Might want to use DLI as your metric here, rather than PPFD. Much better integral of the total light energy you are delivering to your near harvest plant.
My thinking on this: as the number of hours of daylight wane, the intensity of the Autumn sunshine also decreases. Celestial Geometry, right?
So the plant gets the signal that winter is coming, seed making is prioritized and the natural process is for less light and water. Plant dries, seeds dry and fall to the ground. Natch!
-Grouchy
Grouchy, this my friend makes total sense to me – to use DLI as the proper target. I’ll figure it out. Thank you!!
This is true, I posted a paper here somewhere.
I think it is here.
I found this too.
Research performed in high-THC cannabis has shown that late and mild water stress can increase THC levels (Caplan et al., 2019). It is hypothesized that secondary metabolites are produced as a defense mechanism against stresses such as herbivory attacks (Jackson et al., 2021).
Now I don’t mean to overwhelm you but there are things to consider like midday depression.
Plants are exposed to high light intensity, high leaf temperatures and high air-to-leaf water vapor pressure deficit (ALVPD) during the day . These environmental stresses cause stomatal closure and photoinhibitory damage, leading to midday depression of photosynthesis.