Astir Grow Led Panel Project...

[stardustsailor]

For 660 light just read/study for Phytochromes...

...Thus, the parameter R:FR, which is the ratio of the photon flux density in the 655-665 nm waveband, to that in the 725-735 nm waveband, has become the standard way of characterising daylight for photomorphogenic purposes.
http://biology.mcgill.ca/Phytotron/LightWkshp1994/2.1 Smith/Smith text.htm

High R:FR Ratios (Meaning a lot of 655-665 nm red light )

Fluorescent tubes and high pressure sodium vapor lamps are popular PAR sources in CE, and both provide R:FR ratios several times higher than sunlight. Due to the spectral properties of Pr and Pfr, changes in R:FR above ca. 1.5 do not cause a proportional change in the phytochrome photoequilibrium (Smith and Holmes 1977). Therefore, the R:FR-based neighbor detection mechanism is likely to be distorted or disabled when canopies are grown under extremely high R:FR ratios. Some experimental evidence for this idea has been provided by studies with amaranth, in which CuSO[SUB]4[/SUB] filters were used to increase the R:FR ratio of the light received by the canopies and reduce stem elongation. These studies have shown that very high R:FR ratios result in decreased (rather than increased) canopy net productivity. It is not clear whether this decrease is caused by (1) the elimination of an active sink of assimilates (i.e. the growing internodes), a change in the pattern of light penetration through the canopy (see below), or a combination of the two. In any case, these results appear to directly contradict the notion that canopy growth at high densities is limited by the diversion of photosynthate to "shade-avoidance" responses. Of course, the use of artificially high R:FR ratios may be a convenient way to obtain short-statured plants in CE, which may be desirable for many crops grown for horticultural or ornamental purposes (McMahon and Kelly 1990, Rajapakse and Kelly 1992).

Another predictable consequence of the use of extremely high R:FR ratios in CE is the elimination of phototropic responses triggered through phytochrome. Since these responses may play a role in the dynamics of gap-filling by the canopy, it is suggested that the increase in light interception over time (and therefore canopy growth) will be slowed under very high R:FR. Of course, the extent of this retardation would depend upon (1) the quantitative importance of phototropic responses in gap-filling by the shoot population, and (2), the extent to which phytochrome and B-absorbing photoreceptors play redundant roles in controlling phototropic responses in canopies.

Finally, very high R:FR, which disable the phytochrome-mediated mechanism of neighbor detection, will almost certainly result in increased size structuring in dense plant populations. From a plant grower stand-point the establishment of a strong size hierarchy in the population might have two negative consequences: reduced total yield at high densities and reduced yield uniformity.

http://biology.mcgill.ca/Phytotron/LightWkshp1994/2.3 Ballare/Ballare Text.htm

In real life,testing has shown that some strains do not tolerate ,not even one led at 660 nm...
Neither at veg ,neither at bloom...
(I think Knna,also had mentioned that exact , same thing...)
While others ,seem to get along just fine...

(Anyway,even in natural sunlight ,this band of red,has pretty diminished r.power ..)
The Natural Radiation Environment


The daylight spectrum. The light environment experienced by plants in nature is obviously complex, but a number of generalisations can usefully be made. Solar radiation outside the atmosphere is distributed according to Planck's radiation distribution law, with the sun behaving as a blackbody emitter with an apparent surface temperature approximating 5800[SUP]o[/SUP] K. From Wien's simplifications of Planck's radiation formulae, the wavelength of maximum quantum emission is ca 620 nm,whereas in energy terms it is ca 500 nm; radiant emission falls off sharply at lower wavelengths and more gradually at higher wavelengths. This means that about 55% of the radiation incident on the earth's surface falls within the 380-800 nm range of photochemical activity - which is fortunate, because photochemistry drives the energetic reactions of the biosphere via photosynthesis. Atmospheric components including ozone, oxygen, water vapour and carbon dioxide selectively absorb narrow wavelength bands, resulting in the typical radiation distribution of daylight at the earth's surface seen in Figure 1. This radiation distribution is remarkably constant, being affected little by clouds and other climatic conditions (Holmes and Smith, 1977a). Pathlength through the atmosphere is important, of course, and as pathlength increases with the sun's approach to the horizon at dusk (or dawn), refraction and Rayleigh scattering (inversely proportional to the fourth power of the wavelength) gives dawn/dusk radiation distributions with relatively elevated levels of blue light, and slightly increased levels of FR compared to daylight.
....

The light environment within vegetation canopies.

Ecologically, the most important fluctuations in radiation distribution occur when radiation interacts with vegetation. The photosynthetic pigments, the chlorophylls and carotenoids, absorb radiation over almost the whole of the visible spectrum (i.e. 400-700 nm). A small fraction of the "green" radiation is either transmitted or reflected, which is why leaves are green to our eyes. What is not so immediately obvious is that vegetation hardly absorbs any radiation between 700 and 800 nm. Thus, virtually all the incoming FR is either transmitted or reflected; i.e. the FR is scattered either through the leaf, or from the surface of the leaf. Since our visual systems are very insensitive to radiation beyond ca 700 nm, we fail to recognise that leaves should look far-red, rather than green! Figure 1 shows a typical daylight spectrum within a dense vegetation canopy, and demonstrates the marked depletion of red (i.e., R, 600-700 nm) and the relative enhancement of FR radiation within canopies.
http://biology.mcgill.ca/Phytotron/LightWkshp1994/2.1%20Smith/Smith%20text.htm



As one clearly can see in Figure 1 , under a dense vegetation canopy (dotted lines),more 630-640 nm red is absorbed by leaves ,rather than 660 nm...

