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Practical Grow Room Genetics

Did you know that DNA stands for deoxyribonucleic acid? Odds are pretty good you did, even if you might need an Internet connection to be sure you’re spelling it right, but why is that? Why is this particular scientific name so popular when others like isoamyl acetate (artificial banana flavoring) remain obscure? It’s because DNA has been popularized for decades, as the gold standard of undeniable evidence in forensic crime dramas, and the thing that every mad scientist messes with to create the monster in science fiction movies.

In much the same way, scientific names like delta-9-tetrahydrocannabinol, and cannabidiol are coming into regular use, for similar reasons. For the cannabis consumer, there is a practical value to understanding the ratios of cannabinoids by name, and that goes double for cannabis growers. There’s a lot of ways we can benefit by looking at our plants with a scientific eye: greater consistency, greater potency, more hardy plants. So read on, and let’s refresh ourselves on a little basic science, and see how it applies to your grow room.

First, let’s get a few things cleared up. We can all remember our high school biology teacher telling us about genetics. Two parents mix their DNA, and some combination of their genes get passed to the resulting children as a genotype. However, some genotypes are hidden and do not get expressed as phenotypes, which are an organism’s detectable characteristics. This can happen for a number of reasons, the major one being that some traits are dominant, and some are recessive.

Side note: You may have already heard the word phenotype, or ‘pheno,’ used to refer to a particular plant. That’s a definition of the word that’s particular to the industry, and in that context, it’s perfectly valid. But if you’re talking with a scientist, they’ll expect phenotype to refer to a plant’s characteristics, not the plant itself.

For example, let’s say that a child with brown hair has a father with brown hair and a mother with red hair. Even though the kid has the phenotype of brown hair, we can deduce that they have the genotype for red hair as well, because red hair is a recessive gene. If the mother had anything other than two sets of red hair genes, she would not have the phenotype of red hair, so she can only pass red hair to her kid.

Here’s where it gets interesting. Some traits will only become phenotypes if the right environmental circumstances are met. We see simple examples of this all the time. Someone is born with the genes to be six feet tall, but they only grow to be five feet six inches tall, because they were malnourished as a child. You may have already seen this in your own grow room. If one of your plants isn’t getting the right nutrients, and its leaves begin to yellow or curl, that response is an example.

This is where the science of genetics gets practical. Every grower is looking to get the best phenotypes expressed in their plants while avoiding undesirable phenotypes. To this end, we weed out the males to ensure that our females grow ‘sinsemilla’ or without seed, producing larger, more potent flowers.

We train our plants to maximize the number or size of buds they produce. We feed them, water them, fill our grows with light, and generally keep a tight hold on their environment to pamper them as much as we can. We optimize all of these factors with the goal of getting the best we can out of our plants, but we can’t do any of that unless we know what we’re growing.

Knowing what we’re working with starts with sourcing. For indoor growers, cloning is the most common method of starting out a new crop, while many outdoor growers prefer starting from seed. In both cases, you’re probably getting them from an outside source, and if you are, there are some questions you’ll need to be able to answer.

First, who are you buying from? Some receive their seeds or cuttings as a favor from a friend, but for those without such good fortune, a cottage industry has sprung up. Joey Erinata, cultivation director for Sparc, a cannabis growing company in Rohnert Park, California, estimates that around 1 in 1,000 growers are producing seeds for other growers and developing new hybrids. “It is becoming a new industry,” he said. “It’s mostly in Northern California that you see it going on, at least here in the U.S.”

So if you’re going to one of these specialists to get some fresh genetics for your grow room, what do you need to know? First, you need to know what genes you’re getting. There are landrace strains, which are indicas and sativas that grow naturally all over the world, but there are also heirloom variants of those strains, and many other kinds of hybrids as well. Some hybrids are mixed with genes from the less common ruderalis strain to be autoflowering.

The plant’s genetic heritage can give you some clues about what to expect once it’s planted. You should be able to get some guidelines from your seed or clone supplier on how long it will take to flower, the light range it tolerates, and its ideal feeding schedule. However, these guidelines can be hit or miss, and should only be used as a jumping-off point for your own environmental tuning.

There are other elements to consider than a seed or clone’s strain as well. If the seed has been feminized, that means the grower took a female plant, stressed it until it became hermaphroditic, and then used the pollen it produced to get seeds that are much more likely to grow into females than males. However, this can also result in females that are more likely to become hermaphroditic under stress, which puts your grow room at risk.

Another question to ask is whether or not the seed been stabilized, and if so, how much variation are they seeing from it? Breeders can stabilize a particular strain by breeding it with closely-related plants (crossing) or even the plant’s own parents (back-crossing). A seed stock that’s been stabilized like this produces their characteristic phenotypes more consistently.
If the dispensaries you sell to have a few strains that are consistently popular, paying for stabilized seeds of those strains is probably a smart investment. However, there’s a risk to only focusing on the most popular options. Even if what’s popular in your region doesn’t change much from year to year, the retailers want to cover their edge cases too.

“The demand from retailers is for a combination of the tried and true varieties that they know are the best sellers and the unique differentiating varieties,” said Erinata. “So they have some new, fun, adventurous thing to interest new and returning customers alike each time they come in.” Catering to this desire for novelty can be a good way to distinguish your brand.

