Cannabis Genotypes, Chemotypes, and Phenotypes

Cannabis has gained widespread popularity, yet its complexities often remain misunderstood. At the heart of this plant’s diversity are its phenotypes and variations, which are essential in determining its effects, flavors, and growth characteristics. By exploring the different types of cannabis and their unique traits, we can gain a deeper understanding of how to choose the right strain for our needs and preferences. First, let’s break down some basic terminology related to cannabis phenotypes!

What’s a Genotype?

A genotype in cannabis plants refers to the genetic makeup inherited from parent strains, which is vital for determining growth patterns, yield, cannabinoid and terpene production, and resilience to both pests and diseases. For breeders and cultivators, understanding genotypes is essential as it helps predict the inheritance of desirable characteristics through generations, facilitating the development of better strains and improving cultivation outcomes.

What’s a Chemotype?

A chemotype refers to the chemical composition of a particular strain, specifically the profile of cannabinoids, terpenes, and flavonoids it contains. Each chemotype can exhibit distinct effects and medicinal properties, influencing how the plant interacts with the body’s endocannabinoid system. For example, high-THC strains may produce more substantial psychoactive effects, while those with higher CBD content may offer therapeutic benefits without intoxication.

What’s a Phenotype?

The term phenotype represents the observable variations or physical expressions in plants of the same strain. When growing several plants from the same cannabis seed pack, variations arise due to genetics, environment interaction, and cultivation methods. For instance, an individual plant of the same strain may exhibit notable physical differences when grown indoors versus outdoors. A common variation is anthocyanins, where buds can develop a purple phenotype in colder climates.

Plants cultivated in ‘living soil,’ rich in organic matter and microorganisms, often exhibit a more complex and vibrant terpene profile. This is primarily attributed to the diverse microbes in living soil, which can enhance nutrient availability and uptake. In contrast, plants grown indoors, typically under controlled conditions and synthetic mediums, may lack the same level of terpene diversity, missing out on the wide range of natural interactions in a living ecosystem.

Why Recessive Alleles Matter to Breeders

Understanding how these genetic principles work can explain why recessive alleles are so significant for breeders. In cannabis genetics, recessive alleles must be inherited from both parents for specific phenotypes to manifest. A plant with one dominant allele and one recessive allele displays the dominant trait, while the recessive remains hidden. Recessive alleles influence plant traits like leaf shape and color, cannabinoid content, and terpene profiles.

Photo: Full Moon Farms / Erik Christiansen

Genetic code variations among different seeds or strains can significantly influence the expression of phenotypic traits in cannabis. Even seeds from the same genetic lineage may exhibit slight differences that impact growth patterns, yield, and unique plant characteristics. This variability emphasizes the crucial role of genetic diversity within cannabis seed polations, ultimately affecting quality, potency, and the overall cultivation experience.

So, what plant phenotype examples are breeders looking for?

Pheno-hunting: The Best of the Best

Exploring these variations in phenotypic expression is commonly called “pheno hunting.” This process involves carefully selecting and identifying plants based on their unique traits, such as flavor profile, aroma, or growth characteristics. Breeders often conduct extensive evaluations over multiple growing cycles to isolate and cultivate the most desirable phenotypes, which can lead to the development of new strains with enhanced qualities and attributes.

Photo: Full Moon Farms / Erik Christiansen

Each year, Humboldt Seed Company embarks on an extensive pheno hunt, evaluating thousands of cannabis plants across Northern California. This multi-week event unites expert farmers, enthusiasts, and industry leaders to identify standout strains with unique traits, such as vibrant colors and robust structures. By prioritizing stable genetics and pest resistance, they ensure the cultivation of superior, high-quality seeds for both commercial and home growers.

Breeders evaluate flavor profiles, terpene diversity, resin production, and growth characteristics. Over multiple growing cycles, they document variations to select the best phenotypes, enhancing their plant breeding programs and developing superior strains. A key aspect of this process involves closely monitoring the filial generations, as these descendants provide essential insights into traits that inform future breeding efforts.