As,for the rest you are right ,more or less ...
But...
1)-You are referring to really actinic green light from an actinic led (525 nm....)
Not much of this band in white leds...
Mainly peak power ,for 500-599 nm ,is at yellows (560-590 ) ..

2 ) - Some Shade Avoidance Syndrome,is needed as I 've just explained,above ...
If not ,yield is diminished...( Say....Sativas vs Indicas,concerning yields,relative to species leaf structure & area / total number of leaves )...

3) -Oh , without "cloudy days ", light antagonism & with 12 hours (at flowering ) of continuous illumination..
Plus the close distance between leaf canopy- and light source ...
Yes,plenty of photo-receptors reach and pass their saturation point.
(" All other "....It's kind of absolute ,isn't it ? ...
And I strongly trust that, nothin' in the whole Universe is absolute...
Except for some researches for green light,maybe...)


4) You should study ,also,what researches from N@S@ ,say about green light and plants grown in controlled enviroments...

There is a question. Is it necessary to prepare optimal light conditions for the photosynthesis of all leaves on the plant or not? What way is it determined? The correct decision on spectral composition of light depends very much on certain morphological characteristics of plants. There is a dependance upon the distribution of fruits along a stem (Tikhomirov, 1990). For example, cucumber has equal distribution of fruits(..or flowers ,before transforming into fruits...) along the stem. There every leaf supplies assimilate to its fruit. In this connection cucumber leaves at all layers must be provided with optimal light conditions. This requires a large portion of green rays in PAR (about 40%). Red rays in PAR (about 40%) provide high level of photosynthesis of upper leaves. Green rays penetrate into middle and lower leaves of plants. Blue rays have regulatory function, but its part in PAR is not very big (about 20%) (Tikhomirov, 1989).

http://biology.mcgill.ca/Phytotron/LightWkshp1994/1.3 Tikhomirov/Tikhomirov text.htm

 

[agios]

Dimensions :20 cm x 16 cm x 5 cm . (approx. 8" x 6" x 2 " )

Weight: approx. 2 kg. (4 lbs )

Hi again Sailor!
I am trying to guess if 6 panels with 22watt each should be "enough" for one plant, scrog in an area 85x70 ?

 

[stardustsailor]

Hi again Sailor!
I am trying to guess if 6 panels with 22watt each should be "enough" for one plant, scrog in an area 85x70 ?

It depends from desired yield...
Other than that...
6 panels will do just fine ....

 

[SirShmokealot]

-Red is too much(regarding Photosynthesis) ..Only top/young leaves will "feed" buds...Meaning buds only on tops..(potentially thick 'n' fat ,though..)
I would prefer something close to 40% - 45% for reds (=600-699 nm... With peak power ,at 630-640 nm )

-Two blue leds for 6 reds / 2 Warms is a bit too much...

-A bit more green (500-599 nm.Peak 580-599 nm ,at yellows.. ) .30%-40% ...
Regarding Photosynthesis: For older/fan leaves,to keep their healthy P.And aid at " flower bud production"...

-A bit more FR..Say at 3%-4% ,it will aid in a fast start of flowering..Also ,probably it aids maturing of flowers...

So 12 leds per panel....
I would had used 4 x reds / 4 Warm Whites / 3 cool Whites /1 blue 460-470 nm
Blue (400 – 499nm) 17%
Green (500 – 599nm) 25%
Red (600 – 699nm) 56%
Far Red (700 – 750nm) 2%

Or ...
3 reds / 4 warm whites /4 cool whites / 1 blue
Blue (400 – 499nm) 19%
Green (500 – 599nm) 29%
Red (600 – 699nm) 50%
Far Red (700 – 750nm) 2%

Or ...
2 reds / 6 warm whites / 3 cool whites / 1 blue
Blue (400 – 499nm) 19%
Green (500 – 599nm) 31%
Red (600 – 699nm) 47%
Far Red (700 – 750nm) 3%

Thank you, I was using more red because those Samsungs are more efficient @ 700mA, but I might have miscalculated. So blue should be under 20% forr certain?

 

[Hosebomber]

When discussing Phytochromes, Pfr is the active state meaning deep red or 660ish nm. The phytochromes turn 630-660nm red (Pr) into Pfr. Nearly all major plant lighting studies use 656+nm red (sometimes in conjunction with 630ish) including the NASA study which used [FONT=Geneva, Arial, Helvetica, sans-serif]peak wavelengths of 664, 666, 676, and 688nm. I would love links to any article, test, or forum post that you have that shows deep red (660 nm range) causes any decrease in production of photosynthesis or damage to plants. You stated that there was a discussion on 660nm lighting on these forums but I have yet to find it. If you could guide me in that direction it would be appreciated. You links show exactly what I was referring to. Using 660nm red increases growth and has the greatest absorption. The far red that the link is suggesting is in the 725-735nm range. Again this backs up my prior staement. That paper uses 660 as Red and 730 as Far Red. "[/FONT]Thus, the parameter R:FR, which is the ratio of the photon flux density in the 655-665 nm waveband, to that in the 725-735 nm waveband, has become the standard way of characterising daylight for photomorphogenic purposes."

