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Marijuana – Male or female cannabis grown for illicit drug use

While cannabis has been reported to contain over 500 different compounds (546 compounds as of last count) belonging to a diverse group of chemical classes, the most important of which is the cannabinoids (104 cannabinoids) (5), the potency of cannabis is usually judged based on the THC content of the preparation. Other constituents do have pharmacological properties of their own, but are not the subject of this report.

The first Potency Monitoring (PM) sample was received for analysis in 1975. In past years, confiscated marijuana samples were sent to the project from National, State, and Local law enforcement agencies, but due to funding restrictions, only samples from the DEA regional laboratories are processed for analysis as of August, 2010. A database to record information of each sample was established by the University of Mississippi School of Pharmacy data center. These samples are assigned a PM number by the database. Information such as seizure location (city and state), seizure amount, seizure date, case number, exhibit number, and identification of type of sample (bud, sinsemilla, kilobrick, maturity level, hashish, hash oil, etc.) are entered to describe the sample. At present, there are 54 fields of information entered to describe each sample. The samples are then prepared for analysis. Technological advances over the years have made it possible to increase the information recorded for each sample. The most recent database is on the web and can be viewed by a selected group. It also has the capability to be downloaded into a program e.g., excel, making it possible to prepare graphs and tables. The database program also has the capability to prepare many of the reports required by the Natonal Institute on Drug Abuse (NIDA) and other federal agencies.

Samples

It is concluded that there is a shift in the production of illicit cannabis plant material from regular marijuana to sinsemilla. This increase in potency poses higher risk of cannabis use, particularly among adolescents.

Hashish – A concentrated resin cake or ball produced from pressed kief, the detached tricomes and fine material that falls off the cannabis flowers and leaves. It varies in color from black to golden brown depending on the purity and variety of cultivar it was obtained from.

Thai Sticks – A form of cannabis from Thailand consisting of premium buds of seedless marijuana in which the leaves and buds are tied on the stems to secure the plant material.

Samples in this report are received over time from DEA confiscated materials and processed for analysis using a validated ‘gas chromatograph with flame ionization detector (GC/FID)’ method.

Cannabinoid concentrations from the lower canopy of crop cycle two are presented in Table 2. Lower canopy concentrations of Δ 9 -THC, total Δ 9 -THC, and their biosynthetic precursor Δ 9 -THCA were significantly increased under RGB and Red-Blue SCL treatments compared with the control. Concentrations of CBDA, total CBD, CBG, total CBG, and CBGA were not significantly different between treatments.

Controlled environment chamber schedules for the various production phases of cannabis.

Red-Blue and RGB SCL treatments significantly increased dry bud yield in the second crop cycle, whereas only RGB SCL significantly increased yield in the first crop cycle (Fig. 3). This was expected due an overall greater amount of light being delivered to the plants in these treatments relative to the control treatment (Peat, 1970; Ralph and Gademann, 2005; Stasiak et al., 1998). Furthermore, the additional light energy was being delivered to leaves that would have otherwise been shaded by upper canopy leaves. Regardless, it is notable that Red-Blue and RGB SCL treatments increased yield by 19.8% and 24.5%, respectively, relative to the control in the second crop cycle, which is a disproportional yield enhancement with the RGB treatment given that the SCL only contributed an additional 19% greater PPFD measured at midcanopy than the control treatment. By contrast, in the first crop cycle the RGB SCL treatment increased yield by only 18.9% relative to the control treatment. Below the point of light saturation and limitations of water, CO2, or nutrition, increasing the intensity of light generally increases photosynthesis, and ultimately yield, proportionally (Stasiak et al., 1998). The disproportionate increase in yield via SCL may be explained by improved light distribution and penetration into the lower canopy than what would be available by simply increasing the overhead PPFD. The difference in yield enhancement between crop cycles one and two may be explained by the second crop cycle having more vegetative tissue in the lower canopy; in the first crop cycle, leaves and branches were pruned from the bottom 20 cm of the stem, which is a common practice (gyping) in cannabis production. Gyping was omitted from the second crop cycle with the rationale that lower-canopy leaves, which normally would receive relatively little light and therefore contribute very little to whole-plant photosynthesis and biomass production, may be of greater photosynthetic value when growing with SCL. Future studies with lights positioned above and to the sides of the plant canopy are planned to address this further.

Results and Discussion

In the upper canopy of crop cycle two, there were no significant differences in cannabinoid concentrations between treatments (Table 2); however, there were detectable differences in terpene profiles (Table 2). Alpha-pinene, limonene, myrcene, and linalool were present at significantly higher concentrations in the RGB SCL treatment than in the control treatment, whereas cis-nerolidol concentration was significantly higher in both Red-Blue and RGB SCL than in the control (Table 2).

Ratio of bud to nonbud (stem and leaf) tissue. Plants were grown with no subcanopy light (control), Red-Blue, or Red-Green-Blue (RGB) subcanopy light. Vertical bars indicate standard error. Horizontal disconnected bars indicate significant differences between treatments using Tukey’s multiple comparisons test, α = 0.05.

Cannabinoid and terpene content in dehydrated cannabis bud tissues. In crop cycle 1, 5.0 g of dehydrated bud tissue was randomly sampled from all bud tissue in a given treatment and replication; in crop cycle 2, bud tissue was similarly sampled, but buds were distinctly sampled from the upper and lower plant canopy. Different letters indicate significant differences between treatments in a given sample set using Tukey’s multiple comparisons test, α = 0.05. Asterisks in place of values in crop cycle 1 indicate unmeasured compounds.

Citation: HortScience horts 53, 11; 10.21273/HORTSCI13173-18