Basic Breeding in the
Advanced Marijuana Cultivation forums; This info is from Greg Green's Cannabis Grow Bible via <a href="http://www.marijuanahydro.com" target="_blank">http://www.marijuanahydro.com </a>.
Your approach to breeding ...
This info is from Greg Green's Cannabis Grow Bible via <a href="http://www.marijuanahydro.com" target="_blank">http://www.marijuanahydro.com</a>.
Your approach to breeding will depend on what you ultimately hope to achieve. Do you want to create a new strain; create seeds that are similar to the parents; or cross two plants to create a simple hybrid strain?
Continuing a Strain through seeds
Say you purchased $120 worth of Silver Haze seeds and you want to make more seeds without any interference from another strain. That's easy. Just make sure that the male and female plants you breed with are from the same strain batch. In this instance the same strain batch would be Silver Haze from the same breeder. If you use Silver Haze from different breeders then the offspring may express a great deal of variation.This is because most breeders create their own versions of a popular strain. Their variety may have dissimilar characteristics from those of other breeders who have bred the same strain.
If you only have Silver Haze from the same breeder in your grow room, then all you need are a group of males and a group of females. Let the males pollinate the females and you will get more Silver Haze seeds, but you will loose some of the features of the original parent plants unless the strain you have is an IBL or from a very stable inbred pure line.
Making a Simple Hybrid
Again, making a simple hybrid is easy. Just take a male plant from one strain and a female plant from another, for example Big Bud and Skunk. The result will be vBig Bud x Skunk', but there will be differences in the offspring. Some of the plants will exhibit more Big Bud traits and some will exhibit more Skunk traits. Genes not expressed by each of the parents may also appear in the offspring.
If you want to breed for specific traits by eliminating variations, ultimately creating uniform plants or even an IBL, then you should start with a basic knowledge of plant genetics.
INTRODUCTION TO PLANT GENETICS
Genetics can be somewhat difficult to understand at first so we'll start by explaining a few rudimentary concepts and the basic terminology. The explanations for the words below can be treated as a glossary for your benefit.
Genes are the units of heredity transmitted from parent to offspring, usually as part of a chromosome. Genes usually control or determine a single characteristic in the offspring. There are genes responsible for each feature of your plant to be inherited, including leaf color, stem structure, texture, smell, potency, etc.
All of life is made up of a pattern of genes. You can think of this pattern as being similar to the two sides of a zipper. One side is inherited from the mother and the other from the father. Each gene occupies a specific locus, or particular space on the chain, and controls information about the eventual characteristics of the plant. So each gene locus contains two genes, one from the mother and one from the father. These gene pairs are usually denoted by a pair of letters, such as BB, Bb, Pp, pp, etc. Capital letters refer to dominant genes while lower case letters refer to recessive genes. By way of example, B can represent Big Bud while b can represent small bud. Any letter can be assigned to any trait or gene pair when you are working out your own breeding program.
A threadlike structure of nucleic acids and proteins in the cell nuclei of higher
organisms that carries a set of linked genes, usually paired.
A position on a chromosome where a particular gene pair is located.
Alleles are any of a number of alternative forms of one gene. For example the gene for purple bud color may have two forms, or alleles, one for purple and one for dark red.
Having identical alleles at one or more genetic loci, which is not a heterozygote (see below) and breeds true. Your plant is said to be homozygous for one feature when it carries the same gene twice in the responsible gene pair, which means both genes of the gene pair are identical.
Having different alleles at one or more genetic loci. Your plant is said to be heterozygous for one feature when the genes of the responsible gene pair are unequal, or dissimilar.
The phenotype is the summary of all of the features you can detect or recognize
on the outside of your plant, including color, smell and taste.
The genotype is the genetic constitution of your plant, as distinguished from the phenotype.The genotype characterizes how your plant looks from the inside. It is the summary of all the genetic information that your plant carries and passes on to its offspring.
Dominant is used to describe a gene or allele that is expressed even when inherited from only one parent. It is also used to describe a hereditary trait controlled by a gene and appearing in an individual to the exclusion of its counterpart, when alleles for both are present. Only one dominant allele in the gene pair must be present to become the expressed genotype and eventually the expressed pheno-type of your plant.
Recessive describes a gene, allele or hereditary trait perceptibly expressed only in homozygotes, being masked in heterozygotes by a dominant allele or trait. A gene is called recessive when its effect cannot be seen in the phenotype of your plant when only one allele is present.The same allele must be present twice in the gene pair in order for you to see it expressed in the phenotype of your plant.
Dominant/Recessive and Genetic Notation
Assume that the dominant'B'allele carries the hereditary trait for Big Bud, while the recessive xb' allele carries the hereditary trait for small bud. Since B is dominant, a plant with a Bb genotype will always produce Big Bud.The B is dominant over the b. In order for a recessive gene to be displayed in the phenotype, both genes in the gene pair must be recessive. So a plant with the BB or Bb gene will always produce Big Bud. Only a plant with the bb gene will produce small bud.
Now that we have explained the basic terminology of plant genetics, we can move on to the next step: rudimentary breeding concepts as laid out in the Hardy-Weinberg law of genetic equilibrium.
THE HARDY-WEINBERG MODEL OF GENETIC EQUILIBRIUM
An understanding of plant breeding requires a basic understanding of the Hardy-Weinberg law.To illustrate the value of the Hardy-Weinberg law, ask yourself a question, like: "If purple bud color is a dominant trait, why do some of the offspring of my purple bud strain have green buds?" or "I have been selecting Indica mothers and cross-breeding them with mostly Indica male plants but I have some Sativa leaves. Why?" These questions can be easily answered by developing an understanding of the Hardy-Weinberg law and the factors that can disrupt genetic equilibrium.