As for the NASA study, it says: "green light may also have additional psychological benefits for the crew. Plant leaves readily absorb red and blue light, so absorptance is high and reflectance is low. Therefore, even healthy plants grown under red and blue LEDs alone appear gray or black to humans. Hence the addition of green LEDs to red and blue LED arrays makes plants appear green to the crew."

Likewise, the only plants that performed better with the addition of green lights where those that produced no fruit or flowers. I can provide links to those studies if you do not have them already.

 

[stardustsailor]

When discussing Phytochromes, Pfr is the active state meaning far red or 660ish nm. Nearly all major plant lighting studies use 656+nm red (sometimes in conjunction with 630ish) including the NASA study which used peak wavelengths of 664, 666, 676, and 688nm. I would love links to any article, test, or forum post that you have that shows deep red (660 nm range) causes any decrease in production of photosynthesis or damage to plants. You stated that there was a discussion on 660nm lighting on these forums but I have yet to find it. If you could guide me in that direction it would be appreciated.

Post #361 ...

As for the NASA study, it says: "green light may also have additional psychological benefits for the crew. Plant leaves readily absorb red and blue light, so absorptance is high and reflectance is low. Therefore, even healthy plants grown under red and blue LEDs alone appear gray or black to humans. Hence the addition of green LEDs to red and blue LED arrays makes plants appear green to the crew."

Likewise, the only plants that performed better with the addition of green lights where those that produced no fruit or flowers. I can provide links to those studies if you do not have them already.

Again,go to the same edited post....
Read about cucumbers...
Last time I 've checked my garden,cucumbers make both flowers and fruits...
But still they need about 40% of R.power in green* from 500nm up to 599 nm ,to grow and yield...
No matter ,of their appearance to Earth residents or astronauts...

*(Peak power ,though ,near at yellows 560-599 nm
..Not low at greens,like the 520-550 nm ..
Which happens to be the ...." small fraction of the "green" radiation,either transmitted or reflected, which is why leaves are green to our eye".....)

 

[Hosebomber]

That article is interesting in a number of ways.

"We have another situation, where fruits of a plant concentrate in the upper part of the stem. Classical example is wheat. The ear of wheat is supplied with assimilates, primarily from the upper leaves. With this crop, PAR must have approximately 60-70% red rays (Tikhomirov, 1990)."
"Cucumbers appeared to be the most greatly influenced by the spectrum of PAR. For example in red wavelengths with less than PAR of 50 Wm[SUP]-2[/SUP], plants die."

Cucumbers are not really effected by the shade avoidance and stretch that we are talking about. They are bush or vine plants (depending on specie).

I guess the question remains, what type of plant are we growing?

As for the red - far red 660nm conversation, your article backs up what I was saying 100%. I would still like to see any information you have that states 660nm red damages the plant or reduces production.

 

[stardustsailor]

Once more..

660 -680 nm red leds are used,mainly , in big scale horticulture...
Yes,of course..
-The further you move away from equator ,the less 660-680 nm light...(steeper angle of sunlight ,more atmosphere to travel trough,more absorbance..)
So...
In vast greenhouses ,set in cold climates-specially during Winter/ Spring time- supplementing the crops with 650-680 nm light ,through Phytocrome action,
they control photomorphogenesis....
The main light for P ,remains the natural sunlight....

650-680 nm leds ,are a great tool for controlling Phytochrome action...
Not so great or efficient ,regarding Photosynthesis and overall healthy growth ,if used solely....
From the other hand...
620-640 nm red light does a whole lotta better job in that,probably...(if used solely....)
That is the range of Sun's maximum quantum emission, anyway....

While, Warm White leds , are the perfect..." reds ", for plant growing....
Can grow healthy plants ,just used by themshelves,alone....
Neither 660 or 630 actinics ,can do that,if used solely......

Which led of those three examples , seems more "efficient " ,growing-wise ?

 

[stardustsailor]

That article is interesting in a number of ways.

"We have another situation, where fruits of a plant concentrate in the upper part of the stem. Classical example is wheat. The ear of wheat is supplied with assimilates, primarily from the upper leaves. With this crop, PAR must have approximately 60-70% red rays (Tikhomirov, 1990)."
"Cucumbers appeared to be the most greatly influenced by the spectrum of PAR. For example in red wavelengths with less than PAR of 50 Wm[SUP]-2[/SUP], plants die."

Cucumbers are not really effected by the shade avoidance and stretch that we are talking about. They are bush or vine plants (depending on specie).

I guess the question remains, what type of plant are we growing?

As for the red - far red 660nm conversation, your article backs up what I was saying 100%. I would still like to see any information you have that states 660nm red damages the plant or reduces production.

Let's rephrase that,for a moment ....
Should it be " the question remains, how are we growing *" ?
( Or not ? )

*What techniques are we applying ?
*We want buds all over the stem(s) or just on tops ?


For the 660 red ...
Have you read what it says ?
-decreased (rather than increased) canopy net productivity.
-and therefore canopy growth) will be slowed under very high R:FR.
-reduced total yield at high densities
-reduced yield uniformity.

Isn't that information adequate,stating that 660nm red damages the plant or reduces production ?

