This just came out and I thought it looked interesting. Seems that the number of hours of light can affect the potency in both THC and CBD strains. If you are growing CBD strains this may make quite a difference! I broke the abstract into more readable chunks, and the link leads to the full study. Moving Away from 12:12; the Effect of Different Photoperiods on Biomass Yield and Cannabinoids in Medicinal Cannabis Moving Away from 12:12; the Effect of Different Photoperiods on Biomass Yield and Cannabinoids in Medicinal Cannabis The standard practice to initiate flowering in medicinal cannabis involves reducing the photoperiod from a long-day period to an equal duration cycle of 12 h light (12L)/12 h dark (12D). This method reflects the short-day flowering dependence of many cannabis varieties but may not be optimal for all. We sought to identify the effect of nine different flowering photoperiod treatments on the biomass yield and cannabinoid concentration of three medicinal cannabis varieties. The first, “Cannatonic”, was a high cannabidiol (CBD)-accumulating line, whereas the other two, “Northern Lights” and “Hindu Kush”, were high Δ9-tetrahydrocannabinol (THC) accumulators. The nine treatments tested, following 18 days under 18 h light/6 h dark following cloning and propagation included a standard 12L:12D period, a shortened period of 10L:14D, and a lengthened period of 14L:10D. The other six treatments started in one of the aforementioned and then 28 days later (mid-way through flowering) were switched to one of the other treatments, thus causing either an increase of 2 or 4 h, or a decrease of 2 or 4 h. Measured parameters included the timing of reproductive development; the dry weight flower yield; and the % dry weight of the main target cannabinoids, CBD and THC, from which the total g cannabinoid per plant was calculated. Flower biomass yields were highest for all lines when treatments started with 14L:10D; however, in the two THC lines, a static 14L:10D photoperiod caused a significant decline in THC concentration. Conversely, in Cannatonic, all treatments starting with 14L:10D led to a significant increase in the CBD concentration, which led to a 50–100% increase in total CBD yield. The results show that the assumption that a 12L:12D photoperiod is optimal for all lines is incorrect as, in some lines, yields can be greatly increased by a lengthened light period during flowering. Granny
That's a very interesting study! The results suggest that the optimal flowering photoperiod may vary depending on the strain and the desired cannabinoid content. While a 12L:12D photoperiod is often considered the standard for inducing flowering in cannabis, the study found that a 14L:10D photoperiod at the start of flowering led to higher biomass yields for all three strains tested. However, the study also found that the effect of different photoperiod treatments on cannabinoid content varied depending on the strain. In the THC-dominant strains, a static 14L:10D photoperiod caused a significant decline in THC concentration, while in the high-CBD strain, all treatments starting with 14L:10D led to a significant increase in CBD concentration and total CBD yield. These results suggest that growers may want to experiment with different photoperiod treatments to optimize both yield and cannabinoid content for their specific strains. It's also worth noting that the study tested only three strains, so further research may be needed to determine whether these findings hold true for a wider range of cannabis varieties.
when they say flower biomass was larger how many % larger i guess i better click the link very interesting
Anecdotally, I noticed a slight potency increase going from 12 to 12.5 hours, which I run now for flower. Have looked for it but can never find it, but a couple years back read a crazy but great study of non-24 hour periods. They found that something like 20 or 21 hours of light, followed by 12 hours of dark, made the most difference. Does make sense, as cannabis is not a 'short day' plant, its a 'long night' plant, meaning that the hours of drak cause flowering instead of hours of light.
ok i read some of it the northern lights did well under 14 light almost 50% more biomass but the kush biomass went up and the THC dropped at the same rate i will stick to 12/12
Thanks for sharing this...It was an interesting read. My initial take away is this may align more with genetic strain variability via native growing conditions vs amount of total indoor light. In the study they say - Under natural field conditions, photoperiods progressively change with the seasons, whereas in controlled facilities, the changes are generally abrupt. Whether a progressively changing photoperiod, compared to a single sudden change, affects yield attributes in a glasshouse/indoor system remains to be determined. There was a study a few years back that took several strains and planted them in different locales....High on a mountain top....down on the plains, etc....The strains grown that originated in the mountains had higher cbd levels at elevation then when planted down on the plains. This lead the researcher to believe the origin environment had more of an impact on the plant via its genetics.
@B0st0nBoi I think this is the study you referred to- Influence of Altitude on Phytochemical Composition of Hemp Inflorescence: A Metabolomic Approach. (Italy) (full – 2020) Influence of Altitude on Phytochemical Composition of Hemp Inflorescence: A Metabolomic Approach And this one was also along those lines- Abnormal Meiosis in Tetraploid (4x) Cannabis sativa from Lahaul-spiti (Cold Desert High Altitude Himalayas)-A Neglected But Important Herb. (India) (full – 2016) https://www.eresearchco.com/article...t-higher-altitude-himalayasa-neglected-bu.pdf Granny
So leave the CBD plants at 14hrs and leave the THC plants at 12.5 hrs, halfway thru flower. Thnx granny
So leave the CBD plants at 14hrs and leave the THC plants at 12.5 hrs, halfway thru flower. Thnx granny