The first of these questions, reflects a very common misconception: that the dominant allele of a trait will always have the highest frequency in a population and the recessive allele will always have the lowest frequency.This is not always the case. A dominant trait will not necessarily spread to a whole population, nor will a recessive trait always eventually die out.
Gene frequencies can occur in high or low ratios, regardless of how the allele is expressed.The allele can also change, depending on certain conditions. It is these changes in gene frequencies over time that result in different plant characteristics.
A genetic population is basically a group of individuals of the same species (cannabis Indica or cannabis Sativa) or strain (Skunk#l or Master Kush) in a given area whose members can breed with one another.This means that they must share a common group of genes.This common group of genes is locally known as the gene pool.The gene pool contains the alleles for all of the traits in the entire population. For a step in evolution — a new plant species, strain or trait — to occur, some of the gene frequencies must change. The gene frequency of an allele refers to the number of times an allele for a particular trait occurs compared to the total number of alleles for that trait in the population. Gene frequency is calculated by dividing the number of a specific type of allele by the total number of alleles in the gene pool.
Genetic Equilibrium Theory and Application
The Hardy-Weinberg model of genetic equilibrium describes a theoretical situation in which there is no change in the gene pool. At equilibrium there can be no change or evolution.
Let's consider a population whose gene pool contains the alleles B and b.
Assign the letter p to the frequency of the dominant allele B and the letter q to the frequency of the recessive allele b. We know that the sum of all the alleles must equal 100 percent, so:
p + q = 100%
This can also be expressed as:
p + q = l
And all of the random possible combinations of the members of a population would equal:
p2 + 2pq + q2
p = frequency of the dominant allele in a population q = frequency of the recessive allele in a population p2 = percentage of homozygous dominant individuals q2 = percentage of heterozygous recessive individuals 2pq = percentage of heterozygous individuals
Imagine that you have grown a population of 1,000 'Black Domina' cannabis plants from seeds obtained from a well known seed bank. In that population, 360 plants emit a skunky smell, while the remaining 640 plants emit a fruity smell. You contact the seed bank and ask them which smell is dominant in this particular strain. Hypothetically, they tell you that the breeder selected for a fruity smell and the skunk smell is a recessive genotype. You can call this recessive genotype Vv'and use the formula above to answer the following questions.
QUESTION: According to the Hardy-Weinberg law, what is the frequency of the Vv'genotype?
ANSWER: Since 360 out of the 1,000 plants have the Vv'genotype, then 36% is the frequency of Vv' in this population of 'Black Domina'.
QUESTION: According to the Hardy-Weinberg law, what is the frequency of the Vallele?
ANSWER: The frequency of the Vv'allele is 36%. Since q2 is the percentage of homozygous recessive individuals, and q is the frequency of the recessive allele in a population, the following must also be true:
q2 = 0.36
(q x q) = 0.36
q = 0.6
Thus, the frequency of the Vallele is 60%.
QUESTION: According to the Hardy-Weinberg law, what is the frequency of the NV'allele?
ANSWER: Since q = 0.6, we can solve for p.
p + q = l
p + 0.6 = 1
p = 1 - 0.6
p = 0.4
The frequency of the VV allele is 40%.
QUESTION: According to the Hardy-Weinberg law, what is the frequency of the genotypesN W and 'Vv'?
ANSWER: Given what we know, the following must be true:
VV = p2
V = 0.4 = p
(p x p) = p2
(0.4 x0.4) = p2
0.16 = p2
VV = 0.16
The frequency of the genotype NVV is 16%
VV = 0.16
vv = 0.36
VV + Vv + vv = 1
0.16 + Vv + 0.36 = 1
0.52 + Vv = 1
Vv = 1 - 0.52
Vv = 0.48 or 48%
Or alternatively, NVv' is 2pq, therefore:
Vv = 2pq
2pq = 2 x p x q
2pq = 2 x 0.4 x 0.6
2pq = 0.48 or 48%
The frequencies of V and v (p and q) will remain unchanged, generation after generation, as long as the following five statements are true:
1. The population is large enough
2. There are no mutations
3. There are no preferences, for example a VV male does not prefer a vv female by its nature
4. No other outside population exchanges genes with this population
5. Natural selection does not favor any specific gene
The equation p2 + 2pq + q2 can be used to calculate the different frequencies. Although this equation is important to know about, we make use of other more basic calculations when breeding. The important thing to note here is the five conditions for equilibrium.
Earlier we asked the question: "I have been selecting Indica mothers and crossbreeding them with mostly Indica male plants but I have some Sativa leaves. Why?" The Hardy-Weinberg equilibrium tells us that outside genetics may have been introduced into the breeding program. Since the mostly Indica male plants are only mostly Indica and not pure Indica, you can expect to discover some Sativa characteristics in the offspring, including the Sativa leaf trait.
THE TEST CROSS
Some of you may be asking the question: "How do I know if a trait, such as bud color is homozygous dominant (BB), heterozygous (Bb) or homozygous recessive (bb)?"
If you've been given seeds or a clone you may have been told that a trait, such as potency, is homozygous dominant, heterozygous or homozygous recessive. However, you will want to establish this yourself, especially if you intend to use those specific traits in a future breeding plan. To do this, you will have to perform what is called a test cross.