I've a lot more...
Have to search my SSD,though...
Gimme some time....


"....Cucumbers are not really effected by the shade avoidance and stretch that we are talking about. They are bush or vine plants (depending on specie)...."

Cucumbers are herbaceous plants...( a creeping vine,to be exact...)
Neither bush ,neither a climbing vine..
(Although they are cultivated like climbing vines ....Bigger yields,like that...)
And,trust me,they stretch, like most of other plants ,when/if in shade...
Not to mention their leaves,that become quite large , under low light/shade conditions ...

 

[Hosebomber]

For the 660 red ...
Have you read what it says ?
-decreased (rather than increased) canopy net productivity.
-and therefore canopy growth) will be slowed under very high R:FR.
-reduced total yield at high densities
-reduced yield uniformity.

Is that information adequate that states 660nm red damages the plant or reduces production ?

I've a lot more...
Have to search my SSD,though...
Gimme some time....

I'm not sure if you haven't read the article you are referring to or simply refuse to see what it says. 660nm is the RED (Pr) in the study not the Far Red (Pfr). Having a high number of 730nm Far Red will cause those things... not 660nm. It's quoted in the first portion of your post (#361).

"A specific and powerful example of this ignorance relates to the importance of the so-called far-red wavelengths (FR = 700-800 nm)."
"Each phytochrome is capable of existing in two stable forms: Pr, which absorbs maximally at ca. 660 nm, and Pfr, which absorbs maximally at ca. 730 nm."
"Since the absorption maxima are in the R and the FR, it is these wavelengths that are most important in achieving equilibrium. For this reason Smith and Holmes (1977) proposed that daylight spectra could be usefully characterized and simplified by measuring the ratio of radiation in two 10 nm wavebands centred on the absorption maxima of Pr and Pfr. Thus, the parameter R:FR, which is the ratio of the photon flux density in the 655-665 nm waveband, to that in the 725-735 nm waveband, has become the standard way of characterising daylight for photomorphogenic purposes."

You seem to have researched and have a fair amount of knowledge. This is pretty exact and directly contradicts what you have said repeatedly. 660 nm is NOT FAR RED (Pfr) it is RED (Pr). Again this states that 660nm is the perfect wavelength to use. I also search up some of Knna's info and he suggest 660nm red as well.

 

[stardustsailor]

I'm not sure if you haven't read the article you are referring to or simply refuse to see what it says. 660nm is the RED (Pr) in the study not the Far Red (Pfr). Having a high number of 730nm Far Red will cause those things... not 660nm. It's quoted in the first portion of your post (#361).

"A specific and powerful example of this ignorance relates to the importance of the so-called far-red wavelengths (FR = 700-800 nm)."
"Each phytochrome is capable of existing in two stable forms: Pr, which absorbs maximally at ca. 660 nm, and Pfr, which absorbs maximally at ca. 730 nm."
"Since the absorption maxima are in the R and the FR, it is these wavelengths that are most important in achieving equilibrium. For this reason Smith and Holmes (1977) proposed that daylight spectra could be usefully characterized and simplified by measuring the ratio of radiation in two 10 nm wavebands centred on the absorption maxima of Pr and Pfr. Thus, the parameter R:FR, which is the ratio of the photon flux density in the 655-665 nm waveband, to that in the 725-735 nm waveband, has become the standard way of characterising daylight for photomorphogenic purposes."

You seem to have researched and have a fair amount of knowledge. This is pretty exact and directly contradicts what you have said repeatedly. 660 nm is NOT FAR RED (Pfr) it is RED (Pr). Again this states that 660nm is the perfect wavelength to use. I also search up some of Knna's info and he suggest 660nm red as well.

Ohhhh..
My dear friend,this is a case of misunderstanding here....

Phytochrome has a "ground" state ..Called Pr....
When illuminated with red light at region of 655-665 nm (mainly..It still happens the same , with up to 680 nm red..),it
transforms in the " active" state of Pfr ....(It absorbs no more red now..Only FR... )
Through :
-Dark conversion
(-Break down ...It does not become Pr ,really....)
-FR radiation

Pfr transforms back to Pr state.....

Phytochromes are characterised by a red/far-red photochromicity. Photochromic pigments change their "colour" (spectral absorbance properties) upon light absorption. In the case of phytochrome the ground state is P[SUB]r[/SUB], the [SUB]r[/SUB] indicating that it absorbs red light particularly strongly. The absorbance maximum is a sharp peak 650–670 nm, so concentrated phytochrome solutions look turquoise-blue to the human eye. But once a red photon has been absorbed, the pigment undergoes a rapid conformational change to form the P[SUB]fr[/SUB] state. Here [SUB]fr[/SUB] indicates that now not red but far-red (also called "near infra-red"; 705–740 nm) is preferentially absorbed. This shift in absorbance is apparent to the human eye as a slightly more greenish colour. When P[SUB]fr[/SUB] absorbs far-red light it is converted back to P[SUB]r[/SUB]. Hence, red light makes P[SUB]fr[/SUB], far-red light makes P[SUB]r[/SUB]. In plants at least P[SUB]fr[/SUB] is the physiologically active or "signalling" state.

https://en.wikipedia.org/wiki/Phytochrome

So,it is exactly the opposite,of what you thought it was...