Filial Generations

The concept of filial generations refers to the successive generations that result from the breeding of organisms, particularly in genetics. The initial generation is called the parental generation (P), and the offspring produced from this generation are termed the first filial generation (F1). If you further breed the F1 generation, the next set of offspring will be the second filial generation (F2), and so on. We’ll touch on this in just a minute!

So, you might wonder how the filial generations affect pheno-hunting, and that’s simple! Understanding the inheritance patterns in filial generations allows breeders to predict and select offspring with desirable characteristics effectively. For example, if a particular attribute is expressed strongly in the F1 generation, breeders may focus their efforts on the F2 generation, where more significant variability and potentially new characteristics emerge.

F1 seeds

F1 seeds represent the first filial generation produced by crossing two genetically distinct cannabis strains. This crossing results in plants exhibiting hybrid vigor, which refers to their enhanced growth rate, health, and resilience compared to their parental strains. True F1 seeds are remarkably stable and reliable, stemming from breeding two highly-inbred lines, minimizing genetic variability and maximizing yield.

F2 seeds 

F2 seeds are derived from the second filial generation, which results from crossing two F1 seeds. This generation tends to show increased genetic diversity, which can introduce a broader spectrum of plant characteristics. While this variety can lead to unique and interesting cannabis phenotypes, it can also result in less uniformity in growth patterns, plant structure, and other variances than the more consistent F1 seeds.

True F1 

True F1 refers to F1 seeds created from the cross between two highly inbred and genetically distinct strains. These seeds are renowned for their stability and predictability, ensuring that their attributes, such as flavor, potency, and growth patterns, are consistent and reliable. 

S1 seeds 

S1 seeds are produced by crossing two similar genotypes instead of distinctly different strains. This method yields seeds that preserve more of the genetic traits of the parent plant. As a result, S1 seeds typically show less genetic variability compared to F1 seeds, which can lead to more uniform growth and predictable attributes. However, the limited genetic diversity may also restrict adaptability to unpredictable climate variation.

Photo: FooDoo Farm

Phenotypic Instability: The Difficulties

Inconsistent phenotypes within a breeding line pose significant challenges for growers and breeders. When traits vary widely from seed to seed, it can lead to unpredictability in the final product, affecting qualities such as yield, flavor, and potency. This inconsistency can complicate growing strategies, as cultivators may struggle to replicate successful harvests. Additionally, it can undermine the market appeal of specific strains, making them less desirable to consumers.

Several factors contribute to phenotype instability, including genetic diversity within the breeding line, environmental influences, and the methods employed, such as backcrossing or selfing. If genetic variations are not evenly stabilized, the result can display an unpredictable array of traits. This instability complicates breeding efforts and affects growers’ confidence, necessitating meticulous breeding practices and extensive testing to create stable and uniform strains.

Practice makes perfect!

FAQ on Cannabis Phenotypes & Variations

What does phenotype mean?

A cannabis phenotype refers to the observable traits of a cannabis plant.

What is a cultivar?

A cultivar is a specifically bred and selected variety of cannabis with distinct genetic traits maintained through cloning or breeding.

What is a strain?

A strain is a commonly used term to describe a specific variety of cannabis with unique effects, flavors, and growth characteristics.

How do phenotypes affect cannabis effects?

Phenotypes influence cannabinoid and terpene production, which impacts the plant’s effects.

How do genetics influence weed phenotypes?

Genetics determine the characteristics a cannabis plant can express—however, environmental factors like light and temperature often influence which traits are most dominant.

Can the same cannabis strain have different phenotypes?

A strain can exhibit different phenotypes based on its growing conditions. Some plants may display a vibrant purple phenotype, while others from the same seed pack may appear, smell, or affect users differently.

What is pheno-hunting?

In cannabis cultivation, pheno-hunting refers to the practice of growing multiple seeds from the same strain to identify and select the most desirable phenotype. This selection is based on desirable plant traits such as potency, yield, flavor, and resistance to pests or diseases.

Why does cannabis from different regions have distinct phenotypes?

Landrace strains from different regions have adapted to specific climates, developing unique phenotypic traits based on their environmental conditions over generations.

Can cloning preserve a cannabis phenotype?

Yes, cloning a plant ensures the new plant is genetically identical to the original, preserving the best cannabis phenotypes. However, environmental factors can still cause slight variations in plant growth.