Determining the phenotype of a plant is fairly straightforward. You look at the plant and you see, smell, feel or taste its phenotype. Determining the genotype cannot be achieved through simple observation alone.
Generally speaking, there are three possible genotypes for each plant trait. For example, if Golden Bud is dominant and Silver Bud is recessive, the possible genotypes are:
HOMOZYGOUS DOMINANT: HETEROZYGOUS: HOMOZYGOUS RECESSIVE:
BB = Golden Bud
Bb = Golden Bud
bb = Silver Bud
The Golden and Silver Bud colors are the phenotypes. BB, Bb and bb denote the genotypes. Because B is the dominant allele, Bb would appear Golden and not Silver. Most phenotypes are visual characteristics but some, like bud taste, are phenotypes that can't be observed by the naked eye and are experienced instead through the other senses.
For example, looking at a mostly Sativa species like a Skunk plant you will notice that the leaves are pale green. In a population of these Skunk plants you may notice that a few have dark green leaves. This suggests that this Skunk strain's leaf color is not true breeding, meaning that the leaf trait must be heterozygous because homozygous dominant and homozygous recessive traits are true breeding. Some of the Skunk's pale green leaf traits will probably be homozygous dominant in this population.
You may also be asking the question: "Could the pale green trait be the homozygous recessive trait and the dark green leaf the heterozygous trait?" Since a completely homozygous recessive population (bb) would not contain the allele ( for heterozygous expression (Bb) or for homozygous dominant expression (BB), it is impossible for the traits for heterozygous (Bb) or homozygous dominant (BB) to exist in a population that is completely homozygous recessive (bb) for that trait. If a population is completely homozygous for that trait (bb or BB), then that specific trait can be considered stable, true breeding or'will breed true'. If a population is heterozygous for that trait (Bb) then that specific trait can be considered unstable, not true breeding or 'will not breed true'.
If the trait for Bb or BB can not exist in a bb population for that trait, then bb is the only trait that you will discover in that population. Hence, bb is true breeding. If there is a variation in the trait, and the Hardy-Weinberg law of equilibrium has not been broken, the trait must be heterozygous. In our Skunk example there were only a few dark green leaves. This means that the dark green leaves are homozygous recessive and the pale green leaves are heterozygous and may possibly be homozygous dominant too.
You may also notice that the bud is golden on most of the plants. This also suggests that the Golden Bud color is a dominant trait. If buds on only a few of the plants are Silver, this suggests that the Silver trait is recessive. You know the only genotype that produces the recessive trait is homozygous recessive (bb). So if a plant displays a recessive trait in its phenotype, its genotype must be homozygous recessive. A plant that displays a recessive trait in its phenotype always has a homozygous recessive genotype. But this leaves you with an additional question to answer as well: are the Golden Bud or pale green leaf color traits homozygous dominant (BB) or heterozygous (Bb)? You cannot be completely certain of any of your inferences until you have completed a test cross.
A test cross is performed by breeding a plant with an unknown dominant genotype (BB or Bb) with a plant that is homozygous recessive (bb) for the same trait. For this test you will need another cannabis plant of the opposite sex that is homozygous recessive (bb) for the same trait.
This brings us to an important rule: If any offspring from a test cross display the recessive trait, the genotype of the parent with the dominant trait must be heterozygous and not homozygous.
In our example, our unknown genotype is either BB or Bb.The Silver Bud genotype is bb. We'll put this information into a mathematical series known as Punnett squares.
We start by entering the known genotypes. We do these calculations for two parents that will breed. We know that our recessive trait is bb and the other is either BB or Bb, so we'll use B? for the time being. Our next step is to fill the box in with what we can calculate.
The first row of offspring Bb and Bb will have the dominant trait of Golden Bud. The second row can either contain Bb or bb offspring.This will either lead to offspring that will produce more Golden Bud (Bb) or Silver Bud (bb).The first possible outcome (where ? = would give us Golden Bud (Bb) offspring.The second possible outcome (where ? = would give us Silver Bud (bb) offspring. We can also predict what the frequency will be.
Outcome 1, where ? = B:
Bb+ Bb+ Bb+ Bb = 4Bb
100% Golden Bud
Outcome 2, where ? = b:
Bb + Bb + bb + bb = 2bb
50% Golden Bud and 50% Silver Bud
Homozygous Dominant: Heterozygous: Homozygous Recessive:
BB = Golden Bud Bb = Golden Bud bb = Silver Bud
To determine the identity of B?, we used another cannabis plant of the opposite sex that was homozygous recessive (bb) for the same trait.
OUTCOME 2 TELLS US THAT:
• Both parents must have at least one b trait each to exhibit Silver Bud in the phenotype of the offspring.
• If any Silver Bud is produced in the offspring then the mystery parent (B?) must be heterozygous (Bb). It cannot be homozygous dominant (BB).
So, if a Golden Bud parent is crossed with a Silver Bud parent and produces only Golden Bud, then the Golden Bud parent must be homozygous dominant for that trait. If any Silver Bud offspring is produced, then the Golden Bud parent must be heterozygous for that trait.
To summarize, the guidelines for performing a test cross to determine the genotype of a plant exhibiting a dominant trait are:
1. The plant with the dominant trait should always be crossed with a plant with the recessive trait.
2. If any offspring display the recessive trait, the unknown genotype is heterozygous.
3. If all the offspring display the dominant trait, the unknown genotype is homozygous dominant.
The main reasoning behind performing a test cross are:
1. When you breed plants you want to continue a trait, like height, taste, smell, etc.
2. When you want to continue that trait you must know if it is homozygous dominant, heterozygous or homozygous recessive.
