'Value* for hrectfetE (ages approximate I TSw text for discunmn of sampling tsehniquaB
SOURCE: P.S. F*ltitrman at at.. "Mississippi Grown Cannabis iativa L.," Journt! of fnarmxputicai Science SO f1971h 1246: C-£, TurrWF •(•)., "Constituents of Canna-bistttiv* L. X.."Act* PftormaCtutic* Jafftrstaricn 25 (19751: 7; H. Kaneshirna et ?!..
"Studies on Cannabii in Hokkaido, Pert 6," HpklftifforitSU Eisti Ktatfytithoko 23 H973J: 1.
Cannabinoid Phenotypes
There are two basic types of marijuana plants: those cultivated for their fiber content and those cultivated for their drug con-tent. The fiber type is generally grown in temperate climates and is useful for making cloth, rope and paper. It yields little or no drug. The drug type is generally grown in warmer, drier coun-tries and is less useful for fiber. The fiber type has usually been called Cannabis sativa, and the drug type Cannabis indict Dis-tinct groups within a species which differ in their form, chemical content and behavior are known, as phenotypes (literally, visible types). Genotype, on the other hand, refers to the genes or
hereditary makeup of an organism. The phenotypic differ-ences which exist in various strains or stocks of marijuana with respect to their content are the result of different genes interacting with environmental variables. In order to enhance marijuana potency, we can manipulate growth conditions as well as exercise
considerable care in the selection of seeds.
In the last century, breeding programs have led to the de-velopment of several hundred distinct varieties. Virtually all of these have been selected for the fiber content of their stems or the oil content of their seeds, wirh little emphasis on their drug content. However, recently there has been considerable research on determining the relative amounts of cannabinoids in various types of marijuana and delineating possible phenotypes with re-spect to their THC and CBD content. The results so far indicate that plants from temperate climates tend to have a high CBD
46 THC AND CBO CONTENT
and low THC content, while those from warm southern
tend to have low CBD and high THC content. Four phe no types have been described, and a fifth is proposed here:
Type I High THC and low CBD in both males and females;
matures slowly; is usually native to areas below latitude 30* North (which runs through Morocco, Iran, N, India, S, China, N. Mexico and Florida),
Type II Moderate levels of CBD and THC with higher CBD, and females having more of both; usually matures rapidly;
native to regions north of latitude 30° North,
Type III Moderate to high levels of CBD with low levels of THC, and females having more of both; usually matures rapidly; native to regions north of latitude 30° North, Type IV High THC and low CBD in both males and females;
matures slowly; native to northeastern Asia (Japan, Korea, N, China). Has small quantities of cannabigerol monomethyl ether (an inactive cannabinoid). Plants of ten Very tall.
Type V High THC and very low CBD in both males and fe-males; matures slowly; native to Indonesia, Southern Africa, and Nepal. Up to 80% of the THC is actually THCV (tetrahydrocannivarinj with a propyl side chain replacing the amyl side chain of THC.
These phenotypes appear co have a solid genetic basis since, as the data in the tables will show, seeds from these types produce essentially the same kind of marijuana no matter where they are grown. The slow maturing, high THC types are adapted for conditions near the equator where longer growing seasons allow thetn to develop fully. A great deal of variation exists and there is much overlap, particularly between types II and III, It is possible that the phenotypes were much more distinct in the past when transport of seeds from every area of the world was limited, Hybrids between the types seem to be completely fertile and to contain cannabinoids approximately intermediate between those of the parents, though the offspring may often deviate to either the high or low THC parent. It would be
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4fl THC AND CBD CONTENT
ly interesting to follow the THC content of n high THC southern strain raised in the north through several inbred generations to determine whether, if it is protected against cross fertilization by the native low THC strains, it can maintain its high THC output.
There is, however, the continual problem of natural selection.
All marijuana seeds, including those of inbred strains, vary considerably, Furthermore, the slower developing plants will have little, if any, mature seeds when it is time to harvest in the northern climates. Consequently, they will be undci represented (if at all) in the second generation. Sensitivity to the other factors which influence the percentage of seeds that germinate and rate of development of the seeds also varies in each strain of
marijuana. This means that even if die plants arc inbred and grown under carefully controlled conditions, the average genetic makeup of the population will probably change for each genera-tion. There seems to be only one well-controlled experiment on this point. High THC South African seeds were grown in tem-perate areas by some half-dozen growers and produced so little CBD that it was virtually un detectable, as well as significant amounts of propyl cannabinoids. A careful study in a phyto-tron [growth chamber) over three generations at a high and a low temperature showed no CBD and little variation in canna-binoid content. Content was always higher at lower temperatures.
However, by the third generation, natural selection had
eliminated the plants which had large amounts of propyl canna-binoids.
Some data exist for second or third generations from other studies such as the one at the University of Mississippi
previously referred to. However, in those studies there was little control over pollination, which means that the second generation Mexican seeds could be a cross between Mexican and Nepalese—
or any other males that happened to mature at the right time, within a hundred yards or so.2