Our Process
Yggdrasil is constantly working to add variety to our program of genetics while also refining the cultivars that have gained traction with our customers to improve consistency from seed to seed and bring out favorable characteristics.
We routinely carry F1 stock, BX1, S1, and F2’s. To help with clarification on the terminology of plant genetics, here is a breakdown as to what all the labels mean:
F1
An F1 plant refers to the first filial generation of offspring produced by crossing two distinct, genetically different parental lines, often referred to as P1 plants. In the context of plant breeding, including cannabis, an F1 generation results from a controlled cross-pollination between two different strains or varieties.
Hybrid Vigor
F1 hybrids may exhibit hybrid vigor, or heterosis, in which some traits exceed those of the parents. The effect depends on the parental lines and the trait being measured; it is not guaranteed.
Uniformity
An F1 cross is not automatically uniform. High uniformity is more reliably associated with crosses between genetically stable or inbred parental lines; genetically diverse parents can produce variable F1 offspring.
Stability
Uniform appearance does not mean an F1 population will breed true. Traits can segregate in later generations, depending on the genetic makeup of the parental lines.
F2
F2 refers to the second filial generation, produced by crossing F1 individuals from the same cross or by self-pollinating an F1 individual. Recombination and segregation can reveal variation, but its extent depends on the parental genetics and the traits involved.
Here are some key points about F2 plants:
Increased Genetic Variation
F2 plants can show a range of phenotypes as parental alleles segregate and recombine. The amount of variation depends on the genetic diversity of the original parents and the traits being observed; not every F2 population behaves alike.
Segregation of Traits
In the F2 generation, alleles can segregate into new combinations, allowing recessive traits hidden in heterozygous F1 individuals to become visible. Observed patterns depend on the genes involved and environmental influences.
Breeding Selection
F2 plants are often used by breeders to identify and select desirable traits. Breeders can choose individuals from the F2 population that express specific traits they want to stabilize in subsequent generations.
F2 populations can reveal variation that was less apparent in the F1 generation. The F2 label alone does not establish how variable or predictable a population will be.
BX1
BX1 stands for the first backcross generation: offspring of a hybrid crossed back to one of its original parents, known as the recurrent parent. A single backcross increases that parent’s expected genetic contribution but does not guarantee stable traits.
1) A breeder crosses two distinct parent plants (P1 and P2) to produce an F1 hybrid.
2) The F1 hybrid is then crossed back to one of its original parents (usually the parent with the desired traits), resulting in the BX1 generation.
Key characteristics of BX1 plants:
Trait Reinforcement
Backcrossing is used to increase the genetic contribution of a selected parent and improve the likelihood of recovering particular parental traits. However, BX1 offspring can still exhibit genetic variation, and a single backcross does not guarantee uniformity or trait stability.
Genetic Similarity
BX1 offspring have a greater expected genetic contribution from the recurrent parent than the initial hybrid does, while retaining genetic material from the other parent. Individual offspring can differ in the traits they express.
Further Backcrossing (BX2, BX3, etc.)
Further backcross generations are called BX2, BX3, and so on. Repeated backcrossing generally increases the recurrent parent’s expected genetic contribution, but does not by itself guarantee uniformity or trait stability.
Backcrossing changes the balance of parental genetic contributions. Repeated backcrossing can reduce genetic diversity; its effects depend on the parental lines and the genetic variation retained.
S1
S1 is the first selfed generation: offspring produced when a plant is fertilized by its own pollen. It describes the mating history, not a guarantee that the offspring will be uniform or identical to the parent.
Key Characteristics of S1 Plants:
Self-Pollination
Self-pollination brings together pollen and ovules from the same individual. Both genetic contributions come from that parent, but segregation and recombination can produce offspring that differ from one another.
Genetic Uniformity
Sharing one parent does not make S1 offspring genetically identical. A heterozygous parent can produce a range of allele combinations, so traits may vary within the first selfed generation.
Trait Stability
A single selfed generation does not automatically fix a parent’s traits. Whether a characteristic is retained depends on its genetic basis and the parent’s genotype.
Increased Homozygosity
Selfing increases homozygosity, meaning more gene loci carry matching alleles. This can expose recessive variation, including harmful alleles, without necessarily making the offspring uniform.
Feminized Seeds
In cannabis, selfed offspring of an XX parent are generally expected to be XX. S1 identifies the selfed generation, however, and does not by itself guarantee sex expression or the absence of intersex traits.
S1 offspring are not genetic copies of the original parent. Selfing can reduce heterozygosity and expose recessive alleles; whether this leads to inbreeding depression depends on the parent’s genetic makeup.