Astir Grow Led Panel Project...

repuk said:

music64, yes, yo should wire the AC wires in parallel (join neutral with neutral and live with live). Beware You cannot join the wires going to the LEDs!!!

tenthirty, drilling and tapping? ouch... I thought on using thermal glue...

Click to expand...

stardustsailor said:

Well,for starters C3 plants have more ChB in general...
ChA is a more 'tropical' photosynthetic pigment....
(Only, Equatorial areas have plenty of 650-680 nm in sunlight...Greater angle of sun..Less red photons absorbed by water in atmosphere)..
660 nm light in C3 plants ,mainly alter the phytochrome state from the "base " Pr to "active" Pfr...
Lots of Pfr.....
I have performed quite a bit of real-life experiments with 660nm leds....
Cactii seem to like it...
C3 plants ,no...In fact,not at all...
They adapt their leaves to "extreme sunlight conditions"..
Few ,small(reduced lamina surface area) and thick leaves is what you get with 660 nm reds...
Abnormal stem/petiole growth..Extensive internodal streching...
Closed stomata..Reduced respiration/transpiration..And reduced CO[SUB]2[/SUB] intake...
(You need elevated CO2 concentration in atm. )
Lower Photosynthetic Saturation Point (easy to get "CO[SUB]2[/SUB] limited " )
Increased photo-oxidation and photoinhibition
Long and flimsy buds....
And a reproductive state ,that lasts.... forever...
Difficult for flowers to reach maturity.If at all....
Do all these ring a bell ?
Tip:.....Tropical Sativas....
...
...
I believe that Warm White leds carry all the orange,red and NIR (far red ) a plant needs...With a nice 'nature-like' spectral curve...
And Warm Whites ,do not emit so much at blue region...
Way better than any actinic red...With higher efficiency and stability...
I just 'top' the 620-640 region with only a few reds....
And it seems that the whole concept is working ,better than,of what was expected....
...
...
Why cheap leds ?
1) They do the job.With a small difference( in power -25% max.) in comparison with high-quality leds.
The big difference is their price..(-1000% min.)
2) All leds, are subject to constant development.
Why pay a s..load of money on leds ,that next year will be 'old history' ?
Better ,save the money ,buy the new ones and constantly keep the panel upgraded ,to the latest tech...
3)They do not need reflow oven to be soldered.Easy to service/change.
Why cheap CC driver ?
-If it gets fried ,it is very cheap to buy a new one...
It's just a power supply.
Not a sophisticated,mono-block, high-end sound amplifier....
No need to be an expensive piece of electronics...
Why cheap PCB ?
Because they do the job just fine....
A plain 'sandwich' of thin aluminium plate,less than 100 microns epoxy insulation layer and copper 'lines'..What more to ask ?
And...
The heatsink stays there...For the full service life of panel(s)....
Never to be changed.
But its role,probably,is the most crucial one...
High quality leds with bad cooling or mediocre leds with ideal cooling ?
Which one works best,you think ?

Moreover....It's is not just 'parts' quality...
There are many other things to take under consideration such as overall efficiency,serviceability,ability of upgrading,retail price,ect....
Which add up to overall quality...
...
...
There is not such thing as 'penetration'....
Light is not a bullet.
"Penetration" stands ONLY for green/yellow light.That's the only wavelength that 'penetrates' a leaf.All other wls are absorbed by photosystems.
Moreover ,even if the statement "penetration" was true,it would have had a meaning for a single-point light source.Like HIDs for example.
These panels are designed to be placed ,wherever canopy needs illumination.
They are not a single-point light source.
A number of them,placed accordingly to canopy,work as 'one' surrounding light source.
Thus,penetration,even if it was standing true,has no meaning,since there is not a dark spot/area,with multiple light sources...
No matter of phenotypes,lateral or vertical growth..
...
...
1 Watt leds ,apart from being the most efficient,they produce small amounts of heat...
Easier to keep cool ,than 3,5,10,ect Watt leds...
...
...
Very good questions,BTW...

Click to expand...

newworldicon said:

So are you saying that sativa dominant strains will grow better under most LED panels considering they have mostly 660nm reds in them?

What do you think of this spectrum and what sort of strain would you think suits it best, I have pondered this question for some time..