Red 660-680 = Pfr
Far red 710-740 =Pr

Mj is a SDP ....Short Day Flowering Plant....

To flower ,plant needs a high Pr / Pfr ratio .... (Meaning ? Yes.....A lot of FR ,if R is utilised ....
Or plenty of darkness.....
Solely ,660 nm light ,changes the 'equilibrium " of phytochrome...
Either plant needs more than 12 hours of darkness to flower fast & heavy .....
Either FRradiation is needed ,during light hours,to "compensate " the 660 light induced,phytochrome state change ..
Either no 660 light,is needed at all ...

(Just a bit,is enough... With a bit of FR ..
Either from natural sunlight in warm climates ..
Or.....Hmmmm.. From White leds....)

Else....Trouble can occur...

But in other cases ,like in ( LDP ) Long Day Flowering Plants ,or for( some species ) seedlings ,660 -680 nm light is
a powerful tool,to "shape " plants ,through photomorphogenesis..

 

[PSUAGRO.]

Same Hosebomber from 420mag??????...........great info SDS as always....I see were fighting over 660nm again

 

[guod]

let me quote SDS himself:

You're getting me pretty confused,with those lights of yours....

What I cannot get is how the heck ,with those 660 of yours
(and with a bit of FR ...) you get that good ( beautiful! ) buds...
Dunno what to say...

learning not fighting

 

[Hosebomber]

So,it is exactly the opposite,of what you thought it was...

Red 660-680 = Pfr
Far red 710-740 =Pr

You have this so wrong. The photos and links you yourself provide prove the information. Red light, generally studied at the 660nm wavelength. When the phythochrome receive this light they convert it to Pfr and switch to the active state. Per the article you linked and your wiki link. This is the reason you want a larger ratio of Red (660nm) to Far Red (730nm). Using larger amounts of Far Red (730nm) will change the phythochrome to Pr and will shut off the response or cause inhibition.

You have still not shown a single reason, link, or topic post stating that 660nm is bad for plants. Which is the true nature of this discussion.

@PSUAGRO... yes same one!

 

[stardustsailor]

You have this so wrong. The photos and links you yourself provide prove the information. Red light, generally studied at the 660nm wavelength. When the phythochrome receive this light they convert it to Pfr and switch to the active state. Per the article you linked and your wiki link. This is the reason you want a larger ratio of Red (660nm) to Far Red (730nm). Using larger amounts of Far Red (730nm) will change the phythochrome to Pr and will shut off the response or cause inhibition.

You have still not shown a single reason, link, or topic post stating that 660nm is bad for plants. Which is the true nature of this discussion.

@PSUAGRO... yes same one!

Wait...I 've to explain better....
Mj is SDP..To flower , the plant needs darkness ,at least same hours with light. More hours is ok .Not less.

First phytochrome does not convert any light....
It harvests light (photons) and converts itshelf....

.....

This is the reason you want a larger ratio of Red (660nm) to Far Red (730nm). Using larger amounts of Far Red (730nm) will change the phythochrome to Pr and will shut off the response or cause inhibition.

Well..Wrong....
This is true for Long Day plants....
The longer the day,the more red light...The more Pfr.....They flower...

Short Day plants......
The longer the day,the more red light...The more Pfr.....They do not flower...
The shorter the day the more Pr ....They flower.....

You have still not shown a single reason, link, or topic post stating that 660nm is bad for plants. Which is the true nature of this discussion.

On the contrary...
High R : FR ratio means a lot of red light...Not a lot of Pr / Pfr....

So ,if you read more carefully what happens with a lot of red light (650-680 ) aka High R : FR (meaning a lot of Pfr...... )
You 'll see ,that the last hour or so ,I 've been showing that exact thing..
660 does nothing "special " that red 620-640 won't do....
Oh,yes..It does some things...
Delayed flowering...
Maturing taking forever...
Overall hindered photosynthetic net productivity...

And some more that you have already read.......

Read more carefully,please...

I 've been studying these myshelf , for many years now....
Trust me,I know about biology,better than you probably think...



Here is some help ....

http://www.cartage.org.lb/en/themes/sciences/botanicalsciences/plantreproduction/floweringplant/Photoperiodism/Photoperiodism.htm

http://www.biologie.uni-hamburg.de/b-online/e30/30c.htm

http://bcs.whfreeman.com/thelifewire/content/chp39/3902002.html

http://botanydictionary.org/phytochrome.html

http://mail.dilworth.school.nz/Subjectpages/Science/BIOLOGY/Interactive/daylength.html

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=32&ved=0CCcQFjABOB4&url=http://www.dominican-portstewart.org.uk/downloads/science/plant_physiol/phytochrome1.doc&ei=LUl7UPacJcbatAb9x4HYBQ&usg=AFQjCNHX6PTPQdj8nFSFuNKVF5tq6AUzMQ

Light-emitting diodes to understand the flowering response of a short-day strawberry

Takeda and Newell (2006) have observed that short-day strawberries that are grown in the greenhouse under long-day conditions can be induced to flower in the fall without exposure to cool temperatures or short days. This unexpected result was attributed to very high planting density (200 plant/m[SUP]2[/SUP]) of the plug plants in the greenhouse. Takeda et al. (200 stated that broad spectra light was absorbed by the canopy, but only wavelengths greater than 700 nm were being detected by the crown, resulting in an &#934; < 0.2 at crown level. It was hypothesized that the early flowering response was phytochrome-mediated. To test this hypothesis, high-density strawberries were established under long days in a greenhouse (&#934; = 0.62) and then transferred to a controlled environment chamber with broad spectra fluorescent lamps (&#934; = 0.66) under long-day conditions (16-h light/8-h dark). A strand of low-output red LEDs (&#955;[SUB]max[/SUB] = 662) was used to illuminate the crown and increase the &#934; to 0.75 (Fig. 6). This treatment was applied for 28 d and then the plants were transplanted in the field under a high tunnel production system.

