That is one of the common misconceptions about cannabis. Some plants need a dark period and some plants don't. Like Sunakard mentioned, cannabis is one that doesn't need a dark period--there is no benefit to a dark period when in veg. Running 18/6 encourages the plant to stretch (looking for light) during the dark period, 24/7 light and the plant will grow--develop new internodes rather than stretch.
THG you are correct marijuana is a C3
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.
So this is what they say???? but many factors again play a huge roll i have kept plants on 24 light cycle and did not see a significant or like they mention 33 percent faster ??? we all for for this being MJ is a C3 plant it will grow with 24 hrs of lighting..
Plants use periods of darkness, too. During dark periods, plants continue to take in oxygen and give off carbon dioxide in a process called respiration. During this time, the plant uses some of the energy that was stored as sugars during photosynthesis, producing proteins, hormones and other complex products. Therefore, lighting mature plants more than seventeen and a half hours per day will not increase production significantly, since photosynthesis will slow down after a certain number of hours Anyways if you figure costs of running lights 24 hrs and gains i bet it costed you more and you got less so was it really worth it
IMO darkness is needed to allow proper respiration and osmosis even in nature and folks we try to make our room a close to mother nature as possible we do not get 24 hrs of lighting except at the poles where nothing really grows ??? and only for a few months out of the year ????
even on your average day the clouds block sunlight