Parts numbers and data sheets:
Helixeon Red HMHP-E3LR: 630-640nm bin: V0 (top bin)
Helixeon Hyper Red HBHP-E3LR: 640-650nm, 650-660nm, 660nm-670nm bin: Q0 (top bin)
Helixeon White HMHP-E3HW: 6500k bin: Y0 (top bin)
Helixeon Farred 720-740nm bin: n/a

Ratio: White:red:farred 5:9:1

Click to expand...

tenthirty said:

What are the white spots on the leaves? PM?

Click to expand...

The relevance of green light responses is predicated on the assumption that there are contexts where a plant may encounter enriched green conditions. Such states abound in the natural environment. Under the cover of leaves plants experience a pronounced contrast from unfiltered solar illumination. Primarily, there is a decrease in radiant flux and a shift in the ratio of visible wavelengths to far-red light (Fig. 1). The understorey of a canopy is rich in far-red light as blue and red light have been removed by overhanging foliage. This depletion shifts the ratio of blue and/or red light to green light, as green light is readily reflected from and transmitted through plant tissues. Green light is efficiently transmitted through the plant body, playing more of a role in photosynthesis than red or blue in some contexts (Sun et al., 1998), suggesting green light may prove useful as a signal to tissues not directly exposed to the light environment. Potential green light effects may also vary with developmental context. An etiolated seedling emerging through the soil has negligible chlorophyll, and green light is just as penetrant as blue, red, and far-red light. It is naïve to think that nature would not identify and capitalize on the information present in these prevalent environmental conditions.

Click to expand...

Enter heliochrome

USDA scientist Takuma Tanada studied photobiological responses in plants. Data from many of his studies pointed to the existence of a far-red/green reversible receptor acting complementary to phytochrome termed ‘heliochrome’ (Tanada, 1997). The evidence for heliochrome arose from studies where responses induced by far-red light (≥710 nm) were completely negated by the application of comparatively small amounts of green light (550 nm). Red light (660 nm) was completely ineffective in negating the far-red responses, demonstrating that the observed effects were not due to Borthwickian red/far-red reversible phytochrome activity.
In one study red, far-red, and green relationships were tested by monitoring the closing of Albizzia julibrissin pinnules (Tanada, 1982). Albizzia pinnules exhibit nyctinastic closure, and closing can be delayed by far-red light of 710–730 nm. The delay induced by far-red light at substantial fluence rates (18–43 μmol m[SUP]−2[/SUP] s[SUP]−1[/SUP]) could be completely negated by co-illumination with dim green light (0.01–5 μmol m[SUP]−2[/SUP] s[SUP]−1[/SUP]). Green treatment alone had no effect, yet alternating different combinations of red, far-red, and green pulses showed that green and far-red could toggle the response. Most importantly, red light at 660 nm had no effect, indicating that the observed responses were not classical phytochrome effects (Tanada, 1982). Later, the phenomenon was tested using bright flashes of light. Here, blue light (450 nm) could delay closing, similar to far-red light (Tanada, 1984b) and green light could completely negate the blue light effect. Tanada concluded that the far-red absorption state of heliochrome must also be blue sensitive.
Similar results were reported in studies in Brassica campestris, where a far-red day extension induced prolific flowering (Tanada, 1984a). Co-irradiations with increasing fluence rates of red light could not reverse the far-red induction. Rather, minor illumination with green light caused a fluence-rate-dependent decrease in the number of plants committing to floral habits. The author also shows that inductive day extensions from a 710 nm pulse could be completely negated with a 550 nm pulse, and that the 550 nm inhibition could be reversed with a 710 nm flash. As in previous studies (Tanada, 1982), 710 nm light was more effective than 730 nm (the peak of Pfr absorbance) and 750 nm had no effect.
Tanada is probably best recognized for the ‘Tanada effect’, a discovery made while rinsing experimental glassware. Some excised oat and mung bean root tips used in experiments would adhere to beakers, others would not. Binding was shown to be rapid (occurring within 30 s), and red and far-red reversible, indicating phytochrome response (Tanada, 1968). These observations were consistent with the hypothesis that phytochrome induced ionic changes as primary steps in the signalling process. This effect was later revisited in soybean experiments by measuring light-induced changes in potential using an electrometer (Tanada, 1983). As seen in earlier experiments red/far-red (660/760 nm) reversibility of potential changes indicated a clear role of phytochrome. However, irradiation with 710 nm light led to changes similar to those induced by 660 nm. This induction could be completely negated with a subsequent pulse of green light, but could not be reversed by red light. Interpretation of these data is problematic because blue light was not tested, nor were green effects tested extensively. However, this study presented evidence that green light could negate an effect of a far-red treatment that was uncoupled from phytochrome activity. Its far-red nature argues against a cryptochrome component, as the redox states of cry chromophores have negligible absorption in the far-red.
The data supporting the heliochrome hypothesis could be explained with today's understanding of plant photosensing if two assumptions are made. First, the effects are cryptochrome driven and reversed by green light acting via the neutral semiquinone chromophore. Also, far-red effects would have to be imparted through phyA and parallel the blue effects, much like phyA and cry2 together promote CONSTANS stability leading to flowering (Valverde et al., 2004). However, far-red/green effects are difficult to reconcile unless the green form of cryptochrome overrides or causes degradation of phyA. These are cumbersome models to test, but remain the only way to resolve these data, as the original work was always careful yet unknowingly incomplete.
When considered together, the far-red/green reversibility of pinnule closing, flowering, and ionic results are perplexing. The experiments were performed in sensitive systems, measuring the effects of finite treatments over short time-courses. Dose–response relationships were often demonstrated and the physiological responses observed were not ambiguous. In 1997 Tanada proposed that heliochrome was a haem-based receptor, and today this possibility could be tested using haem oxygenase mutants. Even with the benefit of hindsight, Tanada's work presents another interesting case where green light exerts specific effects on plant responses that are not easily explainable without invoking complex interactions of dichromatic states within known sensors or some effect of a novel receptor.

