Astir Grow Led Panel Project...

SDS said in #535: More N (dry mass / plant cell proteins ) assimilated by the plant(s) ,more energy (number of photons to drive PS ,thus red.. ) needed...
And vice versa...

Also ,of course ,More PS ,means more CarbonHydrates...
Meanin' more energy (simple sugars ) and also more plant mass ( polymerised sugar molecules to form long or /and complex chains aka cellulose / hemicellulose /lignin /pectin /ect,as main plant "building " material ...Mainly at stalks and branches... )

But flowers need also a good deal of N and K assimilation ,along with long/complex sugar chains...

Still ,one has to be really careful ,not to utilise too much red..
( Or the ..guh..uhm...Kinda " wrong " wls of red ...) ...
Stomata close ,CO2 is starting to be limited...
Let alone the Phytochrome ratio anomalies & alterations ....
Everythin' should be in " balance "...
No room for "extremes" or "compromises " here...
Otherwise one needs more than 400 Watt of leds to get a decent harvest...
No way, back to those powers....
250 Watt at max,instead...

Goal is to have a better yield (both regardin' quality & quantity ) -than from 400 Watt HPS-,
with 250 Watt (or less).With the "right" config & combo of leds...

Astir team won't stop until this is accomplished,with the easiest,most flexible and cheapest way,possible...
Meanin',as overall ( average indoor gardener's-wise ) efficiently,as possible ..

I totally agree. One of the reasons why I switched to hydro (3 different methods) is optimal control over pH, ppm/ec + temperature- warmer in veg, cooler in flower- just like nature.

Balanced lighting (that which the strain prefers) + ok nutes = ok results. Great nutes and unbalanced lighting (too much blue or red)= ok yields.

In mid grow last time, I switched from the whole Dutch Masters Gold line (4+ products) to Hydroponic Research VEG+BLOOM, a one step formula, with lots of N. I had a bad aphid + SM infestation that destroyed 90% of the primary and secondary leaves, but still managed a decent yield and quality product. This grow I have been using V+B since day one. It kicks ass

stardustsailor said:

And about " higher dry weight ".....
...

(from photosynthesis..thus the extra red at region 620-640 nm .C3 plants have more Ch B than Ch A).

..

Click to expand...

(from photosynthesis..thus the extra red at region 620-640 nm .C3 plants have more Ch B than Ch A).
repeated 5 times

are you sure...

The ratio of chlorophyll a to chlorophyll b in the chloroplast is 3:1.
http://www.bio.umass.edu/biology/conn.river/chlorophyll.html

In natural chlorophyll there is a ratio of 3 to 1 (of a to b) of the two components.
http://www.ch.ic.ac.uk/local/projects/steer/chloro.htm

to name a few...

Still ,one has to be really careful ,not to utilise too much red..
( Or the ..guh..uhm...Kinda " wrong " wls of red ...) ...
Stomata close ,CO2 is starting to be limited...
Let alone the Phytochrome ratio anomalies & alterations ....
Everythin' should be in " balance "...

Click to expand...

1.5. Light regulation of stomatal movements

In addition to environmental factors, stomata are controlled by an endogenous circadian
clock. This control may appear as a rhythmic change in aperture under constant conditions or as a rhythmic change in sensitivity to some environmental factor, such as light (Gorton et al., 1989; Tallman, 2004).

Stomatal opening is directly driven by light, depending on its wavelength.
Blue light stomatal response is rapid and photosynthesis-independent saturating at
lower fluences (around 50 µmol m-2s-1) (Zeiger, 2000).

Red light photosynthesis-dependent response saturates at high fluences similar to PAR (photosynthetic active radiation).
Blue light is most efficient in driving stomatal opening but red light acts as a required background for the rapid opening (Vavasseur & Ragavendra, 2005).

Stomata in Arabidopsis open fast in response to a weak blue light under a strong red light background, whereas they are almost closed under pure blue light illumination in the absence of red light (Willmer & Fricker, 1996).

http://www.botan.su.se/polopoly_fs/1.79450.1331022002!/menu/standard/file/Licentiate_thesis.pdf

-------------------------------------------
Light Regulation of Stomatal Movement

Stomatal opening is induced by light, including
blue and red light, and distinct mechanisms
underly stomatal opening in response to
these different wavelengths (193). Blue light
acts as a signal and red light as both a signal
and an energy source.

SUMMARY POINTS
1. Stomatal opening is induced by light and is mediated by two distinct photosystems:
blue-light photosystems and chloroplasts. Stomata open in response to a weak blue
light and the opening is enhanced by background red light.
...
...
...
3. Red light induces stomatal opening at high intensity. Red light likely mediates stomatal opening via reduction of the intercellular concentration of CO2 (Ci ) by mesophyll photosynthesis, but the role of guard cell chloroplasts in the response could not be excluded.

ftp://globalecology.stanford.edu/pub/joeberry/Stomata/Shimazaki_ea_annRev.pdf

---------------------------------------------

The stomatal pores of higher plants enable gaseous exchange into and out of leaves for photosynthesis and evaporation. Stomatal opening is induced by both blue and red lights. It is shown that blue light-induced stomatal opening is mediated by the blue light receptor phototropins (PHOT1 and PHOT2) and cryptochromes (CRY1 and CRY2). However, whether phytochrome B (phyB) is involved in red light regulation of stomatal opening remains largely unclear. Here, we report a positive role for Arabidopsis (Arabidopsis thaliana) phyB in the regulation of red light-induced stomatal opening.

http://mplant.oxfordjournals.org/content/3/1/246.full

@My brother Guod...

