I need to correct this to
"mixed"-chemovars, but still, both carry more CBD as THC and are labelled as 'medical' strains. That means that at some point in time the ancestors of these strains had been crossed with a 'high-CBD' chemovar. And these are known to not respond to UVB treatment - as Lydon back then did demostrate.
His original paper actually goes into great length to discuss the various theoretical explanations and these alone give insight into a broader understanding of all the interrelating factors that can trigger a higher cannabinoid content.
The CBD cannabis types originate from East-Europe, even north & middle Asia and these have been separated (by human domestication) already 3 thousand years ago from its original habitate in central Asia.
Most strains today cultivated or sold are actually type-I high-THC chemovars. But most of them are polyhybrids, and there is no proof that all those genetics still are able to respond positively, due to loss of responsible genes. Over decades of "non-UV" HPS or LED cultivation it won't matter. But the science occassionaly still hands out a study or two showing how moderate or pulsed dosis of UVB creates a number of positive effects. The plant can easily repair, compensate the damage (plants do have energy surplus) but what follows in response is a cascade of internal reactive pathways that beneficial. It's a way to induce systemically acquired resistance.
Cannabis Confusion/The History of Afghan/Skunk
THIOLS ENTER THE EQUATION
In 1989, William Wood, a chemist at Humboldt State University (how ironic) discovered that thiols were the key component to the excretion and smell of the North American skunk animal.
Then in 2001, researchers at the University of North Carolina and the University of Gent in Belgium, published research into what makes beer smell skunky. The research showed that beer shares a similar thiol compound to the same one that is produced by skunks. Thiols are a chemical found in humulone, which is a compound found in hops.
From the article in
Discover Magazine June 29th, 2012:
“Shellhammer explains that
when ultraviolet light hits the humulone, a part of the molecule breaks off and binds with the sulfur in the beer, creating the thiol. “If you walk outside with a nice yellow beer like a pilsner on a summer day, the change is happening almost immediately,” he says.
He adds that in Europe and elsewhere, this is known as “light-struck” beer, not "skunky" beer, since skunks are not native to Europe.
Complicating matters is the fact that humans can smell thiols in parts per trillion, Shellhammer says. We perceive the other aromatic components of beer at parts per million. A tiny bit of thiol can overwhelm everything else.
Both hops and
cannabis naturally produce thiols. They also both produce some of the same
terpenes, fragrant chemical compounds, including
humulene (which is not chemically related to humulone), caryophyllene and myrcene.
That’s because hops and cannabis are in the same plant family,
Cannabaceae. If you analyze the oils extracted from each plant chemically, Shellhammer says, they are similar. “When we analyze the compounds in hops,” Shellhammer says, “Sometimes I walk by the lab and it smells like we are analyzing cannabis.””
LINK: Cannabis Confusion/The History of Afghan/Skunk