After 2 months under high tunnel conditions, 83% of the plants without the supplemental red LED treatment were flowering, whereas less than half (47%) of the plants with the LED treatment were producing flowers. These data strongly suggested the maintenance of the vegetative state of the crown under short-day plants is under phytochrome control and suggests that manipulation of the crown light environment using LEDs (for sure not 660 nm leds ,for SDP though...)to promote earlier flowering could be a tool to increase off-season production of strawberry.

http://hortsci.ashspublications.org/content/44/2/231.full

 

[Hosebomber]

Wait...I 've to explain better....

First phytochrome does not convert any light....
It harvests light (photons) and converts itshelf....

Upon the absorption of radiation, Pr is photoconverted to Pfr, and Pfr photoconverted to Pr, according to the following scheme:

The absorption spectra of the Pr and Pfr forms of phytochrome isolated from etiolated oats show widely overlapping bands of absorption below ca. 730 nm, so that in broad-band radiation (such as daylight) both forms are continually photoexcited, resulting in a steady state photoequilibrium (defined as Pfr/P, where P = Pr+Pfr), in which the proportions of the total phytochrome present as Pr and Pfr are functions of the radiation distribution and of the absorption cross sections of Pr and Pfr. Since the absorption maxima are in the R and the FR, it is these wavelengths that are most important in achieving equilibrium.[/QUOTE]

So ,if you read more carefully what happens with a lot of red light (650-680 ) aka High R : FR (meaning a lot of Pfr...... )
You 'll see ,that the last hour or so ,I 've been showing that exact thing..
660 does nothing "special " that red 620-640 won't do....
Oh,yes..It does some things...
Delayed flowering...
Maturing forever...
Overall hindered photosynthetic net productivity...

And some more that you have already read.......

Nowhere in any article does anything say that happens from 660nm light. It states that happens from having too much FR.

I'm not sure where your last diagram came from but it directly contradicts your prior statement of:

Red 660-680 = Pfr
Far red 710-740 =Pr

 

[stardustsailor]

Please ,just study a bit,since you are interested....

In simple terms...
660 nm light turns Pr into Pfr ..
That thing alone ,prevents a Short Day flowering Plant ,from flowering...
(Too much 660 =too much Pfr = " long day " .. )

More Pfr than Pr ....NO FLOWERING .

If Pr becomes more in the equilibrium ,flowering starts...
Always referring to SDP.

Total opposite happens with LD plants...

A high R : FR ratio means a lot of red light (655-665 ) comparing to Far red light...
That means ,most of the phytochrome will be at Pfr state....
No Flowering...
Or not good flowering....
Or very long and slow flowering ..
Always for SD plants,like mj or strawberries...

Moreover...A lot of 660 red light ....

AGAIN !!!

High R:FR Ratios(<=he is talking about light not Phytochromes.He means a lot of 655-665 nm light .)


Fluorescent tubes and high pressure sodium vapor lamps are popular PAR sources in CE, and both provide R:FR ratios several times higher than sunlight. Due to the spectral properties of Pr and Pfr, changes in R:FR above ca. 1.5 do not cause a proportional change in the phytochrome photoequilibrium (Smith and Holmes 1977). Therefore, the R:FR-based neighbor detection mechanism is likely to be distorted or disabled when canopies are grown under extremely high R:FR ratios. Some experimental evidence for this idea has been provided by studies with amaranth, in which CuSO[SUB]4[/SUB] filters were used to increase the R:FR ratio of the light received by the canopies and reduce stem elongation.These studies have shown that very high R:FR ratios(meaning much 660 nm light ) result in decreased (rather than increased)(<= this statement would be useless,if he was referring to FR light .."Increased" was expected with reds.But....) canopy net productivity. It is not clear whether this decrease is caused by (1) the elimination of an active sink of assimilates (i.e. the growing internodes), a change in the pattern of light penetration through the canopy (see below), or a combination of the two. In any case, these results appear to directly contradict the notion that canopy growth at high densities is limited by the diversion of photosynthate to "shade-avoidance" responses. Of course, the use of artificially high R:FR ratios may be a convenient way to obtain short-statured plants in CE, which may be desirable for many crops grown for horticultural or ornamental purposes (McMahon and Kelly 1990, Rajapakse and Kelly 1992).

Another predictable consequence of the use of extremely high R:FR ratios in CE is the elimination of phototropic responses triggered through phytochrome. Since these responses may play a role in the dynamics of gap-filling by the canopy, it is suggested that the increase in light interception over time (and therefore canopy growth) will be slowed under very high R:FR. Of course, the extent of this retardation would depend upon (1) the quantitative importance of phototropic responses in gap-filling by the shoot population, and (2), the extent to which phytochrome and B-absorbing photoreceptors play redundant roles in controlling phototropic responses in canopies.