Regardin' post #542
Well partially what is claimed at those two links (amongst many others,indeed..) is true...
Partially ,what I claim is also true... ( Kinda in an indirect way ... )
Things are not so simple as a ratio ChA/ChB =3 ....
Well yes of course you find this ratio more often to C4 Species of plants..
While for C3 plants it's not quite so ...
( Chlorophylls ratios,along with other pigments ,give leaves all sorts of colors...Many different leaf colors...To " harsh " to say " Ratio is 3: 1 "...)
Also in same plant ,ratio changes amongst older leaves (lower ratios ) and new leaves (high ratios ) .
Older leaves ,also happens to be the most by numbers...

In fact ...
Each different species ( and individuals ) of plants ,have it's own ratio...
Well ...
Yes ,usually ChA is more ,under constant clean sky ,for long periods of time...
Under many hours of light...
Under deep red light.... ( yes 650-680 nm range..)

While,in reality ....
A plant as a whole ,and not just top leaves ,seems to have more in use Ch B ,than A ...

Anyway...
Think that simple....

If that what is claimed at many researches...
(Are always totally & absolutely correct ? ...
I mean that,history ,many times showed / proved the opposite....
Once the Earth " was " Flat....
For pretty long time,I should add....
I trust what I see with my own eyes and measurements...)
Was standing absolutely true..
Ch A / Ch B = 3 /1 .-
Then those chunks of Astir panels ,should not be working at all...
Because they provide lots of " Ch B red light ( with a bit " ChA blue light " ) ...
Not much " Ch A red light " ,there.....
There is a rather small amount....

-Plants adapt,also...
They can change the Ch ratio,during early vegetative stages.....

As for post #543 ,I could not agree more ...
Nothing strange there....

Wish I could sit and write more ,with some references....
Just came back from a hard day's work...
I'll have a cold shower and try to explain the whole Ch thing...

But anyhow....
It's rather complicated issue,that also in the botanical/horticultural science has been creatin',oftenly " issues "....
( Hope that will not try to solve them,here at this forum....It gonna take really long.... Things there are quite hazy....)


What ,really, we should be looking/searchin' for an answer , is this simple thing ...
Repeated probably about as same as many times ....
The Sativa vs Indica example,regarding average flower production and light quantity / quality of natural enviroment..( stimulus ) ...

If we start going deeper ,one notices that somethin' isn't quite as " right " regarding Chlorophylls ....

The "smaller sister" Ch B ,seems to be more workaholic,my brother...
While the " big and strong " Ch A...How should I put it ? She is a stoner...
Yeap...It might be affecting overall quality,also ...
But ...Well she likes to work on the highest part of " structure "..
At tops...
Going at lower levels (higher by numbers,though-if you understand what I mean..) ,things change...

Anyway..
As I mentioned...
They are not totally wrong ,but they are not totally right,also....

If things where as they say...
Astir panels wouldn't be able to grow anythin' ...
That I can tell....

guod said:

(from photosynthesis..thus the extra red at region 620-640 nm .C3 plants have more Ch B than Ch A).
repeated 5 times

are you sure...

The ratio of chlorophyll a to chlorophyll b in the chloroplast is 3:1.
http://www.bio.umass.edu/biology/conn.river/chlorophyll.html

In natural chlorophyll there is a ratio of 3 to 1 (of a to b) of the two components.
http://www.ch.ic.ac.uk/local/projects/steer/chloro.htm

to name a few...

Click to expand...

Oh no. Decention within the ranks

As for the "workaholic" Chlorophyll B .....
Amongst others..

Light Intensity-Dependent Modulation of Chlorophyll b Biosynthesis and Photosynthesis by Overexpression of Chlorophyllide a Oxygenase in Tobacco1,[C][OA]

Ajaya K. Biswal,2 Gopal K. Pattanayak,2 Shiv S. Pandey, Sadhu Leelavathi, Vanga S. Reddy, Govindjee, and Baishnab C. Tripathy*
Author information ► Article notes ► Copyright and License information ►
Go to:

Abstract

Chlorophyll b is synthesized by the oxidation of a methyl group on the B ring of a tetrapyrrole molecule to a formyl group by chlorophyllide a oxygenase (CAO). The full-length CAO from Arabidopsis (Arabidopsis thaliana) was overexpressed in tobacco (Nicotiana tabacum) that grows well at light intensities much higher than those tolerated by Arabidopsis. This resulted in an increased synthesis of glutamate semialdehyde, 5-aminolevulinic acid, magnesium-porphyrins, and chlorophylls. Overexpression of CAO resulted in increased chlorophyll b synthesis and a decreased chlorophyll a/b ratio in low light-grown as well as high light-grown tobacco plants; this effect, however, was more pronounced in high light.

The increased potential of the protochlorophyllide oxidoreductase activity and chlorophyll biosynthesis compensated for the usual loss of chlorophylls in high light.Increased chlorophyll b synthesis in CAO-overexpressed plants was accompanied not only by an increased abundance of light-harvesting chlorophyll proteins but also of other proteins of the electron transport chain, which led to an increase in the capture of light as well as enhanced (40%–80%) electron transport rates of photosystems I and II at both limiting and saturating light intensities. Although the quantum yield of carbon dioxide fixation remained unchanged, the light-saturated photosynthetic carbon assimilation, starch content, and dry matter accumulation increased in CAO-overexpressed plants grown in both low- and high-light regimes. These results demonstrate that controlled up-regulation of chlorophyll b biosynthesis comodulates the expression of several thylakoid membrane proteins that increase both the antenna size and the electron transport rates and enhance carbon dioxide assimilation, starch content, and dry matter accumulation.

