Quote Originally Posted by oldmac
This subject seems to come up every few months, so let's get at it; :beatdeadhorse:
Sorry 'Wonder, plants don't need darkness to work on root developement. "Roots grow in the dark, but not when it is dark". In fact most "experts" reccomend 24/0, low level blue dominate light to root cuttings. If a plant needed a dark period to "work on root developement" you would not be able to produce clones with this method.
Just because you can, dosen't mean it's best to do so. Regardless...you're comparing apples to oranges. An unrooted clone is not following the same path, and has different needs, than a healthy seedling.
And again...If a clone performs 'better' under 24 hrs of light, this does not mean it's optimal for an otherwise healthy plant.
If it DOES perform 'better' under a 24/0 schedule, then what happens during the dark period that is disagreeable with an unrooted clone? In other words...if nothing changes at night, why is 24/0 better?

Normal darkness changes the plant phisiology, respiration and transpiration.
Relationship between transpiration and respiration in plants during the dark period
This changes the chemical, (nutrition) mineral, (cell building) and carbon ratios, (O2:CO2 exchange) and can determine proper photosynthesis, transpiration and cell integrity.

A Comparison of Dark Respiration between C3 and C4 Plants

Gonna have to provide some of your researtch info to convince me, OldMac. :thumbsup:

If you Google "plant processes during the dark period" you'll come up with other fine examples of the processes.