Finally, very high R:FR, which disable the phytochrome-mediated mechanism of neighbor detection,(meaning that, plant doesn't have any Pr ,to start Shade Avoidance ) will almost certainly result in increased size structuring (that's what you gain with 660 nm leds ) in dense plant populations. From a plant grower stand-point the establishment of a strong size hierarchy in the population might have two negative consequences: reduced total yield at high densities and reduced yield uniformity.

Please,before answering ,just study some more ,about phytochrome and how it acts on SD plants......
Pfr for mj ,means vegetative growth.....(Big size structure... )
Pr means,flowering....( Also means streching and Shade Avoidance ,if in excess ..)

As simple as that...

Really,can't explain it any better than that...
If you still do not understand it ,ask a professor in plant biology....
Or search the web..
There is a lot of info....
Understanding how phytochrome works on SDP,
you'll,almost, immediately understand why 660 leds are not the best choice of reds,regarding SD plants ( i.e. mj )
...
As for Photosynthesis ,mj is a C3 plant...It utilises more CH b than CHa,like all C3 plants,without not even one exception to the rule...
Meaning ,harvesting efficiently more photons at 610-640 region ,than of 650-680 region ..
.....

 

[stardustsailor]

http://www.yale.edu/denglab/paper/Jigang2011.pdf

http://www.bio.pku.edu.cn/lab/biotech/pmb_workshop/linchentao/lin_2.pdf

http://xa.yimg.com/kq/groups/21666630/1659117910/name/17-Phytochrome-and-Light-development.pdf



Long Day plants : Plants that veg in winter (or autumn )....Flower /fruit in spring / summer ...
Most of the plants grown in greenhouses are LD plants...
660 light aids flowering / fruiting at that case....(Much Pfr )


Short Day plants : Plants that veg in spring / summer ....Flower /fruit in autumn or winter...
Most of the plants grown in....growrooms / grow tents ,belong to a certain SD specie ....
Far Red light ,aids flowering at this case... (Much Pr )
Just a tiny bit ,during light hours will do miracles ( 3%-5% ) ...

..
Nothing more to add to that topic....
The rest is out there ,all over the web...

Based on my own knowledge ,of plant biology ,650-680 nm leds ,are not the best choice of reds for mj cultivation.
620-640 nm are far more efficient ,for photosynthesis...
(Do not get misguided/misled by Photosystems P680 or P700..Anyway,plants do not photosynthesise at 700 nm...
Neither get misguided/misled from absorbsion or action spectrums measurements of phot/tic pigments ,diluted in organic diluants/solvents..
Neither from studies done in really low irradiance levels... )
To finish the subject...
660 -680 nm leds,are great ,but for greenhouses ,where,mostly, long day plants are cultivated...
Other than that ,they have a nice deep red color...Good for traffic lights or "caution"/ warning signs....
But for growing SD plants .....Eh...
At least ,mj is proven ( i.e. Mr X .Evo V3 .Red 630 + White 10.000° K ) to grow really good and fine ,with good ol' 630s'....

 

[Hosebomber]

As some of the guys here can tell you from reading my post on other forums, I've been doing this for quite a while as well. It's obvious that you are going to continue to not read your own links and make wild assumptions. Turning off our lights for the 12/12 flowering cycle is what causes the Pfr to change back to Pr to induce flowering... This has been known for decades and why we do it. 660nm is used in all of these studies because it has the best absorption level for Chlorophyll and other accessory pigments. Yes it helps plants vegetate, and keeping them in the light for more than 12 hours will keep them in the vegetative state (they are a SDP as you mention). The phytochromes are not the only portion of the plant that needs to be considered when growing. It is actually one of the smallest factors because we control them by turning the lights out for 12 hours when it is time to flower.

• • P[SUB]R[/SUB] because it absorbs red (R;660 nm) light
  • P[SUB]FR[/SUB] because it absorbs far red (FR; 730 nm) light
• These are the relationships:
  • Absorption of red light by P[SUB]R[/SUB] converts it into P[SUB]FR[/SUB]
  • Absorption of far red light by P[SUB]FR[/SUB] converts it into P[SUB]R[/SUB].
  • In the dark, P[SUB]FR[/SUB] spontaneously converts back to P[SUB]R[/SUB].
• Sunlight is richer in red (660 nm) than far red (730 nm) light so at sundown, all the phytochrome is P[SUB]FR[/SUB].
• During the night, the P[SUB]FR[/SUB] converts back to P[SUB]R[/SUB].

One last thing on the Pfr. A short burst of high levels of 730nm Far Red can reduce the "night" time requirement by upto 2 hours. This is the reason for the "Flower Initiator" being sold.

I'm sure you can find many examples of LED panels using 660nm red leds that have and will produce better than your panels. Maybe you should try to add some and see your results. Likewise, If you wish. I will be more than happy to do a grow with "your" design and one of mine side by side for comparison.

 

[stardustsailor]

Turning off our lights for the 12/12 flowering cycle is what causes the Pfr to change back to Pr to induce flowering... This has been known for decades and why we do it. 660nm is used in all of these studies because it has the best absorption level for Chlorophyll and other accessory pigments. Yes it helps plants vegetate, and keeping them in the light for more than 12 hours will keep them in the vegetative state (they are a SDP as you mention).