Light intensity is a major determinant of photosynthesis and plant growth. Under a low-light (LL) regime, both photosynthetic rate and crop productivity are low. Thus, it is essential to increase the rate of photosynthesis at LL intensity by efficiently harvesting the low amount of available solar energy. Solar energy is mostly captured by a light-harvesting chlorophyll protein complex (LHC) of the photosynthetic apparatus. In higher plants, both chlorophyll a (Chl a) and chlorophyll b (Chl b) are bound to the LHCs. The availability of Chl b is essential for the assembly and functioning of most LHC proteins (Bellemare et al., 1982; Peter and Thornber, 1991). Binding of Chl b to the LHC proteins stabilizes the latter in the thylakoid membranes (Paulsen et al., 1993; Lindahl et al., 1995). Therefore, in the absence of Chl b, the LHC proteins decrease (Thornber and Highkin, 1974; Murray and Kohorn, 1991; Murchie and Horton, 1997), partly due to the degradation of unbound LHC apoproteins by proteases (Hoober and Eggink, 2001). Under high light (HL) intensity, plants have a low amount of Chl b and a small LHC antenna, whereas plants grown under LL intensity accumulate more Chl b and have a bigger LHC antenna (Björkman et al., 1972; Leong and Anderson, 1984). This indicates the parallel regulation of Chl b biosynthesis and LHC proteins.

Chl b is synthesized from Chl a by oxidation of a methyl group on the B ring, of the latter molecule, to a formyl group at that position (Porra et al., 1993). The main function of Chl b is to gather light energy and transfer it to Chl a (Duysens, 1952). The gene encoding chlorophyllide a oxygenase (CAO), responsible for Chl b synthesis, has been isolated (Tanaka et al., 1998; Espineda et al., 1999; Tomitani et al., 1999; Nagata et al., 2004; Lee et al., 2005), and the recombinant CAO protein catalyzes the oxidation of chlorophyllide (Chlide) a to Chlide b (Oster et al., 2000). The mRNA and protein expression of CAO is highly regulated by light intensity, and the expression of CAO changes in parallel to that of lhcb (Masuda et al., 2003; Harper et al., 2004; Pattanayak et al., 2005; Tanaka and Tanaka, 2005). It is apparent that the regulation of CAO expression under different light intensities contributes significantly to control Chl b synthesis and consequently the chlorophyll a/chlorophyll b (Chl a/b) ratio in plants. Overexpression of CAO resulted in increased Chl b and LHCII levels, suggesting that enhanced CAO mRNA affects the size of LHCII (Satoh et al., 2001; Tanaka et al., 2001; Pattanayak et al., 2005; Tanaka and Tanaka, 2005). Further study on CAO overexpression in the cyanobacterium Synechocystis also revealed Chl b synthesis (Satoh et al., 2001), and simultaneous overexpression of both CAO and LHCP II in Synechocystis led to increased Chl b content that disturbed tetrapyrrole biosynthesis (Xu et al., 2001, 2002).

The CAO sequence has been classified into four parts: (1) the N-terminal transit peptide; (2) the regulatory A domain; (3) the B domain; and (4) the C domain that is sufficient for its catalytic activity (Nagata et al., 2004). The Clp protease and the A domain are involved in the regulation of Chl b biosynthesis through the destabilization of CAO by sensing the presence of overaccumulated Chl b (Yamasato et al., 2005; Nakagawara et al., 2007; Sakuraba et al., 2009). As the A domain of CAO regulates the level of CAO and thus prevents the excess accumulation of Chl b, overexpression of A domain-deleted CAO in Arabidopsis (Arabidopsis thaliana) results in the overaccumulation of Chl b. Consequently, the plants become vulnerable to photodamage, specifically when etiolated transgenic plants are exposed to either LL or HL immediately after etiolation (Yamasato et al., 200. Similarly, overexpression of Prochlorothrix CAO, which lacks the regulatory A domain, in Arabidopsis led to the overaccumulation of Chl b, and the transgenic plants were photodamaged under HL intensity (Hirashima et al., 2006). From these studies, it is clear that unregulated excess accumulation of Chl b is deleterious for plants; therefore, overexpression of the A domain-deleted CAO protein in plants would not be useful in increasing the photosynthetic efficiency of the plants.

We have previously reported that overexpression of Arabidopsis full-length CAO (AtCAO) results in increased Chl b synthesis and decreased Chl a/b ratio in LL- and HL-grown tobacco (Nicotiana tabacum) plants (Pattanayak et al., 2005). In this study, we show that the overexpression of AtCAO modulates the flux of the chlorophyll biosynthesis pathway, leading to increased Chl b and total chlorophyll synthesis both in LL- and HL-grown transgenic tobacco plants. We further show that increased Chl b biosynthesis in AtCAO-overexpressing (CAOx) plants results in increased amounts of light-harvesting antenna proteins, efficient capture of solar energy, and increased electron transport at limiting as well as saturating light intensities. Furthermore, CAOx plants have increased carbon dioxide (CO2) fixation, starch content, and dry matter accumulation. These results suggest that engineering plants for larger antennae may have the potential for increasing photosynthesis in plants.

Click to expand...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3375976/

Take a microscopic view.

