Phytochrome Regulation in Plants
Plants monitor changes in day length with a bluish, light-sensitive protein pigment called phytochrome. Phytochrome exists in two forms, based on the wavelength of the light that it absorbs. It is generally produced in meristematic tissues in very minute amounts. The two stable forms can be converted to each other by absorbing light. Pred (Pr) which absorbs red light and Pfar-red (Pfr) which absorbs far-red light. In the daylight more Pr is converted to Pfr (the active form) than vice versa. Pfr will convert back to Pr over several hours in the dark where it would be stable indefinitely. The conversion in light is almost instantaneous. The phytochrome mechanism is what transforms the crook in the hypocotyls of the emerging seedling into a straight stalk. Stem elongation appears to be inhibited by Pfr. However, if light levels are low, the shaded stems of a tree for example, more far-red light will reach them and cause the conversion to Pr which lowers inhibition and allows the stems to grow longer and out from under the shade.
The interconversion abilities of phytochrome:
Cannabis is a short day plant (SDP), meaning flowering begins to take place when Pr (which is converted from Pfr in the absence of light) is present in higher concentrations than Pfr (when there is more than 12 uninterrupted hours of no light)
Thankfully, our lovely green friend belongs to a category of plants that do not
require a dark period (for different forms of metabolism) during the vegetative stage.
" One way in which plants are categorized is by the way they gather and handle carbon dioxide. Cannabis is a C3 plant. It uses the CO2 it gathers during the light period, when it is photosynthesizing. Plants designated C4 also gather CO2 during the dark period for use during the light period. Many C3 plants, including cannabis, do not need a rest period. They continue to photosynthesize as long as they are receiving light.
The plant's photosynthetic rate determines its growth rate because the sugars are used by the plant to build tissue and for energy. Cannabis under continuous light will grow 33% faster than the same plants on an 18-6 light regime."
This has been discussed in many of the "18/6 vs 24/0" threads on various forums. Have a search, its pretty interesting!
So....G.rower, as long as you are providing at least 12hrs of absolute darkness in every 24hr cycle(there
are advanced exceptions), your plants should finish their lifecycle as you expected.
As for this limpness that you have observed; it seems to indicate a lack of transpiration, meaning the stomata have closed and fluids are no longer passively passing through the plants' tissue, as others have stated already.
Maybe some research into the environmental factors that can stop/slow transpiration would be beneficial. But again, without pictures, or actually being there, it is too diffucult to give you the straightforward answer you are looking for
Good luck and stay strong