Click to expand...

Green light effects on leaf growth and stomatal conductance

The effects of green light on stomatal opening noted by Zeiger's group were extended to whole plants by NASA scientists. Plant growth in artificial environments remains a key provision to long-term space colonization. Therefore NASA scientists have explored the effects of combinatorial light conditions on plants. Many of these studies simply focused on the effects of narrow-bandwidth red and blue sources compared to conventional sources (Brown et al., 1995; Goins et al., 1997; Yorio et al., 2001). One central concern emerged when plants were grown under some light conditions. Plants grown under red and blue LEDs appeared black or purple rendering it difficult to monitor plant growth and health in the artificial state. Also, miscoloured plants are not as visually appealing to a potential crew (Kim et al., 2004a).
With the goal of making plants appear green NASA scientists assessed the effects of green light supplementation to a red and blue background, and discovered that addition of this allegedly benign light quality generated conspicuous effects. These experiments differed from those performed by Went and Klein in that these kept PPF constant and varied the proportion of green light added. This approach has the advantage of keeping metabolism static, yet the disadvantage of skewing activation of photosensory networks that contribute to developmental responses. These studies also use different species and developmental states relative to earlier studies. For this reason the results need to be considered independently of the previously described work.
In these reports the effects of combinatorial red, blue, and green (RB+G) light treatments on leaf growth and stomatal conductance in lettuce were compared to red and blue (RB) alone (Kim et al., 2004a, b). Green light supplied by green fluorescent lamps was added to a background of red and blue LED light. There was very little (if any) far-red light which is important for discounting potential phytochrome interpretations. The authors discovered that lettuce plants grown in RB+G treatments displayed leaves with larger specific leaf area and less thickness compared with RB alone (Kim et al., 2004a). Also, plants grown under RB treatments demonstrated higher stomatal conductance when compared with those under RB+G, with the lowest stomatal conductance reported in plants grown under green fluorescent lamps alone (Kim et al., 2004b). In addition, while stomatal conductance was greater in cool white fluorescent treatments than in RB+G, the dry mass of the plants was greater in RB+G implying the weaker stomatal conductance did not negatively affect carbon assimilation (Kim et al., 2004b). Plant dry mass was greatest under RB+G treatments (where 24% of the spectrum was broadband green light) when compared with RB, the opposite of the effects noted by Went (1957; Fig. 2). However, these results do agree with previous findings that plants grown in RB+G treatments displayed larger specific leaf areas than those grown under RB treatments (Kim et al., 2004a). These experiments demonstrate that supplemental green affects plant physiology in conditions where red and blue systems are saturated. It remains to be seen if these effects are cry-dependent or cry-independent, as they were performed in species where photoreceptor mutants are not yet available.

Click to expand...

