied away from after the strain has been established.
Inbreeding establishes a stable reference point or plant to start from. The chosen females are bred back (back crossed) with males of the same strain. This will establish a true breed, plants with the same growth characteristics. These plants, of known ancestry and growth characteristics will be used to breed hybrid plants.
Outbreeding or producing hybrid seed is the practice of crossing two plants from different genetic backgrounds. An F1 (make the 1 in F1 superscript) hybrid is a first generation cross of two true breeding plants. F1 varieties are the most sought after plants available because they grow approximately 25 percent faster and larger than other crosses. This phenomena is known as hybrid vigor.
The offspring of F1 plants are called F2 and the offspring of F2 plants are called F3 etc. The subsequent generations after F1 do not experience hybrid vigor. F1 hybrids from seed companies must be brought back to true bred plants before they serve as consistent breeding stock.
NOTE: Most often grower's do not breed, they cross plants without stabilizing any particular plant, or developing true breeding strains. Once they find a plant they like, they take clones of it and grow it out under lights. Often this is process is confused with breeding. It is much more difficult to select plants, stabilize them into true breeding plants and produce F1 (make the 1 in F1 superscript) hybrids. Often when 10 seeds purchased from a disreputable seed company are planted, the result is 10 plants that all look different, so beware!
Thanks! I needed that.
