While outdoor cultivation is more sustainable, indoor cultivation provides a more precise control of the environment. But what exactly are the effects on the cannabis plants themselves? Two cannabis growers have collaborated with Columbia University to compare the differences in natural and artificial cultivation. The study compared the metabolic profile of commercial cannabis from two different cultivars, grown indoors using artificial light and artificially grown media, with samples having identical genetics but grown outdoors in living soil with sunlight. "We found that in general, the sun-grown samples have less oxidized and degraded cannabinoids and more terpenes (quantity and type of terpenes), particularly the sesquiterpenes, than the genetically identical commercial samples grown indoors."
The study
Two commercial cultivars of cannabis were analyzed, Red Velvet and Cheetah Piss. The outdoor samples were part of the 2021 seasonal and commercial grow by Ridgeline Farms. The indoor samples were grown commercially in 2021 from clones of the same genetic stock as the outdoor samples. The indoor samples were grown by grandifloragenetics.com for RV and by cookies.com for the CP samples. The outdoor samples were grown in raised beds using a proprietary mixture of all-natural soil and composts under full sunlight. The indoor samples were grown under artificial light in a proprietary growth medium.
More terpenes outside
Overall, the study found that the outdoor cannabis samples had a greater diversity of terpenes and greater amounts of the ones that are present when compared to indoor cannabis from the same genetic stock. "Moreover, the outdoor samples have a greater preponderance of sesquiterpenes relative to the indoor samples. Therefore, in-depth metabolomic evaluations of cannabis terpene profiles grown in different conditions are important, given their potential medicinal and therapeutic values. Moreover, our results suggest that the remarkable differences in the terpene compositions may be a reflection of indoor growers not optimizing growing conditions for terpenes that do not appear in the California testing. It has been well documented that terpene levels in cannabis have been declining over the past decade or so."
More degraded and oxidized cannabinoids indoors
According to the researchers, it is not clear why the indoor samples produce more degraded and oxidized cannabinoids. "However, this could be related to the synergism that the plant has evolved throughout its history. One of the terpenes' functions in the plant is to act as an antioxidant and can also protect the plants from pest damage. When grown indoors in a controlled environment, we found that the terpenes are not expressed in as high an amount. Therefore, there is less of an oxidation shield provided to the flowers in indoor cannabis. This could account for the increased levels of oxidized and degraded cannabinoids in indoor samples. For example, the sesquiterpenes and cannabinoids are produced on different biochemical pathways, and we found that several metabolites related to the sesquiterpene pathway are accessed more effectively in outdoor cultivation. In parallel with this, outdoor plants are able to express the totality of their biochemical pathways. Terpenes can act synergistically with variations in quantities and ratios and in combinations with other bioactive secondary metabolites such as cannabinoids, as suggested by the varied medicinal effects, known as the 'entourage effect.' This synergy could be significant in cultivating and breeding cannabis with greater therapeutic benefits."
To read the complete study, go to www.mdpi.com