Chlorophylla-a is the primary pigment for photosynthesis in plants. Its structure is shown at left. It has the composition C[SUB]55[/SUB]H[SUB]72[/SUB]O[SUB]5[/SUB]N[SUB]4[/SUB]Mg. It exhibits a grass-green visual color and absorption peaks at 430nm and 662nm. It occurs in all photosynthetic organisms except photosynthetic bacteria.
Chlorophyll-b has the composition C[SUB]55[/SUB]H[SUB]70[/SUB]O[SUB]6[/SUB]N[SUB]4[/SUB]Mg, the difference from chlorophyll-a being the replacement of a methyl group with a CHO. It exhibits a blue-green visual color and absorption peaks at 453nm and 642nm. It occurs in all plants, green algae and some prokaryotes. There is usually about half as much chlorophyll-b as the -a variety in plants.

http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/pigpho.html#c1

Click to expand...

....
Ok ..Here they state the ratio to be 2: 1 .....
( Whom I 'm supposed to trust ? ....
At least they are more " rational " (!) and they mention the word " usually "... )

The photosynthetic efficiency is the fraction of light energy converted into chemical energy during photosynthesis in plants and algae. Photosynthesis can be described by the simplified chemical reaction
H[SUB]2[/SUB]O + CO[SUB]2[/SUB] + energy → CH[SUB]2[/SUB]O + O[SUB]2[/SUB], where CH[SUB]2[/SUB]O represents carbohydrates such as sugars, cellulose, and lignin. The value of the photosynthetic efficiency is dependent on how light energy is defined. On a molecular level, the theoretical limit in efficiency is 25%[SUP][1][/SUP] for photosynthetically active radiation at the Chlorophyll-a absorbance peak (wavelength of 680 nanometers). However, photosynthesis is now known to occur up to 720 nm wavelengths (see Chlorophyll). For actual sunlight, where only 45% of the light is photosynthetically active, the theoretical maximum efficiency of solar energy conversion is approximately 11%. In actuality, however, plants do not absorb all incoming sunlight (due to reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels) and do not convert all harvested energy into biomass, which results in an overall photosynthetic efficiency of 3 to 6% of total solar radiation.[SUP][1][/SUP] If photosynthesis is inefficient, excess light energy must be dissipated to avoid damaging the photosynthetic apparatus. Energy can be dissipated as heat (non-photochemical quenching), or emitted as chlorophyll fluorescence.



Starting with the solar spectrum falling on a leaf,
47% lost due to photons outside the 400–700 nm active range (chlorophyll utilizes photons between 400 and 700 nm, extracting the energy of one 700 nm photon from each one)
30% of the in-band photons are lost due to incomplete absorption or photons hitting components other than chloroplasts
24% of the absorbed photon energy is lost due to degrading short wavelength photons to the 700 nm energy level
68% of the utilized energy is lost in conversion into d-glucose
35–45% of the glucose is consumed by the leaf in the processes of dark and photo respiration
Stated another way:
100% sunlight → non-bioavailable photons waste is 47%, leaving
53% (in the 400–700 nm range) → 30% of photons are lost due to incomplete absorption, leaving
37% (absorbed photon energy) → 24% is lost due to wavelength-mismatch degradation to 700 nm energy, leaving
28.2% (sunlight energy collected by chlorophyl) → 32% efficient conversion of ATP and NADPH to d-glucose, leaving
9% (collected as sugar) → 35–40% of sugar is recycled/consumed by the leaf in dark and photo-respiration, leaving
5.4% net leaf efficiency.


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

^^this is one of the reasons I stuck to AG instead of Hort @ PSU ....I took organic chem THREE times!!/lol......skipped right over advanced genetics/plant cell-molecular biology/Advanced physiological ecology/ etc...............smoked too much durban back then, to even think about passing/understanding this level of info.........good stuff SDS...

stardustsailor said:

Uhm...
One way is to study them at a university (Botany/ Higher plants Biology )
Another way is to study them ,using the "open university classes ", web has to offer...
A good startin' point is here...
http://analysis3.com/Physiology-Of-Higher-Plants-An-Outline---McGoodwin-Family-Website-pdf-e31662.pdf




Just an outline though...
But a decent one...

Click to expand...

Thank you! After I read this, I'll be able to decode these past 25 pages..... Maybe..

...
I just want to explain,the whole thing ,in a more simplistic way...
You'll probably have to excuse me ,if I'll not manage to do that ,at the fullest,due to language limitations..

Lets talk about "reds" (600-699 nm ) and irradiance...
Lets set aside "blues" ( 400-499 nm ) & greens (500-599 nm )...For a moment...



" Ch A reds " = high number of photons wls= 650-680 nm (up to 720 nm ,in some cases )

Many C4 Plants ,like the really " efficient " sugarcane ,utilise ChA at the fullest to succeed in extraordinary photosynthetic rates...
( High Ch A / Ch B ratios ) ..
C4 plants have usually sun adapted leaves....
Like sugar cane ...


Notice somethin' "weird" ?
Healthy leaves on tops...
Where red light of 650-680 nm is really abundant ..
Absorbed pretty much & easily..
- So leaves on top of plants,utilise most of deep reds ...

Remember also :" We have another situation, where fruits of a plant concentrate in the upper part of the stem. Classical example is wheat.( C3 plant ) 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)."
http://biology.mcgill.ca/Phytotron/LightWkshp1994/1.3 Tikhomirov/Tikhomirov text.htm

Click to expand...