3. You can only determine this with certainty by performing a test cross.
We should mention that, as a breeder, you should be dealing with a large population in order to be certain of the results.The more plants you work with, the more reliable the results.
Hardy-Weinberg Law, Part 2
The question may arise: "How do I breed for several traits, like taste, smell, vigor and color?" To answer this question, you will need to learn more about the Hardy-Weinberg law of genetic equilibrium.
If you breed two plants that are heterozygous (Bb) for a trait, what will the offspring look like? The Punnett squares can help us determine the phenotypes, genotypes and gene frequencies of the offspring.
IN THIS GROUP,THE RESULTING OFFSPRING WILL BE:
1 BB - 25% of the offspring will be homozygous for the dominant allele (BB)
2 Bb - 50% will be heterozygous, like their parents (Bb) 1 bb - 25% will be homozygous for the recessive allele (bb)
Unlike their parents (Bb and Bb), 25 percent of offspring will express the recessive phenotype bb. So two parents that display Golden Bud but are both heterozygous (Bb) for that trait will produce offspring that exhibit the recessive Silver Bud trait, despite the fact that neither of the parents displays the phenotype for Silver Bud.
Understanding how recessive and dominant traits are passed down through the phenotype and genotype so that you can predict the outcome of a cross and lock down traits in future generations is really what breeding is all about.
When you breed a strain, how do you know that the traits you want to keep will actually be retained in the breeding process? This is where the test cross comes in. If you create seeds from a strain that you bought from a seed bank, how can you be sure that the offspring will exhibit the characteristics that you like? If the trait you wish to continue is homozygous dominant (BB) in both parent plants then there's no way that you can produce a recessive genotype for that trait in the offspring, as illustrated in the Punnett square below.
In order to breed a trait properly you must know if it is homozygous, heterozygous or homozygous recessive so that you can predict the results before they happen.
Mendel and the Pea Experiments
Gregor Mendel (1822-1884) was an Austrian monk who discovered the basic rules of inheritance by analyzing the results from his plant breeding research programs. He noticed that two types of pea plants gave very uniform results when bred within their own gene pools and not with one another.
He noticed that the offspring all carried the same traits when they bred with the same population or gene pool. Since there were no variations within each strain he guessed that both strains were homozygous for these traits. Because the pea plants were from the same species, Mendel guessed that either the solid seed shells were recessive or the wrinkled seed shells were recessive. Using the genotype notations SS for solid seed shells and ss for wrinkled seed shells, he knew that they couldn't be Ss because one lot didn't exhibit any of the other strain's phenotypes when bred within its own gene pool.
Let's illustrate this using two basic Punnett squares where SS is pea plant #1 with the trait for solid seed shells and ss is pea plant #2 with the trait for wrinkled seed shells.
Up until this point, he didn't know which trait was recessive and which was dominant. Since all the seeds shells were solid, he now know with certainty that pea plant #1 contained the dominant genotype for solid seed shells and pea plant #2 contained the recessive genotype for wrinkled seed shells. This meant that in future test crosses with other pea strains, he could determine if a particular seed shell trait was homozygous or heterozygous because he had identified the recessive trait (ss).
The Second Hybrid Cross (the F2 Generation)
The offspring in the Fl cross were all Ss. When Mendel crossed these offspring
he got the following results:
*Take special note of this offspring and compare with parents.
Mendel had mated two pea plants that were heterozygous (e.g., Ss) for a seed shell trait. In this group, the resulting offspring were:
25% of the offspring were homozygous for the dominant allele (SS) 50% were heterozygous, like their parents (Ss) 25% were homozygous for the recessive allele (ss)
In his first cross to create the hybrid plant, Mendel ended up with no recessive traits for seed shape. But when he crossed the offspring, because they were heterozygous for that trait, he ended up with some having the homozygous recessive trait, some having the homozygous dominant trait and some continuing the heterozygous trait. In correct breeding terms his first cross between the plants is called the Fl cross or Fl generation.The breeding out of those offspring is called the F2 cross or F2 generation.
Now since he has Ss, ss and SS to work with you could use Punnett squares to determine what the next generations of offspring will look like. Compare your results with what you have learned about ratios and you'll be able to see how it all fits together.
More on Genetic Frequencies
Take a look at the cross below between two heterozygous parents. If two heterozygous parents are crossed, the frequency ratio of the alleles will be 50% each. Remember the genotype can be Ss; SS or ss, but the allele is either VS' or Y.
We can see S S S S (4 x S) and s s s s (4 x s). This means that the frequency of the allele 'S' is 50% and the frequency of the allele V is 50%. See if you can calculate the frequencies of the alleles *S'and Y in the following crosses for yourself.
Recall that the Hardy-Weinberg law states that the sum of all the alleles in a population should equal 100 percent, but the individual alleles may appear in different ratios. There are five situations that can cause the law of equilibrium to fail. These are discussed next
1. MUTATION. A mutation is a change in genetic material, which can give rise to heritable variations in the offspring. Exposure to radiation can cause genetic mutation, for example. In this case the result would be a mutation of the plant's genetic code that would be transferred to its offspring. The effect is equivalent to a migration of foreign genetic material being introduced into the population. There are other factors that can cause mutations. Essentially a mutation is the result of DNA repair failure at the cellular level. Anything that causes DNA repair to fail can result in a mutation.