But there’s a central problem you’ll need to overcome first. That is, seed stabilization takes time and effort, so only the most popular strains are likely to be available in stable forms. You can buy a hundred seeds of some more esoteric strain from a grower, but you’re likely to get a wide range of phenotypes, with some seeds growing hale and hearty, while others do not.

You can nail these down through a simple process known as pheno hunting. I’ll let Tom Scoble, founder of Mother Magnolia Medicinals in Eugene, Oregon, explain how it’s done. “Let’s say we drop 50 seeds of a particular genetic and we weed out the males, so we’re left with 25 females,” Scoble said. “We let those 25 females grow big enough that we’re able to take cuttings off of all of them. Everything is all labeled and categorized and tagged. We take six cuttings from each, and then we let the mothers flower, to see what they can do.”

During the vegetative stage, the plants are already giving important indications of their phenotypes. Some are growing taller than others; some are responding better to the stress of having cuttings taken. Those factors speak to the plants’ resiliency, but we care most about the quality and quantity of bud they’ll produce, and we can’t know that until they flower.

Scoble takes note of the plants’ structure and how the flowers look, but he doesn’t make any decisions about which to keep until the buds they produce come back from the lab. “The labs inform us on the back end, tell us what’s actually embedded in our buds and whether or not each plant is worth keeping.”

The cuttings from the most successful plants have already been dipped in a rooting hormone and turned into clones. If a plant produces inferior bud, its clones are removed, and the process repeats.

The process is distinct from breeding because no genetics are being mixed between generations of plants. We’re choosing the clones that express their phenotype well in our grow, not creating new genetics that are likely to express desirable phenotypes.

A few rounds of this winnowing process will result in very consistent-growing plants, that can then be a staple of your crops. The added bonus being that in the time you’ve spent pheno hunting, you’ve already done much of the fine-tuning to find the ideal growing conditions for your clone.

However, for all that pheno hunting promises, don’t forget that it carries risks as well. “If it is a variety that’s new to you, there is that level of the unknown,” Erinata warned. “With a clone plant, it’s generally known whether it’s prone to being hermaphroditic, or prone to getting powdery mildew. Those are technically physical characteristics, and part of the pheno-hunting process.”

If the strain you’re pheno hunting with is prone to change sex under stress conditions, every plant that’s in range of a potential pollination is at risk. “There are certain strains, or even phenos, that instantly become hermaphroditic under even low-stress conditions,” Erinata said. “One random little node that you don’t necessarily catch, and you risk not just pollinating your test room, but your cash crop.”

One way to avoid this is to physically separate your testing/pheno hunting area from your main growing room. However, that isn’t a feasible option for everyone. If you can’t afford a separate area, your state’s laws limiting grow areas make it impossible, or you’re simply growing everything outside, you may have to take other precautions to avoid a disaster.

Of course, while there are risks inherent to pheno hunting, there are also risks inherent to doing nothing at all. You’re limiting the diversity of your cash crop to what your supplier has to offer, and whatever you can clone on your own. “A big problem in the cannabis industry right now, across the country, are the diseases that are being spread via clone propagation,” said Erinata.

If you haven’t heard the name Fusarium oxysporum, you will sooner or later. “It is a systemic, fungal pathogen that travels through or breaks down the vascular tissues of the plant,” he explained. “It cannot be eliminated without cutting down or removing the plant and discarding the infected soil. If you have any kind of fungal gnats or other pests in the room, they can very quickly spread this pathogen from one plant to the next.”

If you’re growing nothing but clones of a single plant, then anything that feeds on or infects that one pheno will be just as bad for your entire crop. One way companies can protect themselves from this eventuality is by building up a seed bank. Generating and storing some seeds from every strain or crop you grow gives you stock to grow from in the event of a catastrophe.

In the long run, it’s also handy for insulating yourself from the vagaries of strain popularity. Let’s say Gorilla Glue is flying off the shelves this year in your area. After a few years, Gorilla Glue sales slump, replaced by Bubba Kush, or Sour Diesel. You store your seeds and start growing other strains. If three, or five, or eight years down the road, Gorilla Glue starts making a comeback locally, you’ll be one grow cycle away from capitalizing on that demand.

Seeds can wait for months, years, or even decades if stored properly. Spider mites, or fusarium, or heck, even a wildfire, comes through and knocks your yield down to zero, they’ll still be waiting to sprout.

For all that we’ve discussed here; genotype and phenotype, cannabis breeding and pheno hunting, safety and seed storage, this is still a brief overview of what we can learn from genetics. Scientific research on cannabis is still in its infancy. “What we know today about the effects of terpenes is just scratching the surface compared to what we will know in 20 years,” predicted Scoble. “They’re unknown compounds right now, but we know that they are synergistically, inextricably related to the cannabinoid profile in the flower.”

Right now, when we get the results of a lab test on our flowers, it tells us the potency number, the cannabinoid profile, and the terpene profile. Right now, we can only guess at how they are interrelated, and the effects they’ll have. When we know more, it’ll be because of genetics, so in that sense, genetics is as vital to the future of this industry as it is to its present.

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