- Through Photomorphogenesis and phytochrome action ( Low Pr / Pfr ratios ),plants illuminated with 650-680 nm red become sun adapted.
That means ,that they need quite high total irradiances to produce...(Many Watts of leds .... )

Photosynthetic Light Response
The photosynthetic response of individual leaves to irradiance level has been studied
extensively and is fundamental to our understanding of adaptation to sun and shade
(Bjorkman 1981). The paradigmatic study of Bjorkman et al. (19723) on acclimation
of the photosynthetic light response to irradiance in Atriplex triangularis (then known
as A. patula) provides perhaps the best illustration of the characteristic differences in
response seen in leaves grown under sunny v. shady conditions, and has been widely
used to support the view that such differences (and related morphological and physiological
traits) are adaptive. Yet, an unnoticed aspect of this classic study seems to
undercut its support for adaptive variation in photosynthetic response; as shown below,
this support re-emerges if the data are reanalysed in terms of energetic tradeoffs at the
whole-plant level.
Bjorkman et al. (19723) grew seedlings of Atriplex triangularis in growth chambers
under a 16 h photoperiod at one of three different irradiance levels: high (920 pmol
Adaptation to Sun and Shade
m - s - '), intermediate (290 pmol m - s - '), and low 92 pmol m - s - I). They then
measured the net photosynthetic rate per unit area of leaves acclimated to these conditions
as a function of irradiance ranging from 0 to 2500 pmol m-2 s- '.
Bjorkman et al. (1972b) regarded the photosynthetic responses of leaves acclimated
to different irradiance levels to be adaptive to those levels for three reasons. First, leaves
grown at high irradiance had a higher maximum photosynthetic rate, and higher rate
at high irradiances (>c. 450 pmol m-2 s- '), than leaves grown at intermediate or low
irradiance. Second, leaves grown at low irradiance had lower respiration rates than
those acclimated to other irradiance levels. Given that all leaves showed the same initial
slope (quantum yield) relating photosynthesis to irradiance, the lower respiration rate
of leaves acclimated to low irradiance resulted in their having a lower light compensation
point (i.e. the irradiance at which the instantaneous leaf rates of gross photosynthesis
and respiration just balance). Consequently, at the lowest irradiances leaves grown at
low irradiance had the highest net photosynthetic rate. Finally, leaves grown at intermediate
irradiance had a higher respiration rate and light compensation point, and their
photosynthesis saturated at higher irradiance, than did those grown at low irradiance;
leaves grown at high irradiance had the highest respiration rate and light compensation
point, and their photosynthesis saturated at the highest irradiance. These findings suggested
that leaves acclimated to each irradiance level are those best adapted to that level,
insofar as they appear to have the highest rate of leaf photosynthesis under those conditions.
http://www.mathdotcom.org/notes08/adapatation to sun and shade.pdf

Click to expand...

-Through same mechanism ,flowering / maturing ,may be retarded severely in some species / variations ( aka " strains " ) ,specially regarding Short Day Plants ....

-Well ,yes ,deep red is more efficient ( photon number -wise ) than lower wl reds ( just about 5 % more , though..) ,but regarding PS of upper leaves...

So regarding Photosynthesis using solely 650-680 nm reds ...
Yes,it is the most productive light wls of all others ,but under strict limitations:
-True for upper leaves ,mainly....
-C4 plants utilise those red wls ,better than C3 ..
-Plants (their leaves )get adapted to expect high irradiances..Under low/mid irradiances ,things are quite different...
-Some Blue at region 420-440 nm is needed for optimal stomatal conductance,along with those deep reds ( Ch A : 662 nm - 430 nm )


As for the lower red wls ...
600-640 nm ....

-They have a more "natural day " phytochrome action ..
Thus " mild " photomorphogenic responces from that red wls...

-Cause Ch B is more abundant / activated in older /shaded leaves ( most in numbers ) ,it seems
those " mild " reds ,are quite efficient throughout the whole canopy...
At least ,up to where they "reach "...

- Plants remain productive in low/mid irradiances ..(no so strong "sun adaptance" ).

-Ch B ,is activated by wider range of wls...
Ch B is also more efficient in blue light photosynthesis,than Ch A...

-Optimal stomatal conductance is achieved,a bit more more easily ,than deep reds...


Now,it's about time to ,take into account the green & Far red ,Emerson Effects,Shade Avoidance ,opposite action towards reds,ect....
..

Either a plant is "treated " to expect high irradiances-and mainly utilise it's top part of canopy- ..
Or "treated" ( through a "weird " light quality "starvation" ) to take advantage of every little photon possible...
So to be productive in low/mid irradiances ,provided even from cheapest ,crappiest leds possible....

Giv'em all the "goodies"and you won't get much in return ...
(You will,eventually,as long as they get massive amounts of light power ....)
Starv'em a bit and then they really fight for better production ,even with less power....

I tried to explain this really complicated issue, as simplistic as possible...
It is not that simple,though...

Lots of different factors in between ..

But the main "outline" goes like that,as described above...

( Astir panels are solid proof of what is claimed here,I guess...
With:
-1 watt chips..
-No power concentrating lenses..
-No 650-680 actinics..
-Not the best quality of leds ,there..But cheap enough,though..
- And last but not least,the use of mainly white leds..
Against all odds..
But...
There are no signs of light deprivation,as Psuagro noted...
On the contrary...
Some _including myshelf _are reporting "light damage ",if panels too close to canopy
and/or if Neutrals in excess...
Either leaf edge canoeing or bronze chemical -like "burn" spots ,on some leaves ,under certain panels...
Probably of too much blue, " boiling" the leaves ,
or Ch B over-accumulation,making existing irradiances ,
too much for the plant to handle,if panels are pretty close to canopy..
Moreover, overall plant biomass production seems really more than expected, for the total Wattage used...)

Towards the end of 26th day....
..

The Maximum Quantum Yield for CO2 Fixation and the
Importance of Enhancement Effects
The absolute maximum quantum yield for CO2 fixation or O2
evolution has been a subject of debate for a long time (Govindjee,
1999). We found a maximum quantum yield of 0.093 CO2 fixed
per absorbed photon for the sunlight spectrum– and blue light
grown–leaves at 620 to 640 nm.....

