Growing marijuana is a lot more technical than just watering a plant. The components CBD and THC appear in different amounts in crops and if a crop exceeds federal THC levels, it must be destroyed.
THC levels peak at the plant’s maturity and can catch growers off guard. A University of Minnesota-led research team is hoping a genetic test will be able to predict THC in cannabis plants versus CBD.
“We validated a simple genetic test that can predict whether a plant will produce mostly the CBD or THC molecule, using a variety of Cannabis sativa plants,” said George Weiblen, who is a professor in the College of Biological Sciences and the Science Director & Curator of Plants at the Bell Museum. The research team, led by the Weiblen Lab, published their findings in the American Journal of Botany.
The research team studied three different varieties of Cannabis plants from industrial hemp growers, wild or feral cannabis, and marijuana samples from the National Institute on Drug Abuse.
The team then compared genetic markers with the ratio of THC versus CBD and verified that genetics were a good predictor of the ratio.
Depending on the THC level, Cannabis plants earn the title of “hemp” or “marijuana.” The team has proposed using the ratio of THC to CBD to separate THC-type plants from CBD-type plants.
The wild cannabis had contained both CBD-type and THC-type plants. Weiblen notes that finding THC-type plants in a field of ditch weed is rare, a 1 in 100 chance. The THC levels are also much lower than what marijuana users are seeking.
“We hope this new test can assist in new seed certification for the hemp industry,” said Weiblen. “For hemp to take off in Minnesota and elsewhere, there must be ways to assure growers they won’t have to destroy their crops at the end of the season.”