Observations, although I'm using top-down fluorescent lighting angled at 45%
A light spectrum in the scope of 400 to 700nm induces growth and development, and UV (100–400nm) and infrared (700–800nm) light play a role in plant morphogenesis—which is essentially the process of plants developing their physical form and external structure.
Optimizing Your Knowledge in the Grow Room
To maximize your yield, always aim for 40 moles, or 40,000,000 μmol, per day. Here is how much PPFD is needed per second for each phase of cannabis growth to achieve the DLI of 40 moles of light per day.
Seedling phase (18hr cycle): 200–300 μmol m-2 s-1
Vegetative phase (18hr cycle): 617 μmol m-2 s-1
Flowering phase (12hr cycle): 925 μmol m-2 s-1, (1500 μmol m-2 s-1 @2000ppm co2) (ballpark)
When choosing grow lights for cannabis, it is essential to check the technical specifications to determine if they are strong enough to get the job done. Of course, this doesn't mean that you have to buy the most expensive lights there are.
Still, it does mean that you should research each of these specifications in relation to your cannabis plants to find a grow light that will fully serve your needs. This is especially true with PPFD, as this is arguably the most insightful value for growers—it tells you exactly how much useful light your plants are absorbing at a certain distance from the grow light. With my fixed light source, as the plant develop height through stages, it will naturaslly grow into higher μmol ranges naturally dictated by its height. Look forward to filling the tent for the next grow.
Last week will see increased blues.
ELONGATED HYPOCOTYL5 (HY5), a bZIP-type transcription factor, acts as a master regulator that regulates various physiological and biological processes in plants such as photomorphogenesis, root growth, flavonoid biosynthesis and accumulation, nutrient acquisition, and response to abiotic stresses. HY5 is evolutionally conserved in function among various plant species. HY5 acts as a master regulator of a light-mediated transcriptional regulatory hub that directly or indirectly controls the transcription of approximately one-third of genes at the whole genome level. The transcription, protein abundance, and activity of HY5 are tightly modulated by a variety of factors through distinct regulatory mechanisms. This review primarily summarizes recent advances in HY5-mediated molecular and physiological processes and regulatory mechanisms on HY5 in the model plant Arabidopsis as well as in crops. Plants utilize light as the predominant energy source for photosynthesis. Besides, light signal acts as an essential external factor that mediates a variety of physiological and developmental processes in plants. Plants are continuously exposed to dynamically changing light signals due to the daily and seasonal alternation in natural conditions. The various light signals are perceived by at least five classes of wavelength-specific photoreceptors including phytochromes (phyA-phyE), cryptochromes (CRY1 and CRY2), phototropin (PHOT1 and PHOT2), F-box containing flavin binding proteins (ZTL, FKF1, and (LKP2), and UV-B RESISTANCE LOCUS 8 (UVR8). These photoreceptors are biologically activated by various light signals, subsequently initiating a large scale of transcriptional reprogramming at the whole genome level. Extensive genetic and biochemical studies have established that the ELONGATED HYPOCOTYL5 (HY5), a bZIP-type transcription factor, tightly controls the light-regulated transcriptional alternation. Loss of HY5 function mutant seedlings display drastically elongated hypocotyls in various light conditions, suggesting that HY5 acts downstream of multiple photoreceptors in promoting photomorphogenesis in plants. In addition to inhibiting hypocotyl growth, HY5 regulates other various physiological and developmental processes including root growth, pigment biosynthesis and accumulation, responses to various hormonal signals, and low and high temperatures. This review summarizes the recent advances and progress in HY5-regulated cellular, physiological, and developmental processes in various plant species. We also highlighted emerging insights regarding the HY5-mediated integration of multiple developmental, external, and internal signaling inputs in the regulation of plant growth.