Click to expand...

Nothing about 660 nm light there....( 2012 research ..)
http://www.plantcell.org/content/24/5/1921.full.pdf

Chlorophyll b is a form of chlorophyll. Chlorophyll b helps in photosynthesis by absorbing light energy. It is more soluble than chlorophyll a in polar solvents because of its carbonyl group. Its color is yellow, and it primarily absorbs blue light.[SUP][1][/SUP]

In land plants, the light harvesting antennae around photosystem II contain the majority of chlorophyll b. Hence, in 'shade adapted chloroplasts', which have an increased ratio of Photosystem II to Photosystem I, there is a lower ratio of chlorophyll a to chlorophyll b (Kitajima and Hogan 2003). This is adaptive as increasing chlorophyll b increases the range of wavelengths absorbed by the shade chloroplasts.

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

Click to expand...

The last article you posted proves that the blue and sun light has a HIGHER chl A to B ratio than using red light. They did not test 660nm light and just took prior research from 1987 (the newest) that 620-640nm red is best for growth. "Red light (600 to 640 nm) has the highest quantum yield, whereas blue and green light (400 to 570 nm) are considerably less efficient in driving photosynthesis (McCree, 1972b; Inada, 1976; Evans, 1987)."

The next thing to talk about is the "fact" that Cannabis is a C3 plant. Greg Green, Julie Holland M.D., and many other authors and researches seem to think that cannabis is a C4 plant or possibly even a unique CAM, C3, C4 hybrid. It can use more than 700ppm of CO2, no other C3 plant can do that. They have tested and proven that it does uptake CO2 during dark periods, which C3 plants do not do. Likewise, Cannabis has a very high carbon fixation rate and flowers closer to that of corn and maize then of wheat or rice. All C4 plants are angiosperms, as is cannabis. The stalk of the cannabis plant has a internal structure very similar to that of CAM plants.

You seem to jump around a bit in your conclusions about red light and how useless it is and then when talking about C3 plants you quote text stating that C3 plants need 60-70% red rays. You state that Chlorophyll A to B ratio should be lower but quote repeated studies that state A to B ratios in C3 plants is 3:1.

I personnally feel that we need to get an actually study that test CO2 uptake amouts and if there is a CO2 uptake during a dark or light periods (or both). For too long people have taken Gorge's word on things that he has been proven wrong on so many times. (I cannot find any real study that says cannabis is a C3 plant) The only information that cannabis is a C3 is conjecture from people of forums quoting Gorge. He is a great grower and has a lot of knowledge but he has been wrong on a number of other technical things. I believe this is the same. FYI, Greg Green did actually perform test and determined cannabis to be a C4 plant due to dark period CO2 intake.

I forgot to add, the amount of CO2 uptake is directly effected by temperature. Cannabis tends to grow better in temperatures above 25 degrees C (77 F) and 35 C (95 F). [FONT=Helvetica Neue, Helvetica, Arial, sans-serif] According to one study ([/FONT]Temperature response of photosynthesis in different drug and fiber varieties of Cannabis sativa L.)
"In general, a two fold increase in dark respiration with increase in temperature (from 20°C to 40°C) was observed in all the varieties."

This also indicates that cannabis is a C4 plant as they perform better in higher temperatures than C3 plants. http://www.plantphysiol.org/content/54/5/709.full.pdf Confirms this theory. Likewise, Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions, confirms that the higher the temperature and CO2 the higher the photosynthesis of the plant. They concluded that the optimal growth rate occurred at 1500m Mols, 30 degrees C, and up to 750ppm of CO2 (the highest amount they tested) but that water use efficacy dropped as the temperature increased. Photosynthesis continued to increase as temperatures and CO2 levels increased from 30 C and ambient levels up to the test maxim of 40 C and 750ppm. "The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ∼1500 μmol [FONT=Helvetica Neue, Helvetica, Arial, sans-serif]m−2s−1 PPFD. Furthermore, higher PN (photosynthesis), WUE (water use efficiency) and nearly constant Ci/Ca ([/FONT]intercellular CO2 concentration/ambient CO2 concentration) [FONT=Helvetica Neue, Helvetica, Arial, sans-serif]ratio under elevated CO2 concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO2 rich environment."[/FONT]

There are several other studies that have concluded that to increase CO2 intake requires and temperature increase of 1 degree C per 250ppm. This drier, CO2 enriched environment indicates a C4 plant.

Cannabis grows best at the high end temperature range of the C3 plants and the lower range for C4 plants. Uses higher concentrations of CO2 than C3 plants. Grows readily in nearly every environment in the world. There is a possibility that it may be a C3 C4 intermediary plant.

[h=1]Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO[SUB]2[/SUB] conditions[/h]

http://link.springer.com/article/10.1007/s12298-008-0027-x

C3 for me

Well,brother Hosebomber,that is a very interesting point of view.. (or theory )
I can't argue with what you 've posted...
On the contrary...I've to agree,in some points....
Though some other points ,are really ...confusing ,I should say ?
Hard to swallow,in a way....

If ,indeed ,cannabis plant is a C4 or a " hybrid" C3-C4-CAM plant....
( I do not know for sure,myshelf...Never tested that ,to be honest...
Always took for granted,what was believed -not only from Jorge C. -,that mj is a C3 plant..)
Then the whole thing changes a lot...
Thanx for mentioning that,anyway...

"You seem to jump around a bit in your conclusions about red light and how useless it is.."
You probably have misunderstood what I've writen...
Never claimed that red is useless...On the contrary..