Conclusions

Recent findings of cry-dependent and cry-independent green photoresponses suggest that green, in addition to red, far-red, blue, and UV sensory mechanisms, monitor and adjust plant growth and development. For the most part, the recent findings mesh well with central themes from older studies performed before the advent of molecular-genetic tools and modern techniques. One theme presented throughout this review is that the effects of green light tend to reverse the processes established by red and/or blue light. In this way, green light may be functioning in a manner similar to far-red light, informing the plant of photosynthetically unfavourable conditions. Although seemingly counterintuitive at first, these conclusions make sense in the context of normal plant growth in natural settings. In terms of basic science, together these findings remind us that nature tends not to ignore a conditional environmental input and that inductive biological systems often have antagonistic systems that counter their progression. In this way plants use the full spectrum and the relative ratios of energies within to adjust their form, composition, and physiology to best exploit prevailing conditions.

Click to expand...

Acceleration of Flowering during Shade Avoidance in Arabidopsis Alters the Balance between FLOWERING LOCUS C-Mediated Repression and Photoperiodic Induction of Flowering

The timing of the floral transition in Arabidopsis (Arabidopsis thaliana) is influenced by a number of environmental signals. Here, we have focused on acceleration of flowering in response to vegetative shade, a condition that is perceived as a decrease in the ratio of red to far-red radiation. We have investigated the contributions of several known flowering-time pathways to this acceleration. The vernalization pathway promotes flowering in response to extended cold via transcriptional repression of the floral inhibitor FLOWERING LOCUS C (FLC); we found that a low red to far-red ratio, unlike cold treatment, lessened the effects of FLC despite continued FLC expression. A low red to far-red ratio required the photoperiod-pathway genes GIGANTEA (GI) and CONSTANS (CO) to fully accelerate flowering in long days and did not promote flowering in short days. Together, these results suggest a model in which far-red enrichment can bypass FLC-mediated late flowering by shifting the balance between FLC-mediated repression and photoperiodic induction of flowering to favor the latter. The extent of this shift was dependent upon environmental parameters, such as the length of far-red exposure. At the molecular level, we found that far-red enrichment generated a phase delay in GI expression and enhanced CO expression and activity at both dawn and dusk. Finally, our analysis of the contribution of PHYTOCHROME AND FLOWERING TIME1 (PFT1) to shade-mediated rapid flowering has led us to suggest a new model for the involvement of PFT1 in light signaling.

Click to expand...

Light signals and flowering


......

Light quality and flowering

Plants grown under canopy shade conditions or in the proximity of other plants show a range of responses to the change in red (R) to far-red (FR) ratio of the ambient light. This response, known as the shade-avoidance or near neighbour detection response is characterized by increased internode extension, reduced leaf area and acceleration of flowering (Halliday et al., 1994). Many of the characteristics of the shade avoidance response can be mimicked by a short end-of-day FR treatment, implicating light-stable phytochrome as the photoregulator. PHYB is a major player in this response, but there is redundancy with PHYD and PHYE such that double or triple mutants show increasingly extreme phenotypes (Halliday et al., 1994; Aukerman et al., 1997; Devlin et al., 1998, 1999). Mutants in PHYB in Arabidopsis flower earlier than WT in both LD and SD but retain a differential response to daylength indicating a light-dependent non-photoperiodic regulatory pathway. Both light-dependent pathways, photoperiodic and light quality, act through the regulation of FT. Regulation of FT by PHYB occurs through the nuclear protein, PHYTOCHROME AND FLOWERING TIME 1 (PFT1) (Cerdan and Chory, 2003). Another characteristic of this pathway is that the early flowering phenotype in the absence of PHYB is temperature sensitive (Halliday et al., 2003). As other aspects of the shade-avoidance response do not show the same response to temperature, sensitivity lies in a flowering-specific branch of the PHYB signalling pathway.

PHYB acts through FT, implying that the light quality pathway is leaf-based. This is supported by experiments with enhancer trap lines that showed suppression of FT expression by PHYB expressed in mesophyll cells (Endo et al., 2005). In pea, however, the inhibitory effect of PHYB on flowering was found not to be graft-transmissible, in contrast to the photoperiodic effect of PHYA (Weller et al., 1997). One difference between pea and Arabidopsis appears to be that, in pea, a transmissible inhibitor is linked to the effect of PHYA whereas in Arabidopsis, control by events in the leaf is mediated entirely through FT, a floral promoter.


Light quantity responses

While increased light levels are usually accepted as having a positive effect on flowering, the plant response to light quantity for flowering is very variable. In a study of 41 herbaceous species, 10 were found to have a facultative irradiance response while 28 were unaffected (Mattson and Erwin, 2005). Interestingly, three species in this study had a negative response to increasing irradiance. In general, light quantity responses are assumed to be linked to photosynthesis and the availability of assimilates, the photoreceptors in this case being chlorophylls and other photosynthetic pigments. This idea is supported by experiments in which a strong irradiance dependence on flowering in Brassica campestris could be eliminated by supplying sucrose (Friend, 1984). Bagnall and King (2001) found that flowering was delayed under low irradiance in PHYA mutants, but not at higher irradiances, and suggested that part of PHYA action was mediated indirectly through photosynthesis although it is not clear how such a mechanism might operate.

