Dual Spectrum Lighting?.

Ill chime in here. I like to get as close to natural light as I can, and my plants seem to love it. I like the dual arc HID's. The MH has a high CRI and I can blend or fine tune the action spectrum for my preference. HPS on the other hand has a very low CRI and is hard to blend. When you get as close to natural light the appearance is white light and that's critical for proper plant development by means of secondary pigmentation and carotenoids.

Plants sense dominance in spectrum wavelength(PAR) by use of the phytochrome and responds as deemed appropriate. However plants are also photoperiodic and regardless of actual color temperature will transition into a reproductive phase once mature. Red dominance helps accentuate the bloom phase however each wavelength has it's own affect on plant photosynthesis and growth response.

I have found that:
6500-7500k is great for veg @ 20/4
4500-5000K is great for transition to bloom (last week of veg, into first 2 weeks bloom) @ 15/9 tapering to 12/12
3000K is great full bloom
10000K as a finisher the last 1/2 week of bloom @ 24/7

tikitoker said:

Ill chime in here. I like to get as close to natural light as I can, and my plants seem to love it. I like the dual arc HID's. The MH has a high CRI and I can blend or fine tune the action spectrum for my preference. HPS on the other hand has a very low CRI and is hard to blend. When you get as close to natural light the appearance is white light and that's critical for proper plant development by means of secondary pigmentation and carotenoids.

Plants sense dominance in spectrum wavelength(PAR) by use of the phytochrome and responds as deemed appropriate. However plants are also photoperiodic and regardless of actual color temperature will transition into a reproductive phase once mature. Red dominance helps accentuate the bloom phase however each wavelength has it's own affect on plant photosynthesis and growth response.

I have found that:
6500-7500k is great for veg @ 20/4
4500-5000K is great for transition to bloom (last week of veg, into first 2 weeks bloom) @ 15/9 tapering to 12/12
3000K is great full bloom
10000K as a finisher the last 1/2 week of bloom @ 24/7

Click to expand...

Thank you for this, great info here.

The dimensions of my flower room make it almost impractical to be using 2 separate ballasted units. The plants would not be able to simultaneously share both spectrums.

It's perfect for using 2 MH or HPS, but not one of each unless I continually move them.

With this in mind, if given a choice would you?

A. Use a 600 HPS dead center and surround with additional 6500K lighting.
Or
B. Use the 600 MH dead center and surround with 2700K lighting.

BTW, I also supplement with 360W of straight UV/B lighting...2 spotlights.

Thanks again for your assistance.

A. also including the optional uv but uv has to be on short interval timer due to power factor

thank you and GL!