But I 've to make couple of points,here...

I'm finding difficult to trust ,that all cannabis species ( Ruderalis-Indica-Sativa ) are indeed C4 -CAM plants (or that they possess hybrid Carbon Fixation procedures..)
And that,because ,I cannot neglect that Cannabis is a really old species of plants...
C4-CaM plants ,are usually ,latest evolved plants ( C4 plants are approx 3 % of all Earth plant species ..)


Moreover ,natural habitats of Ruderalis & Indicas ,do not justify them to be C4 plants...

But still,what is claimed from you ,might have a good chance to be true...
Regarding Sativas....
And that,if only we accept that the " evolution line " was -from oldest to newest evolved- Ruderalis=>Indica=>Sativa....
Which ,has a really great possibility to be true !

Cannabis plant ,was really ,direct related with Human Species.
Human Species ,as expanded throughout the planet ,carried useful plants along with 'em...
-That is a rather logical explanation ,of cannabis,being one of the most geographical widespread species -
As Cannabis plant was translocated to warmer climates ,of course it adapted to them...

Having in mind that ,almost all of C4 plants are mainly located around tropical & Sub-tropical regions of the planet,indeed Sativa Varieties ,might be ...C4 plants...Or "hybrids"..
(And yes,then what you,amongst others,claim is totally right...)

Cause higher CO2 assimilation is occuring in this regions,as well as high temps,great nutritional antagonism,ect..

The evolution and advantages of the C[SUB]4[/SUB] pathway

Further information: Evolutionary history of plants#Evolution of photosynthetic pathways
C[SUB]4[/SUB] plants have a competitive advantage over plants possessing the more common C[SUB]3[/SUB] carbon fixation pathway under conditions of drought, high temperatures, and nitrogen or CO[SUB]2[/SUB] limitation. When grown in the same environment, at 30°C, C[SUB]3[/SUB] grasses lose approximately 833 molecules of water per CO[SUB]2[/SUB] molecule that is fixed, whereas C[SUB]4[/SUB] grasses lose only 277 water molecules per CO[SUB]2[/SUB] molecule fixed. This increased water use efficiency of C[SUB]4[/SUB] grasses means that soil moisture is conserved, allowing them to grow for longer in arid environments.[SUP][9][/SUP]
C[SUB]4[/SUB] carbon fixation has evolved on up to 40 independent occasions in different families of plants, making it a prime example of convergent evolution.[SUP][10][/SUP] C[SUB]4[/SUB] plants arose around 25 to 32 million years ago[SUP][10][/SUP] during the Oligocene (precisely when is difficult to determine) and did not become ecologically significant until around 6 to 7 million years ago, in the Miocene Period.[SUP][10][/SUP] C[SUB]4[/SUB] metabolism originated when grasses migrated from the shady forest undercanopy to more open environments,[SUP][11][/SUP] where the high sunlight gave it an advantage over the C[SUB]3[/SUB] pathway.[SUP][12][/SUP] Drought was not necessary for its innovation; rather, the increased resistance to water stress was a by-product of the pathway and allowed C[SUB]4[/SUB] plants to more readily colonise arid environments.[SUP][12][/SUP]
Today, C[SUB]4[/SUB] plants represent about 5% of Earth's plant biomass and 3% of its known plant species.[SUP][13][/SUP][SUP][9][/SUP] Despite this scarcity, they account for about 30% of terrestrial carbon fixation.[SUP][10][/SUP] Increasing the proportion of C4 plants on earth could assist biosequestration of CO[SUB]2[/SUB] and represent an important climate change avoidance strategy. Present-day C[SUB]4[/SUB] plants are concentrated in the tropics and subtropics (below latitudes of 45°) where the high air temperature contributes to higher possible levels of oxygenase activity by RuBisCO, which increases rates of photorespiration in C[SUB]3[/SUB] plants.

From Wikipedia...

Click to expand...

Still...
We cannot claim for sure that all cannabis species are definately C4 plants or "Crbon Fixation hybrids "....
Most logical thing to imagine is ,since Ruderalis,Indicas & Sativas,do possess interexchangeable genomes,as they can breed with each other-giving as a result ,thousands of hybrids-,then probably the statement of cannabis hybrids possesing hybrid Carbon Fixation pathways ,might actually be true...
Further investigating is probably needed...

But,this does not justify completely ,that deep reds (650-680 nm ) ,are the ones needed for massive flower production...
Sativas ,which already get irradiated -at their nat.habitats -with lots of deep red wls ,do not possess massive flowering abilities...
What they possess ,is the ability ,to outgrow easily ,antagonistic plants....
Another kind of "productivity"...

Personal experiments ,at least,showed ,that the net photosynthetic ratios,at low/mid irradiances,where greater( slightly ) when using 620-640 nm reds ,than 650-680 nm ones...
While ,Phytochrome ratio response ,had a rather big difference ,between those two bands of reds...
Meaning ,that while 620-640 reds performed great (always in low/mid irradiances) in most plants tested (mj was amongst them ),650-680 nm reds ,did have some weird adverse effects on many of them...(in some variations/strains of mj ,also...)

Moreover, mainly Warm White leds ,do contain a portion of those deep red wls...
What I'm claiming here,is that adding ,way too much 650-680 nm reds ,
has more photomorphogenic role,than a photosynthetic one...

And ,while it probably stands true that some ( Sativa genome dominant ? ) variations do grow well under those reds,others don't....
While with 620-640 nm ,there is not such a " problem"...

