Two years ago one analytic chemistry lab had begun testing Cannabis buds for potency in California, and one strain had been found to contain more than 4% Cannabidiol (CBD) by weight. Today there are at least 10 labs serving the industry in CA, Colorado, and Montana, and more than 25 CBD-rich strains have been identified (See list at right).
Dedicated plant breeders aspire to produce strains stable enough to enable seed sales. As one skilled breeder reminds us, "stabilizing the genetics... is not just a simple F1 Hybrid between two parents that may or may not have the desired traits. Stabilization could take as many as five or six inbred generations beyond the original F1 cross to establish a homozygous gene condition for CBD."
We asked the dean of West Coast plant breeders, DJ Short, to define his standard of stability. "If you cross it with itself, you get pretty much the same thing," he replied. DJ guarantees that at least 2 females (and 2 males) in your pack of 10 will display or exceed the advertised characteristics. That means half the seeds, based on an 80% sprout rate. DJ says he could cross more generations and approach 100% replicability, but he knows the buyers would rather have access now, on the two-out-of-10 basis.
Lawrence Ringo of Southern Humboldt Seed Collective informs us that he has stabilized the CBD-rich Sour Tsunami strain and will make seeds available as of March 1!
The Marketing of Cannabidiol
Given the huge potential market for less psychoactive and non-psychoactive Cannabis, the introduction of CBD-rich medicine at the dispensary level can be seen as rather slow. Many dispensary owners have been reluctant to stock CBD-rich strains because their present customers are seeking —or are not adverse to— Cannabis that provides euphoria or sedation. In other words, THC content sells, it's a sure thing. Why should a dispensary spend money and devote shelf space to a type of Cannabis that most medical users haven't heard of and whose effects are unproven? Growers, in turn, have to anticipate the wants of dispensary buyers, and are reluctant to devote precious garden space to plants for which there is no established market.
Demand at the dispensary level might not take off until effectiveness is established. Which might not happen until significant numbers of patients have tried CBD-rich Cannabis and taken the SCC survey to report their results.
Why the Occasional CBD-rich Strain?
Why does it happen, that after generations of breeding Cannabis to maximize THC, about one in 500 samples tested by the labs is found to contain 4% CBD or more? This is one of many questions we hope to answer. A friend is convinced that a mutation gave rise to his True Blueberry x OG Kush cross, which typically contains 10% CBD or more. "Neither parent stock had CBD," he notes. It took a series of crosses and parent selections to produce his blue-ribbon strain. When and where would such a mutation occur? As the Cannabis plant matures, the common precursor to both CBD and THC is a molecule called cannabigerolic acid (CBGA).
CBGA is turned into CBD acid and THC acid by enzymes called CBDA synthase and THCA synthase. A mutation resulting in excess CBDA synthase or deficient THCA synthase would result in CBD-rich offspring.
We hope to track the similarities and differences reported between strains with similar cannabinoid ratios. Harlequin, Jamaican Lion and Omrita Rx3, for example, have been tested several times by several labs and are in the neighborhood of 8-9% CBD and 5.5-6% THC —about a 3:2 ratio. And yet anecdotal evidence suggests differing effects. We have only taken the first step on a long march towards understanding.