8 Hours Light Please! ..says Lab Report

Effect of Prolonged Photoperiod on Light-Dependent Photosynthetic Reactions in Cannabis


@Storm Crow posted this but was soon lost ..after one hell of a search I've reposted this here, more for my sake really but once deciphered holds a ton of info for us, the worst is 'we' are growing it wrong, as our babes now,
it seems require 8 hours of DARK per 24 hours This I've been struggling with since its release



Abstract
Industrial hemp is a fast-growing, short-day plant, characterized by high biomass yields and low demands for cultivation.
To manipulate growth, hemp is usually cultivated under prolonged photoperiods or continuous light that could cause photooxidative damage and adjustments of photosynthetic reactions. To determine the extent of changes in photosynthetic response caused by prolonged light exposure, we employed chlorophyll a fluorescence measurements accompanied with level of lipid peroxidation (TBARS) and FT-IR spectroscopy on two Cannabis cultivars. Plants were grown under white (W) and purple (P) light at different photoperiods (16/8, 20/4, and 24/0).
Our results showed diverse photosynthetic reactions induced by the different light type and by the duration of light exposure in two cultivars. The most beneficial condition was the 16/8 photoperiod, regardless of the light type since it brought the most efficient physiological response and the lowest TBARS contents suggesting the lowest level of thylakoid membrane damage. These findings indicate that different efficient adaptation strategies were employed based on the type of light and the duration of photoperiod. White light, at both photoperiods, caused higher dissipation of excess light causing reduced pressure on PSI.

Efficient dissipation of excess energy and formation of cyclic electron transport around PSI suggests that P20/4 initiated an efficient repair system. The P24/0 maintained functional electron transport between two photosystems suggesting a positive effect on the photosynthetic reaction despite the damage to thylakoid membranes

.....blah blah, 19 pages later of some very deep shit:

Conclusions
Conclusions Based on the results obtained from this investigation, it can be concluded that different photoperiods and different types of light provoked adverse responses of two Cannabis cultivars. The 16/8 cultivation under white light was proven to create the most beneficial conditions for efficient physiological response corroborated with the highest PItotal in both cultivars.
Although the 16/8 cultivation under purple light revealed lower PItotal values compared to those measured under white light, both types of light showed lowest TBARS contents suggesting the lowest level of thylakoid membrane damage. After exposure to a prolonged photoperiod (20/4) and continuous light (24/0), cultivation under white light (W) induced similar responses in both cultivars. White light, at both photoperiods, caused inactivation of certain parts of RCs causing lower ability for regulation of absorbed energy and its utilization by photosynthetic membranes.
However, higher dissipation of excess light (DI0/RC) reduced the pressure on PSI which caused reduced capacity for photochemical QA reduction and consequently caused a slower transfer of electrons to the PSI acceptor side (negative G-band). Therefore, exposure to white light most probably increased the number of available NADPH+ molecules which served as an advantageous compensatory mechanism. Purple light, however, provoked somewhat different responses depending on the duration of exposure to light.
Although the 20/4 cultivation caused inactivation of OEC and revealed a poor ability for regulation of absorbed energy and its utilization, alternative electron donors maintained the electron feed from the OEC to the RCs. In addition, efficient dissipation of excess energy and formation of cyclic electron transport around PSI suggested that purple light initiated competent photoprotective strategies and promoted the efficient repair system (lower TBARS level).
Cultivation under continuous purple light (P24/0) retained the functional electron transport between two the photosystems and increased dissipation ultimately maintained PItotal suggesting a positive effect on the photosynthetic reaction even though damage to thylakoid membranes occurred. Additional analyses of antioxidant activity and antioxidant response are needed to elucidate the detailed physiological profiles of two Cannabis cultivars due to prolonged light exposure and type of light

Here: .pdf: Effect of Prolonged Photoperiod on Light-Dependent Photosynthetic Reactions in Cannabis

 

I can't remember if my uncle's, a hemp farmer even flipped to flower, or the external equalivent., by growing hemp very crowded like, they find it very difficult to flower ..(he did Pidgeon racing and made friends in the west, that led to me being in the west ..lol