I 've yet to see ,a research that claims 660 nm reds are superior to 640nm reds ,regarding PS,in an extend ,that would justify the utilisation of only 660-680 red leds...
Differences in net PS rates ,are rather small,with 620-640 nm reds , covering the needs of a wide range of plants...
Something that for 650-680 nm reds ,does not stand true...

If still mj is a C3-C4 intermediary plant,that doesn't automatically means ,that 660-680 nm reds are safe in large doses ,or that they are more efficient ( PS -wise ) than lower wls of reds...

For sure ,regarding some strains ,they do have a " boost" effect ,at rather conservative doses ...
While for other strains,they can mess things up ,pretty easily..
( Way too much Sun Adaptation, unearthy Phytochrome ratios,ect..)..

Again...
Astir panels ,are solid proof of that.....
Not high power leds there,not 650-680 actinics there and no lenses ...
But still,they are doing the job ,just fine I should say...
Don't you think so ?

I've seen same or better results with Blue/red combos ,using 660 nm reds...
But the overall powers were much higher/greater*, concentrating lenses were used,high quality leds were used also,ect....
Comparing to those and their implemented " theories" ,Astir led panels should not have been able to grow ,not even the simplest of leafy "greens"..
Which up till now ,is not a case,at all...

Edit:
*With couple of "bright" exceptions..
i.e Han's latest panel,which uses few only 660 nm reds ...
And of course Guod's panels ,which even at low powers ,and with plenty of 660 reds,do work
fantastic ,even at lower irradiances ...
(That makes them unique ,I guess... )..
Guod,has made a really fine job there...
Extraordinary panels ...
And high quality ones....

Hope you'll go to the dark side (IC) and check out my new photos...

What a difference ONE week makes. I was barely seeing what I hoped to be pistil clusters. I think increasing the V+B ppms from 600 to 800, and now 900 was key. It's not so much the ppm, but what that ppm consists of - more N than most think is good + a bit more P, but manly more K.

Daily bud growth is exciting now. I pollinated one branch of 3/4 plants, as I love them for different reasons

HOT5

Picture 1 is the smallest. She has zero branches, so I pollinated a small cola. She is ~ 14" tall, perfect for a SOG grow. A whole bunch of big mj dicks (well dickettes) would look cool

LED + Reptile Bulbs

She is getting crazy sexy. 3 clones from her are in the lower left of that photo

PetFlora said:

- Through Photomorphogenesis and phytochrome action ( Low Pr / Pfr ratios ),plants illuminated with 650-680 nm red become sun adapted.
That means ,that they need quite high total irradiances to produce...(Many Watts of leds .... )

Kind of ambiguous, no? What does many watts mean; 1:10, 1:20, 1:50...?

Click to expand...

Not so ambiguous as it may seem....

Well ,as it is widely supported up till now,a daily average irradiance of 26 mol m[SUP]-2[/SUP] day[SUP]-1[/SUP] will effectively grow most species of higher plants.

26 mol = 26 * 10[SUP]6[/SUP] umols ....1 Day = 24 hours x 3600 sec/hour= 86.400 sec ....

26 mol m-2 day-1 = 26 *10[SUP]6[/SUP] / 86.400 =300.1 umol sec[SUP]-1[/SUP] m[SUP]-2 [/SUP]for 24/0 cycle or 600 umol sec[SUP]-1[/SUP] m[SUP]-2
[/SUP] for 12/12 cycle.....

If plants are "shade " adapted
( Leveled canopy , horizontaly oriented thin & large leaves with long leaf stems ,lots of Ch B ,more active PS II,dense branching ,ect ),
then they need smaller irradiances for effective growth...
As they'll have:Low compensation point=In simple words they start producing with low ambient light irradiances
At the compensation point, the rate of photosynthesis is balanced to the rate of respiration.
Products of photosynthesis are used up in respiration so that the plant is neither consuming nor building biomass
But,also...
Lower Photosynthetic Light Saturation Point,also=They do not tolerate high irradiances...
Something which may prove a "pro" rather than a "con",regarding the constant & stable irradiances of artificial lighting ,
at controlled enviroment sites...Take into account ,also the prolonged periods of illumination -i.e 24/0 or 18 / 6 ..
Also,3-5-10 ect Watt leds and narrow beam lenses ,at this case ,are not only meaningless ,
but can have deleterious effects on plants....

If "sun" adapted
(layered canopy, angled thick & small leaves close to stem,sparse branching,High Ch A / Ch B ratios,more active PS I ,ect.),
they need more power/energy...(Sun light at sea level (noon )=700-2000 umol sec[SUP]-1[/SUP] m[SUP]-2[/SUP] )As they'll have:Higher compensation point=In simple words they need more light ,to produce...
Higher Photosynthetic Light Saturation Point,also=They tolerate more light ....

....

Depending on led efficiency (.ie. for whites = .3 up to .45-.5,nowdays ) and spectrum config ,
one can estimate total Watts needed...
....
Actinics do work,but in rather high irradiances....
(Especially if there's enough "unleashed" 650-680 nm red light ,there...)
While with some "specialised" white light ,plants can produce with lower irradiances...

As for flowering...(At the case of whites )
Time....
Time is needed ...
So ....Not in particular need for much FR light there...
(where actinics should benefit from FR ....)

Energy = Power * Time .

Same amount of energy can be harvested by plants during total flowering period , either :
-By using relatively high power of actinics(with some FR amongst them for extra Pfr=shorten the otherwise long, maturing time..) and relatively normal to short total flowerin period ..
Or....
-By utilising lower power of whites and a relatively extended* flowering / maturing period....
(*Which already happens with white leds ,anyhow...)