2. GENE MIGRATION. Over time, a population will reach equilibrium that will be maintained as long as no other genetic material migrates into the population. When new genetic material is introduced from another population, this is called introgression. During the process of introgression many new traits can arise in the original population, resulting in a shift in equilibrium.
3. GENETIC DRIFT. If a population is small, equilibrium is more easily violated, because a slight change in the number of alleles results in a significant change in genetic frequency. Even by chance alone certain traits can be eliminated from the population and the frequency of alleles can drift toward higher or lower values. Genetic drift is actually an evolutionary force that alters a population and demonstrates that the Hardy-Weinberg law of equilibrium cannot hold true over an indefinite period of time.
4. NON-RANDOM MATING. External or internal factors may influence a population to a point at which mating is no longer random. For example, if some female flowers develop earlier than others they will be able to gather pollen earlier than the rest. If some of the males release pollen early and then stop producing pollen, the mating between these early males and females is not random, and could result in late-flowering females ending up as a sinsemilla crop. This means that these late-flowering females won't be able to make their contribution to the gene pool in future generations. Equilibrium will not be maintained.
5. NATURAL SELECTION. With regards to natural selection, the environment and other factors can cause certain plants to produce a greater or smaller number of offspring. Some plants may have traits that make them less immune to disease, for example, meaning that when the population is exposed to disease, less of their offspring will survive to pass on genetic material, while others may produce more seeds or exhibit a greater degree of immunity, resulting in a greater number of offspring surviving to contribute genetic material to the population.
HOW TO TRUE BREED A STRAIN
Breeding and growing cannabis (growing marijuana) strains is all about manipulating gene frequencies. Most strains sold by reputable breeders through seed banks are very uniform in growth. This means that the breeder has attempted to lock certain genes down so that the genotypes of those traits are homozygous.
Imagine that a breeder has two strains: Master Kush and Silver Haze. The breeder lists a few traits that they particularly like (denoted by *).
This means they want to create a plant that is homozygous for the following traits and call it something like Silver Kush.
Pale green leaf Hashy smell Silver flowers Short plants
All the genetics needed are contained in the gene pools for Master Kush and Silver Haze.The breeder could simply mix both populations and hope for the best or try to save time, space and money by calculating the genotype for each trait and using the results to create an IBL.
The first thing the breeder must do is to understand the genotype of each trait that will be featured in ideal "Silver Kush" strain. In order to do this the genotype of each parent strain for that same trait must be understood. Since there are four traits that the breeder is trying to isolate, and 4x2 = 8, eight alleles make up the genotypes for these phenotype expressions and must be made known to the breeder.
Let's take the pale green leaf of the Silver Haze for starters. The breeder will grow out as many Silver Haze plants as possible, noting if any plants in the population display other leaf colors. If they do not, the breeder can assume that the trait is either homozygous dominant (SS) or recessive (ss). If other leaf colors appear within the population, the breeder must assume that the trait is heterozygous (Ss) and must be locked down through selective breeding. Let's look closely at the parents for a moment.
If both parents were SS there wouldn't be any variation in the population for this trait. It would already be locked-down and would always breed true without any variations.
With one SS parent and one Ss parent, the breeder would produce a 50:50 population — one group being homozygous (SS) and the other heterozygous (Ss).
If both parents were Ss, the breeder would have 25 percent SS, 50 percent Ss and 25 percent ss. Even though gene frequencies can be predicted, the breeder will not know with certainty whether the pale green leaf trait is dominant or recessive until they perform a test cross. By running several test crosses the breeder can isolate the plant that is either SS or ss and eliminate any Ss from the group. Once the genotype has been isolated and the population reduced to contain only plants with the same genotype, the breeding program can begin in earnest. Remember that the success of any cannabis growing and breeding program hinges on the breeder maintaining accurate records about parent plants and their descendants so that they can control gene frequencies.
Let's say that you run a seed bank company called PALE GREEN LEAF ONLY BUT EVERYTHING ELSE IS NOT UNIFORM LTD. The seeds that you create will all breed pale green leaves and the customer will be happy. In reality, customers want the exact same plant that won the cannabis cup last year or at least something very close. So in reality, you will have to isolate all the ^winning' traits before customers will be satisfied with what they're buying.
The number of tests it takes to know any given genotype isn't certain. You may have to use a wide selection of plants to achieve the goal, but nevertheless it is still achievable. The next step in a breeding program is to lock down other traits in that same population. Here is the hard part.
When you are working on locking down a trait you must not eliminate other desirable traits from the population. It is also possible to accidentally lock down an unwanted trait or eliminate desired traits if you are not careful. If this happens then you'll have to work harder to explore genotypes through multiple cross tests and lock down the desired traits. Eventually, through careful selection and record keeping you'll end up with a plant that breeds true for all of the features that you want. In essence, you will have your own genetic map of your cannabis plants.
Successful breeders don't try to map everything at once. Instead, they concentrate on the main phenotypes that will make their plant unique and of a high quality. Once they have locked down four or five traits they can move on. True breeding strains are created slowly, in stages. Well known true breeding strains like Skunk#l and Afghani#l took as long as 20 years to develop. If anyone states that they developed a true breeding strain in one or two years you can be sure that the genetics they started with were true breeding, homozygous, in the first place.
