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Genotype and phenotype: what makes a cannabis strain unique?

Cannabis genotype, cannabis varieties, genetic traits

Sometimes you like a cannabis strain so much that you want to have it again. Then, when you grow the exact same strain again, you suddenly realise that it looks different from the plants you knew from before. Although it is the same strain, this time the seeds are from a different batch and the appearance of the plants varies. This begs the question: How can this be if it is the same strain? What about the variability?

Two things influence the structure formation of any cannabis plant: genetics and environment. The plant's genetic make-up, or genotype, acts like a blueprint for growth: it allows for a spectrum of physical possibilities, but it is up to the environment to induce (develop from) these traits. The physical appearance of a genotype is called a phenotype. This is defined as the characteristics that environmental conditions draw from the genetic plant code. In short, everything, i.e. colour, shape, smell, resin production and effect of the plant is influenced by the environmental conditions in which the plant grows up.

The appearance and characteristics of a cannabis strain have a lot to do with its evolution, among other things. By the end of this article, you will understand that there are indeed basic characteristics for each strain. But each plant is as unique as a snowflake, expressing its genes depending on its growing environment.

Strains and characteristics

Cannabis is an ancient plant with roots all over the world. The earliest species are thought to have appeared in the mountainous Hindu Kush region of Pakistan, while other species later propagated in tropical climates. These earliest varieties are called landraces, they are the diamonds of cannabis genetics. Over thousands of years, cannabis strains have become increasingly adapted to their geographical location and have expressed this in the form of the best traits.

The shorter, resin-heavy indicas settled between latitudes 30 and 50 degrees, while the large, slow-growing sativas found their home in the equatorial regions around latitude 30 degrees north. These diverse and sometimes very different habitats give rise to a colourful range of cannabis varieties, each with its own long history.

Cannabis cultivation took a major turn in the 1970s and 80s when it was pushed underground from the wild due to government repression. Cannabis enthusiasts worldwide began to grow more indoors. Special electric lights, ventilation and hydroponic systems were used. This produces much of the supply of weed on the market today. Although conditions and equipment have been optimised over the years, grow experts agree that indoor cultivation is at the same time an unnatural environment for plants and that a strain will only ever yield as much potential as is contained in the grow equipment. However, there are now a large number of strains that develop masterfully indoors.

The variety of cannabis has been narrowed down in the course of breeding activities worldwide by selecting and breeding for a high THC content for a long time. Other important characteristics and chemical components such as CBD were neglected. Despite all this, today's cannabis strains offer a great variety of phenotypic characteristics, which are expressed depending on the plant and the cultivation conditions. In the course of cannabinoid research, breeders are now also increasingly focusing on highlighting other traits and cannabinoids.

The following factors determine to a large extent the potential of a plant and thus the potency of the end product:

  • Nutrients, pH value
  • Temperature
  • Height and angle of the light
  • Plant substrate
  • Photoperiod/illumination duration
  • Harvest time
  • Distance of the plants from the light
  • Ventilation, sufficient air exchange
  • Air circulation
  • Humidity
  • Cleanliness in the Growroom
  • Planters with the right and appropriate size
  • Plant density
  • Cultivation methods (SOG, SCROG, low stress training)
  • etc.

Certain growing conditions and factors can promote and induce or inhibit characteristics in indica or sativa dominant varieties. Indicas and sativas have different needs in some aspects of their growing conditions, e.g. nutrient requirements, growth and flowering duration, size of the plant container, etc.

The Age of Hybrids

With the changes in the grow sector and the shift towards indoor cultivation, hybridised varieties began to appear more and more. These are an amalgamation of the world's indigenous strains. The Sativa met the Indica and an ever more branching hybridisation took place. Growers love the Indicas for their resin-coated buds and short flowering time, which are two highly sought-after traits. The mood-lifting, stimulating and euphoric effects of sativa strains are also an important genetic cornerstone. Accordingly, it made sense to cross both cannabis types to get the best of both.

Sativa-Indica

Stability and stabilisation of cannabis varieties

There are various methods for stabilising cannabis strains. Stability refers to the variability and predictability seen in the offspring of a parent generation. If a variety is unstable, its variability is very high and predictability is low. A stable variety develops in a largely similar or even homogeneous way and its later appearance can be predicted well. Predictability in this context refers to the expected distribution between the different phenotypes. In a cross between stable parents, Mendelian inheritance rules state that 50% of the offspring will be equally similar to both parents, while 25% will have more genetic traits referring to the mother and the other 25% will have more genetic traits referring to the father.

Usually breeders and seed banks stabilise a variety over several generations. First, a healthy mother and father are selected and hybrid offspring are produced, which have different predictability depending on the stability of their parents. Then, if the father and mother are sufficiently stable, their offspring show three different phenotypes. Stable parents usually produce predictable, relatively homogeneous offspring with some but manageable variation.

The dominant traits in each parent are recombined to create the genetic basis for the next generation. The first-time crossing of two unrelated parents is called a Filial 1 (F1) hybrid. Typically, the best specimens of the F1 hybrids are then crossed to produce the F2 generation, which is usually slightly less stable than the F1 generation. This is then continued accordingly (F3, F4, F5...) depending on the breeding project and desired traits.

Backcrossing

If brothers and sisters of the same parent are crossed over several generations and selected for certain traits, a higher degree of consistency and predictability can be achieved. The desired traits become dominant and are then always present, while unwanted traits disappear from the gene pool over time. Some traits can be stabilised particularly quickly by backcrossing the plant with previous generations. The use of backcrossing is not necessary for the stabilisation of all traits.

In summary

A variety that is the result of crossing an indica with a sativa, for example, can reflect the whole spectrum of parental characteristics. The environmental conditions, as described above, also contribute a great deal. Thus, in hybridised offspring, it happens that phenotypes of different expression appear in one and the same variety. This does not mean that everything is left to chance, but we should not be surprised if one plant of the same strain does not look exactly like another. Within highly controlled grow facilities and using identical clones (cuttings), identical plants can be cultivated.

Because of hybridisation, we can choose from a seemingly infinite variety of strains and avid strain collectors can hunt for ever new ones.

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