It is a proven fact that light rays break down THC. It is also a proven fact that most THC is produced during hours of darkness. When in periods of light plants allocate differing amounts of energy to different plant functions. Having limited energy to perform all the daylight functions certain functions receive lesser amounts of energy than others. THC production and growth are two that receive less energy than many others. During hours of darkness the stored energy is allocated so the highest priority functions receive the most energy and growth and THC production then receive greater amounts of energy, others are greatly slowed down or stopped.
Plants will not die the moment they go beyond 12 hours of darkness so if left in darkness they will continue to perform their normal functions for periods of darkness. That means continued increased amounts of energy for THC production.
When you combine increased levels of THC production without the daily loss of THC as it degrades as it performs one of its plant functions, working as ‘sunscreen’ for the delicate inner workings of trichome heads, the result is an increase over what would or even could be accumulated in the same period of time if left in a normal light schedule or just harvested. When you add THC without the normal daily loss of THC through light degradation THC levels will increase over that of what they would be or could be if light were allowed to degrade THC during the same period of time.
It is how plants work. If not why has it been common knowledge for ages to harvest plants by first light or to switch off lights after the last light cycle before harvest so light does not strike the plants before someone can harvest it resulting in lost/degraded THC? It is because THC levels are their highest at that point. Adding hours of darkness will increase that to some degree depending on the strain.
Research has shown THC levels do increase and it has also shown that it is does not occur equally in all strains, but if someone just waited 8 to 12 or more weeks while flowering what would be so absurd in waiting an additional 72-hours if an increase in levels of THC can be as great as 30%?
When it comes to the test results I have posted I would have preferred that both test groups were left to grow the same period of time rather than one harvested and one given 72- hours more of darkness before harvesting because that would tell the difference in a way that would be more acceptable to some.
What would have been best is if there had been three test groups where one was harvested and one allowed to grow another 72-hours in a normal light schedule and one given 72-hours of darkness. That would give a baseline, the group harvested, and then the difference in the other two groups would show the difference between the two different test groups left in light or darkness and the baseline.
Had that been done the results may have been the test group left in darkness that had up to a 30% increase over the harvested group might possibly been something like a 12% or 18% or 23% increase in THC levels in the test group left in darkness over the test group left in a normal light cycle rather than up to a 30% increase.
It is impossible to speculate with any acceptable degree of accuracy what amount of increase might have been found had the testing been done in that manner, just as no one can look at their plants and simply decide if there is or is not an increase. It cannot be proven or disproved by someone posting pictures and saying 'see,' it happened' or 'see, it did not happen.' While a picture will say a thousand words not so much as one single one of them will be backed by scientific fact so pictures are proof of nothing whatsoever. The human eye cannot see levels of THC while looking at pictures or plants in person.
Unfortunately the best we have to go on right now could be better but it does show a significant increase in THC levels can occur and even if it would actually be a lower percentage of increase compared to another test group left to live an additional 72-hours in a normal light cycle isn’t any increased level of THC worth finishing plants in 72-hours of darkness?
People use MH lights with HPS lights or add other forms of lighting with increased UV light to increase resin production in the quest for more potency so why would anyone not do something as simple as turning off their light(s) and waiting 72-hours before harvesting?
Virtually nothing will be lost, but there could be a significant gain depending on the strain. Considering all the absurd things people do to their plants in a quest to increase potency it makes no sense to not take advantage of what 72-hours of darkness before harvesting does for plants.