The Cannabis Breeder's Bible (38 page)

• nutrition

• soil condition

• water

We also know that evolution may have caused changes in the hereditary characteristics of groups of organisms over the course of generations. Along with this we have seen the consequences of chance, coincidence, and chaos with regard to wild cannabis plant populations. Wild cannabis does not overrun the planet because:

• many plants are killed by predators;

• some plants are faster and more vigorous than cannabis.

The reproductive potential of cannabis is massive but the wild cannabis populations tend to remain steady in size because:

• cannabis populations suffer from high mortality in the wild;

• Wild individuals usually have variations within populations and this leads to unstable survival rates for some individuals in that population.

This should give you a clearer understanding of why and how species evolve and also how domestication has influenced the evolution of the cannabis plant.

FILIAL GENERATIONS

In breeding we use the following symbols to denote certain circumstances surrounding an offspring’s appearance.

F = “filial.” It designates the offspring of a cross.

F1 = the offspring result of the mating of two parent plants. F1 seed gives rise to F1 plants. These produce F2 seed, which creates F2 plants. These produce F3 seed, which gives rise to F3 plants, and so on.

F2:3 = an F3 line that was derived from an F2 line by a process of selection.

F4:5 = an F5 derived line in the F4 by a process of selection.

Let’s recap what we’ve learned about inheritance and expand on it.

ADVANCED PRINCIPLES OF INHERITANCES

The chart below illustrates the Inheritance of two independent genes where YYBB = Large, Blue Bud and yybb = small, black bud.

The genotypes of F1 are all heterozygous -> YyBb. Phenotypes of F1 are all Large and Blue Bud.

The F2:

In the F2 the genotypic results and ratios are 9 Large, Blue buds (1 - YYBB, 2 - YYBb, 2 - YyBB, 4- YyBb) : 3 Large, Black buds (1 - YYbb, 2 - Yybb) : 3 small, blue buds (1 - yyBB, 2 - yyBb) : 1 small, black bud (1 - yybb).

Gene interaction can also control the same character. A gene that masks the effects of another is said to be “epistatic” to the gene. Here are some types of gene interaction.

Complementary Genes

This occurs when a dominant allele is present at two different loci. Both gene Y and gene B must be present for expression.

The underlined combinations in this Punnet square convey this while the remainder do not. This F2 phenotypic ratio is 9:7.

Additive Genes

This situation occurs when the concentration of a character is amplified by the interaction of two genes.

The 9 underlined combinations have expressed this completely. The 6 combinations in brackets have partial expression of the trait. The homozygous recessive with + and + in-between it does not. The F2 phenotype ratio is 9: 6: 1.

Duplicate Genes

This occurs when 2 genes have the same expression.

The F2 have the same phenotype, except for the homozygous recessive, which does not express the gene. The F2 phenotype ratio is 15:1.

Suppressor Genes

These occur when a dominant gene’s dominant expression is inhibited by another gene that is also dominant. For instance - Y dominates B.

12 underlined boxes show where Y is superior to B. In the homozygous recessive between the + + indicators, B is also not expressed. There are 3 genotypes that allow B to be expressed. The F2 phenotype ratio is 13:3.

Dominant Epistasis

This occurs when Y dominates B and B is only expressed when no dominant Y allele is present.

Gene Y is expressed 12 times; 3 times gene B is expressed. The homozygous recessive in between the ++ does not express the gene. The F2 phenotype ratio is 12:3:1.

Modifying Genes

This occurs if gene Y dominates gene B, yet gene B intensifies expression of Y. Gene B also has no expression of the trait on its own.

9 of the underlined indicators express an exaggerated outcome of gene Y; 3 of the genes marked inside the brackets allow Y to be expressed but not as exaggerated. In the 4 remaining indicators Y is not expressed. The F2 phenotype ratio is 9:3:1.

Linked Genes

These occur when two or more genes in adjacent proximity on a chromosome cause a combining genotype.

CUBING

Cubing is a type of selective breeding that has gained some popularity among breeders but has disadvantages in that it does not selectively stabilize traits or make a strain more uniform in growth.
¹⁴
Cubing involves a certain amount of random mating and is used mainly to create desirable females or mothers plants in populations that are too small to be adequate for proper selections. Smaller breeding outfits will probably use cubing to find sought-after mother plants.

In the F1 offspring all the pollen from the males are extracted and put into one container. All of the male pollen is then used in a backcross with the mother plant to produce the first backcross progeny. In the offspring you should find a good clone mother or in future offspring by repeating this methodology - cubing. The problem is that the male that contributes to this clone mother female is unknown and so the process can not be repeated. The procedure is as follows:

In the F1 select a female that is desirable and backcross this female with her farther to create the offspring. Collect all the pollen from the males in this offspring and use all of this pollen to pollinate the mother plant that contributed to this offspring. Grow out the offspring and keep repeating the process until a very desirable female is found.

Obviously cubing is not really breeding and anything that you hear about cubing being able to stabilize traits is false (it can happen that a trait is stabilized, or a number of traits are stabilized, through cubing, but this occurs by accident and is not selective breeding). Cubing is just a way to generate mother plants in small populations.

A myth has been going around that cubing can create male parents for popular clones that do not have a male version. This is false and is just a sales gimmick. Cubing does not create males from a popular clone nor can cubing be used to create a standard seed format strain that is somewhat like 75% to 90% of the popular clone. It simply doesn’t do that.

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CANNABIS PHOTOSYNTHESIS CHEMISTRY

TWO TYPES OF CHLOROPHYLL ARE FOUND in plants - chlorophyll ‘a’ and chlorophyll ‘b’.