Today there is a large variety of cannabis strains. Some of the most popular and genetically stable strains of marijuana are the F1, F2 and IBL (In Bred Lines). Today we will focus on IBL's and get into filial generations in a later post.
In Bred Lines or more popularly known as IBLs, are mated among themselves with the goal of stabilizing the strain. Some famous in bred line includes Northern Lights, Big Bud, Skunk #1, Hindu Kush, Afghani #1, Thai and Columbian Gold. When you try breeding and mixing at least two of the strains mentioned you will initially produce F1 or Filial Generation. F1 strains are very consistent and powerful potency since they have strong genetic components rooted from its maiden parents. When you start breeding F1 from other marijuana strains, you will produce F2. When you continue breeding your filial generation, your strain will most likely be exposed to probable unanticipated characteristics. As per our reference, IBL or In Bred Line is homogenous in nature and they are genetically cultivated consistently and is less likely to hermaphrodite.
Here is an example in action:
Imagine that a breeder has two strains: Hindu Kush and Skunk #1. This means they want to create a plant that is homozygous for the following traits and call it something like Hindu Skunk. The breeder selects traits for breeding like pale green leaf, hashy smell, flowers with large crystals, and short plants.
All the genetics needed are contained in the gene pools for Hindu Kush and Skunk #1. 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 "Hindu 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 Hindu Kush for starters. The breeder will grow out as many Hindu Kush 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.
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, and that is extremely difficult.
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 Hindu Skunk 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.
Next week we will discuss filial generations.