Cannabis Genetics. When we are going to buy marijuana seeds, some growers without much experience do not understand well the different nomenclatures that come in the package of the seeds that they want to buy. Knowing and understanding these concepts will help us choose the seeds that best meet our expectations. There is a big difference between them. It is not the same to grow seeds of a second generation subsidiary (F2) or IBL seeds, as we will see below.
Cannabis genetics. Landraces, also known as pure genetics
What is a landrace? They are the original genetics that grow naturally in some places on the planet. Unfortunately it is difficult to find them since many geneticists (breeders) began decades ago to mix them with other landraces from other places to get new plants with the best of each of the genetics used in the crossing. Knowing what a landrace is one of the most important principles of cannabis genetics.
In the decade of the seventies, many marijuana lovers used to travel through different countries of the world where high-quality indica or sativa varieties grew. Indicas have the ability to develop in very short periods of time. On the contrary, sativas were highly coveted for their cerebral and energetic psychoactive effect, compared to the narcotic effect of indica.
Thousands of young people traveled to exotic countries like India. During the trip they passed through Afghanistan and Pakistan, two countries nestled in the Hindu Kush mountain range. The varieties they found there were pure indica with very short flowering times that also provided a high quality hashish.
Other travelers, especially from California, chose to travel to Mexico and other tropical countries where spectacular sativas naturally grow. The problem with these sativas was that flowering times and their morphological structure were poorly suited for indoor cultivation.
The geneticists got hybrids between indica and sativa varieties in which the plants could have the best of each genetics but with very short flowering times.
Every day it is more difficult to find landraces and in some places, such as Morocco, almost nobody grows them anymore. Although there are still landraces located in places where tourism does not arrive. All landraces belong to one of the 3 cannabis families: Cannabis Sativa, Indica or Ruderalis.
Each variety has its own genes (genotype) that make it develop following certain growth and flowering patterns (phenotypes). The few pure genetics that still remain have the original genotype, which implies great homogeneity in their development under similar culture conditions. The seeds of these pure plants will provide us with very similar plants (phenotype). When we grow the seeds of authentic landraces in the same environment, we get very homogeneous plants whose growth and flowering patterns and their organoleptic and psychoactive properties are very similar between them.
IBL or Stabilized cannabis hybrids
Knowing these types of plants is one of the elementary principles of cannabis genetics. IBL stands for inbred line, which means that plants with the same genotype (inbreeding) have been crossed. Outbreeding is the opposite of inbreeding. Outbreeding occurs when we introduce new genetics into a plant. Geneticists use this type of crossing to fix the best of the genetics used in the crossing without the need of using use another variety, stabilizing the line with which they work. It is the same to do with a hybrid or with a landrace.
A variety is an IBL when a genetic crosses itself. The result of this type of crossing is very stable and the plants that come from these seeds are very similar to each other.
The process to obtain IBL seeds is difficult because the geneticist has had to use many pure copies to make a good selection of the best parents. Perhaps the main problem with this type of genetic crossing is what is known as “inbreeding depression.” This phenomenon is frequent when we cross parents whose genetics are very similar to each other. This also happens with humans and animals. The result is manifested in varieties whose genomes are very similar. Plants will always be very similar in all aspects; from morphology, psychoactive effects, organoleptic properties and others.
When we cross landraces or IBL with genome whose genome is different, we will get what is known as the F1 hybrid, (Parental # 1) which is the first generation of seeds coming from the cross between a certain phenotype of genotype A with another phenotype of genotype B ( Parental # 2).
This type of crossing produces homogeneous plants, if the parents we have used in the crossing are stable. When we cross different landraces or IBL, we obtain very strong plants (F1 hybrid) since they develop the so-called “hybrid vigor” or heterosis, which is the opposite of inbreeding. The result translates into better copies. To be clear, we call F1 the first subsidiary generation of any cross between pure races or IBL.
We can also cross copies of the F1 generation among themselves (whether they are pure, hybrid or polyhybrid varieties). In this way we obtain the second subsidiary generation, which is known as F2, and so on without limits. Often the second generation F2 subsidiary produces a less homogeneous offspring than the first. Often we will obtain 25% of plants similar to the mother, 25% of plants similar to the father and 50% of plants whose genetic information is a mixture between both parents. To obtain very stable plants, we must continue crossing generation after generation (F3, F4, F5 …) and the time will come when we will obtain a very stable offspring in which the most desirable properties that are sought have been stabilized. Many seed banks are so eager to present new varieties in their catalog that they skip part of the tedious and arduous stabilization path. Seed banks know that this process is one of the elementary principles of genetics, but they still choose the shortest path.
Almost all the seeds we can buy today are “polyhybrids”, the cross between hybrids. The problem with this crossing is that the offspring are often not very homogeneous and the plants we grow are very different from each other. The genome of these plants is very varied and therefore they do not usually give plants as homogeneous as those from the classic F1 hybrid. It is not difficult to understand the complexity of stabilizing such a cross, since the mixing of the genetic traits of the different varieties used to achieve the new genotype is very complicated. It is difficult to select and above all, stabilize the traits we want to keep. Almost all of the hybrids available in cannabis seed banks are polyhybrid; plants that come from the crossing of two hybrids, and homogeneity is difficult to achieve.
The backcross is another of the most elementary principles of cannabis genetics. The backcross is the technique that geneticists use to set the most desirable characteristics of one of the parents used in the crossing. They choose a copy of the offspring of the crossing (it can come from any generation, F1, F2, etc.) and cross it with the original parental of which they want to fix the characteristics. This parental is known as recurring parental. With this technique, geneticists set the best characteristics of the original parental by crossing with their own offspring. If what we want is to obtain an offspring more similar to the chosen parental, we can cross the first generation obtained, the BX1 generation with the same parental, with which we obtain a BX2 or squaring. We can repeat the operation for the third time (BX3 or cubing) or even as many times as necessary to achieve good results. This repetition would result in BX4, BX5, and so on.
Geneticists use this technique to replicate plant clones when they don’t have males and want to get seeds. We select a donor parent (male) that allows the desired characteristics of the female clone to be expressed in their offspring, and repeating the backcrosses as many times as necessary to achieve the desired goal, which is a offspring with all the desirable characteristics of the original mother you want to replicate.
S1 stands for the first generation of a branch of a female plant by itself. Different techniques can be used and when done well we get seeds that give plants very similar to the female that you want to replicate, and the seeds are also female. Thus, we reverse the sex of a clone of a female and use her pollen to pollinate her.
The more stable the replicated female, the more stable the results. We can use this technique with the same objective that we use the backcross between female and male plants, selecting and setting the most desirable characteristics. But in the case of the S1 we use a single female parent to which we reverse sex to produce the first generation. We can find seeds S2, S3, etc, or backcrosses made from generation S1, S2, etc., again with the original female plant.
No doubt this type of technique constitutes another of the elementary principles of cannabis genetics that a grower must know.