Do we "know" that yeah? Link to a study please?
There was a study that showed 72hours of darkness prior to harvest can increase THC levels on some strains, this was nothing to do with inducing stress.
Until there's so empirical evidence it's all hearsay/theory at best, total old school hippy bullshit at worst. I'd assume the latter...
There are some evidences mate, but what I think is since a good few coming from state funding, the outcomes benefiting the users are hard to find because of censorship and stuff. They only to give the negative side, like the carcinogens.
OK another example,
1:Leaf:
before you put your garden into flowering from 18 to 12 hours, give the plants 36 hours of darkness; by doing this it, will reset the plants natural body clock. After 36 hours (or anything between 24 and 40 hours) the plant will go straight into flowering rather than adjusting from 18 to 12 which in some strains can mean an extra few weeks. When the plant is finished give it another 36 hours, this will reset the body clock again this time the plant knows it is finished and will push out all remaining energy into its last trichome production try it.
This is a from an Interview with Adam of T. H. Seeds
And I have heard it as well.
And he is not some grower or breeder, he also has to keep up with the name of TH Seeds, so why would he say some hippy shit for others to believe.
An from what he does, isnt it
stressing?
2
Cannabinoid levels of individual mature glandular trichomes from two clones and two strains of Cannabis sativa L., which included both drug and fiber phenotypes, were investigated by gas-liquid chromatographic analyses Capitate-stalked glands were selectively harvested from vein and nonvein areas of pistillate bracts while capitate-sessile glands were harvested from these areas of leaves The qualitative cannabinoid profile characteristic of the strain or clone was maintained in the individual capitate-stalked glands while the quantitative cannabinoid profiles varied with each strain or clone and between vein and nonvein areas as well Capitate-sessile glands were found to contain conspicuously lower levels of cannabinoids than capitate-stalked glands This study emphasizes that glands of Cannabis represent a dynamic system within the cannabinoid synthesizing activities of this plant.
American Journal of Botany
© 1978 Botanical Society of America
http://www.jstor.org/pss/2442328
The reason I gave them source is to show how changes have been bought to the plant.
For example the second study shows that how glandular areas and pistillate brands have cannabinoid levels and its variance among other parts of the plant, if this was told a century back, doubt many would believe it coz of the lack of advanced science.
Its all a part of learning end of the day, its all about chilling on the journey!