this guy gives a great breakdown on cannabis breeding, it would be an enormous amount of work, but if one has the passion then i feel it could a joy to do so!
copy and pasted from the grasscity forums, here:
http://forum.grasscity.com/absolute-beginners/387690-what-ibl-strain.html
fadervader breaks it on down:
Breeding and growing cannabis 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.
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.
copy and pasted from the grasscity forums, here:
http://forum.grasscity.com/absolute-beginners/387690-what-ibl-strain.html
fadervader breaks it on down:
Breeding and growing cannabis 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.
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.
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