The Inheritance of Chemical Phenotype in
Cannabis sativa L.
http://www.genetics.org/content/163/1/335.full.pdf
this reminded me of your post when I was looking for other information
That's a great article. It claims cbd-thc ratios are dependent on codominance, and usually come in 3 models: all cbd, a 1:1 mix, or all thc. That's interesting because some strains test in at, say, CBD 2% thc 8% (though most Ive seen are roughly 1:1 if they have any cbd at all).
Id like to run some theories by you guys and see if any bounce off the right way. To explain the ratios which wander off the 1:1 marker one would expect from a purely codominant inheritance pattern, could the anomalous ratios be due to the time at which the crop was harvested, the intensity of the lighting, and the curing process?
There are potent strains of high THC weed everywhere these days, but there are also many that have medium or low THC. However, the vast majority have a ratio of 1:0 THC:CBD. Does anyone know if the genotype for high overall resin production (regardless of whether its THC or CBD in that resin) is independent of the genotype for ratio? That is, will a dank plant mixed with a weak plant make half weak offspring and half dank? Or would their resin production be a mix, somewhere in between the parents?
If it IS independent then in order to make a 20% CBD 0% THC strain, my hypothesis is, mixing a strain of 1:1 low yield with a high yield 1:0 THC:CBD, half the offspring would have high yield THC and CBD, and half low. So
the mother, 1:1, passes on both genotypes (CBD and THC) and the gene for low or moderate resin production; the father, 1:0, passes on the genotype for only THC, but also has the chance to pass on the genotype for high resin production. Half the offspring would get the gene for high production, half for low or moderate, depending on from which parent they derived the genes for that train. Independently from this allele, half the offspring would get the codominant phenotype of 1:1 ratio, and half would get the codominant phenotype for 1:0 (though one of the genes would be missing, the cbd gene, so only thc would be produced). So at this point, the half of the plants that dont have the desired 1:1 ratio would be rejected from the gene pool, and the half that have low yield would be too. What would be left to breed in this generation would be all high yield plants, half of which would be 1:1 and half 1:0. One more generation would be needed to take the ¼ of the offspring that would inherit the 1:0 CBD:THC (not to be confused with 1:0 THC:CBD) and breed them together.
If the high yield 1:1s were bred together they should all be high yield, and follow the same 1:2:1 ratio pattern that hexthats link described. That would mean a stable, high yield CBD strain should be only 4 generations away for the average breeder! Would it not? Thats less than a year away from THC-less weed for all!
