If you have siblings, you know firsthand how different you may be from them inside and out, despite sharing DNA. Cannabis is much the same way: Even plants that stem from the same cultivar can have a different physical appearance, called phenotype, thanks to genetic diversity and variations in environmental conditions. This diversity impacts the way cannabis grows and the quality of the flower it yields.
What are phenotypes in cannabis?
Phenotypes, often called “phenos,” refers to how cannabis plants of the same cultivar differ from one another in terms of physical attributes, like shape, color, smell, and yield1. Phenotype is the physical expression of a plant’s genetic composition. It’s why certain cultivars grow much taller than others, or why the flower and fan leaves may have a purple-ish tint. In this way, phenos are very much like siblings in a human family — they have similar genetics and may share certain traits, but it’s not hard to find differences between them.
Just because seeds come from the same two parent plants doesn’t mean they contain the same genetic information. When cannabis plants are bred, the female plant produces numerous seeds, each of which contains a unique combination of genes from both parent plants. When grown, the cannabis that sprouts from these seeds will physically express these varying combinations as a particular phenotype with its own set of traits and characteristics.
How phenotype influences dispensary selection
Phenotype is directly connected to cannabis cultivation, but it also has an impact on your selection in the dispensary. Phenotypes offer variety to breeders and cultivators, who can choose the very best versions of each cultivar to produce higher quality flower and increase yields. Through selective breeding of the best phenotypes from different cultivars, breeders create new types of hybrid cultivars that maximize the desirable traits of the parent plants. This means more options, better quality, and an improved selection for you at your next dispensary visit.
What influences phenotype?
Phenotype is influenced by the relationship between a plant’s genotype and the environmental factors in which it is grown. Here’s a closer look at each and how the interplay between them can result in the development of many phenotypes within the same cultivar.
Genotype
While phenotype refers to the appearance of a plant, genotype refers to the genetics that plant contains. Because the combinations of genes passed on by the parent plants are different in each seed, there could be many different phenotypes that emerge within the same cultivar.
Elements of a cannabis plant’s genotype can be passed onto future generations by breeding. When a plant is bred, its genetic profile will be combined with the genes of the other plant and passed on to the seeds in varying combinations. In this way, breeders can select phenotypes with the most desirable traits, such as high yields and potency, and crossbreed them to emphasize those traits even further. Over generations, this process of selective breeding could result in new phenotypes altogether. This is the process used to create new cultivars you’ll find at the dispensary.
Environmental factors
While phenotype and genotype are closely linked, they are not the same. A genotype includes the full range of possible chemical makeup and physical traits of a cannabis plant, while phenotype is the physical expression of the genes that are “activated” based on environmental inputs like temperature, humidity, growing medium, nutrients, and more2. Just because a plant has a certain gene doesn’t mean it definitely will be expressed physically; the environment also plays a role in which genes will be activated and expressed as phenotype.
For example, a plant grown in lower temperatures or higher winds is likely to develop differently than one grown in higher temperatures under a light breeze, even if they have identical genetic profiles. You might notice thicker, bushier growth by the plant grown in lower temperatures and high winds, while the second plant may appear taller and stalkier — each will adapt to its environment despite their identical genetics. It’s much like how identical twins may still have differences in appearance based on their profession, activity level, or where they live.
Cultivators sometimes use the plant’s ability to adapt to its environment to their advantage. Techniques like low-stress training (LST) or supercropping can be used to influence the direction a plant grows, the way nutrients are distributed, and the strength of the limbs.
Environmental factors affect the life cycle of a single plant and will not be passed onto future generations if the plant is bred. For example, if a grower uses LST, low temperature, and heavy airflow to create an especially bushy phenotype that grows wide and short, it does not mean future generations would automatically grow in the same way, even if they are genetic clones of the original plant.
Phenotypes, cloning, and pheno-hunting
Breeders and cultivators generally want to develop seeds and plants that offer healthy growth, high yields, and significant potency in terms of cannabinoids and terpenes, including high-THC or high-CBD cultivars you may look for at the dispensary. Certain phenotypes may offer these traits more than others, so identifying those phenotypes is a high priority for breeders. That’s where “pheno-hunting” comes in.
What is pheno-hunting?
Pheno-hunting is a process used by cannabis breeders to create the best versions of a cultivar with the highest yields and potencies, the best flavors, and the healthiest growth patterns3. This process takes months or years, requiring multiple generations of harvests to examine flower and determine which phenotypes are best.
Once the best possible phenotype is identified, breeders take cuttings from this specific plant to create clones, which are identical genetic copies of the original plant. These clones can then be sold to cultivators who are seeking out the superior genetics of that plant.
Cultivating clones
Clones of highly desirable phenotypes may be kept in the vegetative stage and used to perpetually create new generations of genetically identical clones. These are known as mother plants. Cultivators may keep a mother plant permanently in its vegetative stage so they can continuously take cuttings from it to cultivate more clones, preserving the genetics curated by the breeder during the process of pheno-hunting.
Since clones are identical to the mother plant, if the environmental conditions are kept the same, they will grow the same way every time. Clones allow cultivators to develop repeatable processes and more effectively anticipate yields and potency. Unlike selective breeding, when parent plant genetics are combined at random across every seed, cloning keeps the genotype identical across generations and allows for predictable results.
However, it’s worth noting that even two clones grown in separate environments may end up appearing very different from one another, including in size, shape, yields, and potency4. For optimal results, clones developed for growth in a specific environment should be kept in that environment each and every generation.
Phenotypes: The siblings of the cannabis world
The same DNA doesn’t guarantee that all offspring of the same two parents will look identical. That goes for cannabis plants, too: Two plants of the same cultivar with the same lineage can look remarkably different. This scientific reality is harnessed by breeders and cultivators to their advantage, “training” plants to increase yield, shape phytocannabinoid and terpene profiles, and improve resilience in cannabis plants that grow healthier with each harvest. And while you may not see all the physical differences driven by cannabis phenotype in the dispensary, those attributes all play a role in contributing to the final product you take home.
Sources
- https://leafly.com/news/growing/selecting-a-cannabis-phenotype
- https://dutch-passion.com/en/blog/understanding-cannabis-phenotypes-genotypes-and-chemotypes-n980
- https://leafly.com/learn/cannabis-glossary/pheno-hunting#:~:text=When%20two%20cannabis%20plants%20are,one%20will%20be%20slightly%20different.
- https://royalqueenseeds.com/blog-basic-cannabis-knowledge-genotype-and-phenotype-n265