Not exactly....650-680 nm light is solely harvested by Chlorophyll A ,abundant mainly,in
C4 plants like corn....Chlorophyll B ,also absorbs some photons at 650-680 range...Just a small percentage though...Other Photosynthetic or accessory pigments*,absorb photons of other wls...Much shorter than 660 nm...
(* Lutein ,zeaxanthin,other xanthophylls,carotenoids like &#946;-carotene,lycopene,anthocyanin and some other flavonoids,ect )

The phytochromes are not the only portion of the plant that needs to be considered when growing. It is actually one of the smallest factors because we control them by turning the lights out for 12 hours when it is time to flower.

You seriously think so ?
How did you end up with this assumption ?
Who told you that ?
Where did you read such a thing ?
Because science has a very different opinion from yours...
Way different......i.e......

I do not believe that we have to copy illumination of plants in natural conditions for use in controlled environment growing. For example there's no need to grow some species of plants under alternative light dark periods. Our research showed that productivity of some plants (radish, wheat) can be increased under continuous irradiation (Tikhomirov et al., 1976; Lisovsky et al., 1987). Also, we should not strictly aspire to duplicating morphophysiological characteristics of field grown plants. Thus, for example, we achieved a very large radish productivity when we sharply changed its photomorphogenesis (Tikhomirov et al., 1976). This is true for increasing cucumber productivity too. However, if we accept this concept, we must know where and how we should deviate from natural conditions to increase productivity of plants grown in controlled environments.
http://biology.mcgill.ca/Phytotron/LightWkshp1994/1.3 Tikhomirov/Tikhomirov text.htm

Think once more about Sativas vs Indicas...They've evolved under different light characteristics overall,amongst others...
With the Sativas ,being the " light blessed ",considering light...
A lot of irradiation,more hours under the sun and richer spectrum....
More photosynthesis ?
Well ,yield,is way less ,than the "light cursed " Indicas...
So..
I 've to reverse your phrase...
Photosynthesis is not the only portion of the plant that needs to be considered when growing.
Because we can,relatively easy, control photomorphogenesis (phytochromes,mainly..) ,by light duration,quantity,quality and spatial coverage/direction/diffusion ,phytochromes and thus photomorphogenesis,is the best available tool ,a grower has ,to affect/alter drastically and dramatically plant growth and yields....

.........

• • P[SUB]R[/SUB] because it absorbs red (R;660 nm) light
  • P[SUB]FR[/SUB] because it absorbs far red (FR; 730 nm) light
• These are the relationships:
  • Absorption of red light by P[SUB]R[/SUB] converts it into P[SUB]FR[/SUB]
  • Absorption of far red light by P[SUB]FR[/SUB] converts it into P[SUB]R[/SUB].
  • In the dark, P[SUB]FR[/SUB] spontaneously converts back to P[SUB]R[/SUB].
• Sunlight is richer in red (660 nm) than far red (730 nm) light so at sundown, all the phytochrome is P[SUB]FR[/SUB].
• During the night, the P[SUB]FR[/SUB] converts back to P[SUB]R[/SUB].

One last thing on the Pfr. A short burst of high levels of 730nm Far Red can reduce the "night" time requirement by upto 2 hours. This is the reason for the "Flower Initiator" being sold.

So ? ...What you 've just described is the " dusk" or "sunset effect"...
What is new here ?
Further more ,one can go for a reduction of more than 2 hours...
I'd say to about double...
You can still flower with 8 hours of darkness....
But with much more complicated FR illumination schedule than just "flashin' " the plant with FR...
(Allow me to uncover how this is done,when I'll think it is an appropriate time to do so ...)
Until then,just forget that I've mentioned it,already.. )

I'm sure you can find many examples of LED panels using 660nm red leds that have and will produce better than your panels. Maybe you should try to add some and see your results. Likewise, If you wish. I will be more than happy to do a grow with "your" design and one of mine side by side for comparison.

At this wattage and with such crappy and cheap leds,of mine ?
With no lenses to " focus " power ?
With crappy drivers ?
Please,allow me ,to seriously doubt that..
Really.
I never 've seen something like that ...
Not even close...

Try my config with really high quality leds/drivers ..
Same watt for watt ,with a panel of actinics of same quality/brand/bin/whateva...
At whatever wls you like/wish 630,660,450 ,460,ect.. )
..
I'll be waiting for your results...
(Not that I 'll be suprised,though... )

As for my side,of experiment...
I 've already tried 650-660-670-680 nm leds...
Result :
Nop...
Never ,again...
Plants and yield ,was to be laughed at...
( With same crappy ,cheapo quality of leds...)

The difference between" white mixes " and " actinic mixes " ,regarding CE growing ,is HUGE !

P.S. :
Also,there are a lot of people ,who can verify ,what I've supported ,when I saw,for first time, the new-to-be-released EVO 4..
The one with the oslons 80s'... (Neutral White +Red 660 nm ) .
Have you seen a single grow with 'em ?
'Cause I haven't....
It must 've been a really successful combo of leds...
So much,that it never reached mass production...
And the company ,just "disappeared "....
???
Although EVO V3 ,was a piece of art,with the simplest combo ever ...
630s'+Cool Whites...
( In fact,at 10.000 ° K ,they should be called " cold whites " ...)
.....