Eventually you will have your Silver Kush strain but only with the four genotypes that you wanted to keep. You may still have a variety of non-uniform plants in the group. Some may have purple stems, while others may have green stems. Some may be very potent and others not so potent. By constantly selecting for desired traits you could theoretically manipulate the strain into a true breeding strain for every phenotype. However, it is extremely unlikely that anyone will ever create a 100 percent true breeding strain for every single phenotype. Such a strain would be called a perfect IBL. If you're able to lock down 90 percent of the plant's phenotypes in a population then you can claim that your plant is an IBL.
The core idea behind the true breeding technique is to find what is known as a donor plant. A donor plant is one that contains a true breeding trait (homozygous, preferably dominant for that trait). The more locked down traits are homozygous dominant the better your chances of developing an IBL, which does not mean that the line of genetics will be true breeding for every trait, but rather that the strain is very uniform in growth for a high percentage of phenotypes.
Some additional advanced marijuana growing and breeding techniques that will help you to reduce or promote a trait in a population are discussed below. Using these techniques may not create a plant that is true breeding for the selected traits, but will certainly help to make the population more uniform for that trait.
ADVANCED BREEDING TECHNIQUES
Our first cross between the Master Kush plant and the Silver Haze is known as the Fl hybrid cross. Let's pretend that both traits are homozygous for leaf color: the Silver Haze is pale green and the Master Kush is dark green. Which is SS or ss? We won't know until we see the offspring.
Fl Hybrid Cross s
This Fl cross will result in hybrid seeds. Since S is dominant over s, we'll know which color is more dominant and from which parent it came from. In this example, the overall results are pale green.Thus, the pale green allele is dominant over the dark green.
S = Silver Haze pale green leaf trait is dominant s = Master Kush dark green leaf trait is recessive
We also know that because no variations occurred in the population that both parents were homozygous for that trait. However, all the offspring are heterozygous. Here is where we can take a shortcut in manipulating the gene pool for that population. By cloning the parent plant SS, we can use this clone in our cross with the Ss offspring. This is known as a backcross. Obviously, if our parent is female then we'll have to use males from the Ss selection in our backcross, and vice versa.
Now our first backcross will result in 50 percent homozygous (SS) offspring and 50 percent heterozygous offspring (Ss) for that trait. Here all the offspring will exhibit the pale green leaf trait. If we didn't backcross but just used the heterozygous offspring for the breeding program we would have ended up with 25
percent homozygous dominant (SS), 50 percent heterozygous (Ss) and 25 percent homozygous recessive (ss), as shown below.
Cross (without backcrossing)
S s S SS Ss s Ss ss
Backcrossing seriously helps to control the frequencies of a specific trait in the offspring. The F2 Hybrid Cross produced some plants with the dark green leaf trait. The F2 Backcross did not.
The F2 backcross is an example of simple backcrossing. Let's see what happens when we do our second backcross (F3) using the same original parent kept alive through cloning. Our second backcross is referred to as squaring. Since we're dealing with only two types of offspring Ss and SS, we'll either repeat the results of the F2 backcross...
F3 Backcross with heterozygote
In the F3 Backcross with the homozygote, all of the offspring are homozygous dominant (SS) and thus true breeding for that trait.These offspring are the result of squaring and can never produce the ss traits because the SS trait is now true breeding and stable. The F3 Backcross with the heterozygote has some Ss offspring. If we breed the Ss and Ss offspring we can produce the ss trait. This line would not be stable.
How to Generate a Clone Mother
The best way to generate a clone mother is to grow a large population of plants from the same strain. If the strain is an IBL then you should find that the plants do not exhibit much variation. It can be difficult to find a clone mother from an IBL strain, though, because IBLs are created to provide a population of plants from seed from the F3 Backcross with the homozygote, which all resemble the clone mother that the breeder enjoyed and wanted to share with you.
The best way to generate a clone mother is to select her from a large population of Fl hybrids. If you do not find a clone mother in the Fl population then allow random mating to occur and see if you can generate a good clone mother in the F2 population. If you do not find the clone mother in the F2 population then either grow a larger population or select different parents to create a new Fl population.
A clone mother is only as good as the environment she is grown in. The environment influences how the genotype is displayed in the phenotype.* Although indoor plants can grow outdoors and outdoor plants can grow indoors, the expressed phenotype of the genotype may change because of the diversity in growing conditions. This is why breeders urge that you grow their strains in the recommended environment.
Selfing is the ability of a plant to produce seeds without the aid of another plant and refers to hermaphrodite plants that are able to self-pollinate. Hermaphrodite plants have both male and female flowers.This usually means that the hermaphrodite plant is monoecious. Most plants are dioecious and have male and female flowers on separate plants.
Monoecious cannabis strains will always display both sexes regardless of the growing conditions. Under optimal growing conditions a monoecious cannabis strain will still produce both male and female flowers on the same plant. Under optimal growing conditions a dioecious cannabis strain will produce male and female flowers on separate plants.
Stressful growing conditions can cause some dioecious cannabis strains to produce both male and female flowers on the same plant. Manipulating an irregular photoperiod during the flowering stage is an easy way to encourage the dioecious hermaphrodite condition. Not all dioecious cannabis strains can become hermaphrodites. The dioecious cannabis strain must have a preexisting genetic disposition to become hermaphrodite under stressful conditions in order for male and female flowers to appear on the same plant.