Among the genes regulated by the circadian clock, we found that the excision repair protein XPA is controlled by the biological clock, and we, therefore, asked whether the entire nucleotide excision repair oscillates with daily periodicity. XPA transcription and protein levels are at a maximum at around 5 pm and at a minimum at around 5 am. Importantly, the entire excision repair activity shows the same pattern. This led to the prediction that mice would be more sensitive to UV light when exposed at 5 am (when repair is low), compared to 5 pm (when repair is high). We proceeded to test this prediction. We irradiated two groups of mice with UV at 5 am and 5 pm, respectively, and found that the group irradiated at 5 am exhibited a 4–5 fold higher incidence of invasive skin carcinoma than the group irradiated at 5 pm. Currently, we are investigating whether this rhythmicity of excision repair exists in humans.
Molecular mechanism of the mammalian circadian clock. CLOCK and BMAL1 are transcriptional activators, which form a CLOCK-BMAL1 heterodimer that binds to the E-box sequence (CACGTG) in the promoters of Cry and Per genes to activate their transcription. CRY and PER are transcriptional repressors, and after an appropriate time delay following protein synthesis and nuclear entry, they inhibit their own transcription, thus causing the rise and fall of CRY and PER levels with circa 24-hour periodicity (core clock). The core clock proteins also act on other genes that have E-boxes in their regulatory regions. As a consequence, about 30% of all genes are clock-controlled genes (CCG) in a given tissue and hence exhibit daily rhythmicity. Among these genes, the Xpa gene, which is essential for nucleotide excision repair, is also controlled by the clock.
Circadian control of excision repair and photocarcinogenesis in mice. The core circadian clock machinery controls the rhythmic expression of XPA, such that XPA RNA and protein levels are at a minimum at 5 am and at a maximum at 5 pm. The entire excision repair system, therefore, exhibits the same type of daily periodicity. As a consequence, when mice are irradiated with UVB at 5 am they develop invasive skin carcinoma at about 5-fold higher frequency compared to mice irradiated at 5 pm when repair is at its maximum. The mouse in the picture belongs to the 5 am group with multiple invasive skin carcinomas at the conclusion of the experiment.
If you are interested in the plant's circadian clock, then check out Far-Red photons:
"The R:FR ratio of direct sunlight is about 1[.]5 during most of the day, but it approaches 0[.]6 or so during twilight when the atmosphere preferentially scatters blue light and the sky turns yellow and red. This only lasts for half an hour or less, but it is important because plants use these changes to synchronize their internal circadian clocks both with the24 hour day and the seasons. This involves a burst of gene expression activity that is controlled by phytochrome.”
“Far-Red Lighting and the Phytochromes”, Ian Ashdown, Maximum Yield, maximumyield․com/far-red-lighting-and-the-phytochromes/2/17443
@Ultraviolet, Sometimes I forgot to plan out the best photoperiod schedule and suddenly find myself dramatically shifting the timer once flowering begins. I wonder if hitting them with sunrise/sunset R:FR would alleviate any circadian confusion.
@Natrona, this was my 2 year old dragon willow bonsai, I placed it outside a few weeks back on a sunny day, forgot and it got smoked in a snow storm, thought I'd lost it. Plonked in a copper rod and she came back to life, frankentree.
@Metatronix, Well that's optimistic :)! Every little helps. I found with such a big pot it would allow for unrestricted growth of rootzone, but the water was sitting deep in medium and with the pot taking up so much space it was very hard to keep the medium warm & with very little air getting to where the roots needed it. Prime breeding ground for some bacteria & fungi.
Always been fond of the idea of automating a grow tent for the entire grow, start to finish, the challenge with auto watering was over-watering, this could also dry the medium enough within a timeframe to prevent the conditions for the bacteria n fungi in the first place.
Originally had some ideas for regular-size pots with airstones but then I got stoned and bought a 100-gallon fabric and here we are.
@Ultraviolet, I 💚 the idea ...it really could increase the yields IMO. It would revolutionize the flowerpot industry kind like the Autopot but for soil.