Effect of light on Growth and Development
[SIZE=+0]-Light quality and quantity are the most significant environmental factors affecting plant development.[/SIZE]
[SIZE=+0]-Light induces dramatic changes in morphology and biochemical (protein) composition.[/SIZE]
[SIZE=+0]How does light induce such changes? e.g. increase in rubisco, LHC[/SIZE]
[SIZE=+0]A Simple Model of Signal-induced Responses[/SIZE]
[SIZE=+0]1. Signal perception by a receptor[/SIZE]
[SIZE=+0]2. Signal transduction[/SIZE]
[SIZE=+0] a) Communcate signal to other cell parts[/SIZE]
[SIZE=+0] b) Amplify the signal[/SIZE]
[SIZE=+0] c) Network and cross-talk[/SIZE]
[SIZE=+0]3. Primary response[/SIZE]
a) Increase or decrease in gene expression
[SIZE=+0] b) Change from inactive protein ---> active protein
4. Physiological or cellular response.[/SIZE]
[SIZE=+0]Plants have 3 types of Photoreceptors[/SIZE]
[SIZE=+0]1. Phytochrome 660 /730 nm[/SIZE]
[SIZE=+0]2. Blue light receptor 400-500 nm[/SIZE]
[SIZE=+0]3. UV-B Receptors 260-350 nm[/SIZE]
[SIZE=+0]Phytochrome plays a critical role in every stage of development.[/SIZE]
e.g. seed germination (lettuce)
Different Intensities of light induce different responses
a. Very low fluence (VLF) response :
b. Low fluence (LF) responses
c. High irradiation reactions (HIR)
[SIZE=+1]I. PHYTOCHROME [/SIZE][SIZE=+0]: A red light receptor[/SIZE]
[SIZE=+0]Absorbs in the Red 660 nm, Red induces change[/SIZE]
[SIZE=+0]Absorption in the Far red 730 nm reverses it.[/SIZE]
[SIZE=+0]Red light causes many changes: e.g.[/SIZE]
[SIZE=+0]Seed germination[/SIZE]
[SIZE=+0] Inhibition of stem elongation[/SIZE]
[SIZE=+0] Leaf expansion[/SIZE]
[SIZE=+0]Present in all tissues:[/SIZE]
[SIZE=+0] Roots, Shoots, Leaves[/SIZE]
Phy is found in the nucleus and cytoplasm, and it is not embedded in the membrane.
[SIZE=+0]1. CHEMISTRY[/SIZE]
[SIZE=+0]Chromophore is attached to a protein of 124 kD.[/SIZE]
[SIZE=+0]Phy has two interconvertible states.[/SIZE]
[SIZE=+0]Pr ----RED LIGHT ---> Pfr ---> ---> ----> RESPONSE[/SIZE]
[SIZE=+0] <---FAR RED -------[/SIZE]
[SIZE=+0] <---DARK ----------[/SIZE]
[SIZE=+0]Stable Unstable (Degraded)[/SIZE]
[SIZE=+0]Inact. Active[/SIZE]
[SIZE=+0]2. PHYTOCHROME acts as a light-activated switch.[/SIZE]
[SIZE=+0]A unique trait of phytochrome-regulated response is PHOTOREVERSIBILITY.[/SIZE]
Three kinds of phytochrome responses:
VLF, 1-100 nmol/m[SUP]2[/SUP] Not reversible
LF, 1-100 umol/m[SUP]2[/SUP] Reversible
HIR 10 mmol/m[SUP]2[/SUP] Not reversible
Phytochrome can sense light changes during the day
-photon density (quantity)
- Ratio of Pr/Pfr (quality)
[SIZE=+0]Multiple forms of phytochrome[/SIZE]
Phy A: labile form, present in dark grown seedlings
Phy B, C, D, E: stable form found in green seedlings and plant.
[SIZE=+0]3. How is a light signal transduced to give a response?[/SIZE]
[SIZE=+0]a. Physiology and cell biol. approaches : electrical potential, [Ca] changes[/SIZE]
[SIZE=+0]b. Biochemical approaches: enzyme activity changes[/SIZE]
[SIZE=+0]c. Molecular methods:[/SIZE] changes in gene expression (mRNA)
[SIZE=+0]d. Genetic approach (v. powerful): find mutants that fail to respond to signal
Identify gene product to deduce its role in signaling[/SIZE]
[SIZE=+0]Models: mode of Action[/SIZE]
[SIZE=+0]1. Regulate ion transport[/SIZE]
[SIZE=+0]2. Regulate gene expression[/SIZE]
Early response genes
Late response genes
3. Regulate metabolic pathway
4. Change cytoskeleton
[SIZE=+1]II. Blue Light-induced Responses[/SIZE]
1. Responses are triggered by light of 450 nm.
e.g. phototropism, inhibition of hypocotyl elongation, induction of stomatal opening
2. Several blue-light receptors have been identified. Receptors affect different responses.
a. Cryptochrome or Cry1 inhibit stem elongation
b. Cry2 cotyledon expansion, clock, flower induction
c. Nph1 at the PM = Phot1 (phototropin1) phototropism
d. Npl 1= Phot2 chloroplast- high light avoidance
e. Flavin
f. Carotenoids
3. How is a Blue light signal received and transduced? Mode of Action:
Many responses are regulated by both Red and blue light.
1. Signal Perception by a Receptor
2. Second messengers transduce and amplify the signal
3. Final Responses
a. Regulate Activity of a Membrane Transporter:
e.g. H+ pump activated, or Anion channel opens
b. Activation/repression of Gene expression through proteins interacting with light-regulated elements Crytochromes found in the retina of mammals have a role in circadian rhythm.

I run two 600w HPS in my flower room supplemented by 6-8 vertical hanging 125watt 6500k CFL's and am really pleased with the results I can really sneak those CFL's in close down through the upper canopy and along the sides. I definitely noticed the plants like the extra light but I have no way of knowing if it is the dual spectrum or just the additional light. I think it is both IMO.