If you find a dioecious cannabis strain that has the hermaphrodite condition you can separate this plant from the rest and allow selfing to occur. If the male pollen is viable on this plant then the hermaphrodite will produce seeds. Selfed plants that produce seeds will eventually generate offspring that:
1. Are all female
2. Are all hermaphrodite
3. Produce male, female and hermaphrodite plants because the environment also influences the final sexual expression of the selfed plant
4. Express limited variation from the original selfed plant
Breeders should note that it is nearly impossible for a hermaphrodite to create male plants although the environment can influence males to appear. Hermaphrodites usually create female-only and hermaphrodite seeds. The female-only seeds often carry the hermaphrodite trait. Selfing has become popular among those who wish to breed all-female or feminized seeds. Unfortunately feminized seeds do very little for the cannabis gene pool as the hermaphrodite condition prevents growers from generating a sinsemilla crop.
Well-informed breeders tend to shy away from producing feminized seeds. Feminized seeds should only be used for bud production and not for breeding. Generating seeds from feminized plants is only advised for personal use and not for distribution.
Notes on Selfing by Vie High
These notes were taken from an online interview. Notes provided by Vie High, BCGA breeder.
100% Female seeds
POSTED BYTHESILICONMAGICIAN ON FEBRUARY 13, 1999 AT 05:17:41 PT As some of you may know I've been a regular in the chat room for a while and I spend a large amount of time in there. I have had the extreme pleasure of speaking to Mr. XX over the last few nights for many hours and have gotten to know him quite well via email and the chat. He has confided in me and in a few others about his process for coming up with 100 percent female seeds.
Mr. XX is a very nice guy, funny too and it's always a pleasure to speak with him. He doesn't speak English too well, but his wit comes through the rough language and he's a riot. He's a pure lover of cannabis and feels that everyone should share and share alike. He simply wants to share his knowledge with the cannabis community, and because he's spent 15 years researching this, I spoke about it with him in depth.
He has stressed literally hundreds of plants with irregular photoperiods. What he does is put the lights on 12/12 for 10 days. Then he turns the lights on 24 hours, then 12/12 again for a few days, then back to 24 hours for a day, then 12/12 again for a few weeks. If he does this and no hermaphrodites come up, he has found a 100% XX female that can't turn hermaphrodite naturally. He claims that your chances of finding a 100% XX female is vastly increased when using Indica genetics. He also informed me that the more Afghani or Nepalese genetics the plant has, the better the chances of finding a natural XX female. In his own words: "Where did nature give weed a home originally?" I tried to get him to narrow it down to a ratio, but he never specified just how many plants per are XX females. He claims there are plenty of XX females for everybody, and that's all he will say on the subject. It takes a lot of time and a lot of plants to find that one female.
He then uses gibberellic acid, mixing 30 centiliters of water with 0.02 grams of gibberellic acid and 2 drops of natruim hydroxide to liquefy the gibberellic. Then applies as normal and creates the male flowers. He has gotten down to the 4th generation without loss of vigor, and with no genetic deficiencies and hermaphrodites. He claims that the plants are exact genetic clones of one another, complete sisters. Basically it's cloned from seed instead of from normal cloning methods.
POSTED BY THESILICON MAGICIAN ON FEBRUARY 13, 1999 AT 05:17:41 PT
Mr. XX also says that it's easy for the home grower to find an XX female. It's a very time-consuming process but a straightforward one. He advises home growers to confine themselves to a single strain. Mr. XX used a Skunktfl x Haze x Hawaiian Indica. He says to separate those plants from your main grow and stress them severely. Do this repeatedly with every new crop of seeds you get of that strain until you find the XX female. While this is time consuming it is by no means impossible.
What is an F1, F2, and IBL?
An IBL (inbred line) is a genetically homogeneous strain that grows uniformly from seed.
A hybrid is a strain made up of two genetically unlike parents, IBL or hybrid.
When you cross two different IBL strains for the FIRST time, it is called the F1 generation. When you cross two of the same F1 hybrid (inbreed), it is called the F2 generation.
The process of selective inbreeding must continue at least until the F4 to stabilize the recurrently selected traits. When you cross two specimens of an IBL variety, you get more of the same, because an IBL is homozygous, or true breeding for particular traits.
What should I look for in an IBL?
First define your goals. Are you growing for yourself or for commercial production? Indoors or out? Mostly sativa or mostly indica? Keep only the plants that have the qualities you want, and mercilessly kill the rest.
Select plants that don't fall over; if you have to prop them up with toothpicks, you might as well cull them. Keep the ones that are free from abnormalities and hermaphroditism. Hopefully you've got enough many seeds to be ruthless. Keep the ones that show better resistance to disease and pests. Even though the progeny performance is more important than the individual, there is a positive relationship between the overall vigour of an IBL and the yield of its hybrids. If they produce vigourous plants they are more likely to pass these traits on. Then employ a breeding strategy towards homozygosity, such as recurrent selection, selfing or cubing.
How do I select a male?
The only way to determine the value of a plant for breeding is to grow and examine its progeny. The most potent plant might not pass on this trait, and the healthiest plant might not have favorable combining ability. Judging a male by visual appearance and also smoke testing, or using bio-assay, should not be discounted, but test crossing the male is the only way to determine it's breeding potential.
See also Soul's Selecting Breeding Individuals...
Breeding for Beginers. Create Your very own strain!
This Text is not by any means the only breeding path which could be taken but is a good start for the lay persons wishing to have a little play being god/and see if they would like to play mother nature with their Garden.
A person must learn to be a good grower before they can become a good breeder.
Step One: Choose a male plant with desirable characteristics. One good way to choose male plants is to rub the stem with your finger. If the plant smells of resin and is pungent it could be a good plant.
Step Two: One branch of male flowers will supply all the pollen necessary. Strip away the other branches to guard against accidental, random pollination. Isolate the male from females once flowers start to show. Soon pollen sacks will begin to open.