Light quantity seems to be particularly important during early development, particularly with herbaceous species that show a clear juvenile phase (Perilleux and Bernier, 2002). It is proposed that the inability to flower during this juvenile period is because of a foliar inability to produce floral signals and/or of the competence of the apex to respond (Zeevaart, 1985; McDaniel, 1996; McDaniel et al., 1996). The length of the juvenile phase in photoperiod-sensitive plants can be revealed by reciprocal transfers between permissive and non-permissive daylengths. Such experiments with Petunia showed that the length of the juvenile phase is prolonged at lower irradiances (Adams, 1999).

What is not clear is the precise molecular mechanisms by which irradiance, if acting through photosynthetic assimilation, can modify the length of the juvenile phase. It may well be that assimilates themselves act as part of a complex flowering signal (Perilleux and Bernier, 2002; Bernier and Perilleux, 2005) or it may be that the delivery of the mobile flowering signals such as FT is dependent upon a sufficient mass flow of assimilates. One factor inhibiting a resolution of this issue is that the juvenile phase is very short in Arabidopsis and experimental separation of source–sink relationships in very young seedlings is difficult to achieve in a manner that is comparable to the extended juvenile phase of many herbaceous species.



Conclusions

Physiological studies over a long period have shown that light acts to regulate flowering through the three main variables of quality, quantity, and duration (Fig. 1). Intensive molecular genetic and genomic studies with the model plant Arabidopsis have given considerable insight into the mechanisms involved, particularly with regard to quality and duration. The Arabidopsis model is now being extended to other plants, including crops and different response types and a range of variations can be expected to emerge as more studies are undertaken. Light quantity effects, on the other hand, are still incompletely understood but are likely to be linked either directly or indirectly to patterns of assimilate partitioning and resource utilization within the plant.

Click to expand...

Green light affects organ growth and stature


The only difference was a significant component between 580–600 nm. The authors conclude that this band of wavelengths generates negative effects on plant growth, in agreement with the green light data presented in Went (1957) and Klein et al. (1965). These reports present a common theme of a negative role for 500–600 nm light in plant growth.

Click to expand...

Green light opposes stomatal opening


Green light effects on leaf growth and stomatal conductance


A connection to plant biomass

Click to expand...

Conclusions

Recent findings of cry-dependent and cry-independent green photoresponses suggest that green, in addition to red, far-red, blue, and UV sensory mechanisms, monitor and adjust plant growth and development. For the most part, the recent findings mesh well with central themes from older studies performed before the advent of molecular-genetic tools and modern techniques. One theme presented throughout this review is that the effects of green light tend to reverse the processes established by red and/or blue light. In this way, green light may be functioning in a manner similar to far-red light, informing the plant of photosynthetically unfavourable conditions. Although seemingly counterintuitive at first, these conclusions make sense in the context of normal plant growth in natural settings. In terms of basic science, together these findings remind us that nature tends not to ignore a conditional environmental input and that inductive biological systems often have antagonistic systems that counter their progression. In this way plants use the full spectrum and the relative ratios of energies within to adjust their form, composition, and physiology to best exploit prevailing conditions

Click to expand...

the effects of green light tend to reverse the processes established by red and/or blue light. In this way, green light may be functioning in a manner similar to far-red light, informing the plant of photosynthetically unfavourable conditions.

Click to expand...

In this way plants use the full spectrum and the relative ratios of energies within to adjust their form, composition, and physiology to best exploit prevailing conditions

Click to expand...

Can you describe specific symptoms of what this would look like?

Click to expand...

So if 3 color peaks make a number of harmonics, think of the richness of white light. The variability of the available energy at any given point in time. (Symphony vs two man band)
Could be avoiding "square peg round hole" situations where the proper frequency of light is not present and the plant has to improvise.

Click to expand...

Do you think that the white improved the plants, or it hurt them.
Do you think the green caused the stretch.
Actually I really like the structure of those plants.

Click to expand...

Eh....Sorry for askin'...
Which plants do you mean ?

Click to expand...

tenthirty said:

The sick ones that are in the last set of pictures.
Or is it one?

Click to expand...