Step Three: When the pollen pods open, place a clean, paper bag over the branch to collect pollen. Secure the bag at the bottom with a piece of string or a wire tie. Keep the bag over the branch for several days to collect pollen.
Step Four: When enough pollen has been collected, shake remaining pollen off into the bag. Remove spent branch and bag. This pollen can be "Dried" and saved in the freezer for several months. Moisture and high temperatures degrade and destroy pollen.
Step five: Ideally, fuzzy white pistils should be ready for fertilization 3 to 4 weeks after the first pistils appear. Cover the selected female branch with the pollen filled bag. Shake the bag.
NOTE: An alternate method is to use a small paint brush to apply pollen from the bag to the pistils if you want only a few seeds.
Step Seven: Leave the bag for two or three days, to ensure fertilization. Be careful not to scatter pollen on adjacent sinsemilla crop when removing the bag.
Step Eight: After fertilization, seeds will be ripe in 3-6 weeks. seeds when they split open the containing calyx or rattle in the pod.
seeds are ready to plant immediately, but all may not germinate. Germination percentage increases when seeds are stored in a cool dry place for one or two months.
Many variations of this could be done and like i said i want the lay person to be able to read a basic step by step intro guide so.
Growers can use simple crossing techniques to learn about breeding and work with traits that are fairly easy to change – such as, plant size, fragrance and potency. Even though simple experimentation, it is possible to produce the desirable plants.
To breed a grower must understand the principles of plant reproduction, heredity and environmental stress. By mastering these principles and simple techniques a grower can make crosses to produce new varieties or strains.
Cannabis plants inherit their genetic characteristics from their sets of parents. Natural heredity laws define why offspring inherit different traits from the same parents. These laws assist breeders to forecast the number of offspring that stand to inherit a specific trait. Anybody who is serious about breeding has a good background in the laws of heredity. It’s essential.
All plant cells contains chromosomes, microscopic forms inside cells. Genes occur in pairs within these chromosomes. Chromosomes are building blocks of genes and genes determine the characteristics of cannabis. Every cannabis cell contains two genes (one chromosome) for each characteristic. To illustrate, lets look at sex. Each plant has one male gene and one female gene. Cannabis has 10 pairs of chromosomes which makes a total of 20 chromosomes.
Diploid plants have the normal set of chromosomes that occur in pairs within the cells.
Polyploid plants have multiple sets of chromosomes within one cell, instead of having chromosomes in pairs, polyploid plants have chromosomes in groups of three or four.
Tetraploid plants have groups of four chromosomes per cell. Many breeders have experimented with polyploid and tetraploid plants believing they would produce more potent plants. Polyploids can be induced with applications of colchicine. However colchicine is poisonous and polyploid plants are not more THC-potent, nor do they have any other redeeming qualities.
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!
Choosing from a large and varied plant stock, is the key to successful breeding. There is no guarantee for a breeder, planting only a few seeds, that they will grow into vigorous plants, even if the seeds are from excellent stock. The best solution is to grow many strains to have many plants to choose from.
You can't tell by looking at a plant the exact genes it contains. For instance, a female could have one gene for short stature and one for medium stature, but only medium stature is evident; by looking at the plant you have no way of knowing about the short stature gene. Yet, the gene for short stature is in the cells of the plant and some of the offspring will inherit it, and pass the gene on to their offspring. If enough plants and offspring are inbred, some offspring will be short. By observing enough offspring, a breeder can discern what genes parents have and how they interact.
Environment and Stress
Always give plants the absolute most stable environment possible. Stable environment allows plants to follow their genetic traits without interference. Stress plants by altering the environment and genetic characteristics are affected. Some likely characteristics of environmental stress include abnormal flowers and flowering traits. Often rookie breeders turn the lights out for a day or two or leave the lights on too long after a consistent 12 hour light/dark period is maintained and plants produce abnormal flowers – female flowers with male parts, a stigma protruding from a male flower or female flowers bearing male anthers.
Sex reversal is often result from stressed plants. Sporadic male flowers on a predominately female plant frequently occur on stressed plants. These sexually confused plants are not natural hermaphrodites. They are stressed plants with intersex tendencies manifested as hermaphrodite or monocious plants. Do not confuse these deviations to be a new variety or a hermaphrodite plant. Such plants are the result of stress and not suitable for breeding stock. Had these plants been grown properly, they would be suitable for selective breeding. Stressed plants with hermaphroditic tendencies are generally less potent and low yielding. A person must learn to be a good grower before they can become a good breeder.
Environmental conditions that provoke sexual deviation include photoperiod fluctuation, marginal light intensity, ultraviolet light, nutrient imbalances, cold temperatures, abscisic acid, giberillic acid, old age and mutilation. The world’s top cannabis breeders are good growers and prefer to use naturally occurring genetic traits of plants rather than inducing environmental stimulus to achieve desired results. Altering a plants sex with environmental characteristics could cause the genetic deviation to be picked up by subsequent generations.
Favorable characteristics most breeders look for include general vigor, potency, resin content, flower to leaf ratio, large floral clusters, quality of high – long lasting, soaring, sedative – therapeutic effects, taste and aroma, short stature, early maturation, and mold and mite resistance.
nice post sicc plus rep homie! this will definitely help me throughout my first breed
are male and females predetermined by genetics? some say it is a factor of the environment. this does not hold true in animals/humans why would it in plants?
Yea man its all bout genetics lol
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