sientbob

Absolutley.However, evolution has already taken place so if the plant only used specific wavelengths much of the light energy from the sun would be lost to photosynthesis because the photons would lack sufficient energy to drive the reactions. So it turns out the the reaction center pigments, P680 and P700, are chlorophyll pigments absorbing light maximally at 680 and 700 nanometers...in the low-energy red-end of the visible spectrum. Of course if plants could only absorb 680 and 700 nanometer light, they would be missing a lot of light. So evolution has provided chlorophyll a with a range of other pigments, antenna pigments, that absorb higher-energy wavelengths and pass the absorbed energy on to chlorophyll a. Thus plants can utilize light from every wavelength in the visible spectrum from 400 to 700 nm. This is best observed by examining the action spectrum for a particular plant.




And photosynthesis is not the only light dependant reaction I am trying to cater to in our favorite plant. Plants can sense light direction, quality (wavelength), intensity and periodicity. Light induces phototropism, photomorphogenesis, chloroplast differentiation and various other responses such as flowering and germination.

Light quality is mainly sensed by the presence of different light receptors specific for different wavelengths. The red/far red photoreceptors are called phytochrome. There are at least 2 classes of blue light receptors; cryptochrome recognizes blue, green and UV-A light, while phototropin perceives blue light.

:edit:
Here is an experiment where they grew under 667nm, 737nm, or a combo of the two. It should give you an idea of the improtance of other wavelengths to healthy plants.

read this and tell me what you think

:/edit:

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ogoun

Thanks for the heads up! This clears up a lot for me. The graphs especially.

It was good to note what you said about other optical effects (directionality, period, etc).

Through the understanding of such scientific research and testing, we can all benefit by applying techniques which have a solid basis, rather than relying on "word of mouth" methods which, while occasionally being very effective "how" methods, are sometimes not well understood in the "why" department.

Thanks again,

Pete.

P.S. I read somewhere that many chlorophylls do not use much of the green spectrum (it reflects green), due to it evolving in underwater environments, where the water severely attenuates this spectrum...

penguin

Ho ogoun


The phycobilins (phycocyanin and phycoerythrin) evolved in blue-green algae and red algae. These pigments are not present in terrestrial plants. But the 'horticultural' lamps would seem to be designed specifically for these pigments.


[rant]Why is it that every lamp (even the crappy ones) in the aquarium shop has a SPD on the package, but SPD's are difficult to obtain for so-called horticultural lamps? Maybe if we required SPDs as a condition of sale at the hydro shops, we'd be getting better info - and possibly better lamps? [/rant]

I think it's safe to say that actinic fluoros should play a role in our veg rooms.

[edit]Nice post sientbob , I am still trying to digest the quantum efficiency paper. So far, it seems to provide an explanation for the dramatic difference between yields under optmum and sub-optimal flux density. [/edit]


penguin

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penguin

Ultralux full-spectrum fluoro

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penguin

Given the claims made in the ad copy for this lamp, I am resisting the temptation to take a few potshots.

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Beener

I was a bit indifferent to fluoro's until I saw all the SPD's in this thread. It appears that one can really fine tune their lighting by adding a combo of bulbs to their set-up.

Penguin, I agree. I've been hunting the "Super Actinic R" bulb since you posted the SPD several weeks back. There are a few interesting SPD's here.

However, I am finding it a bit frustrating speaking to light suppliers. If I don't already have complete info in hand, they can't seem point me in a direction. I need to have done my homework first. Then ask if they carry the specific bulb I'm looking for.

Has anyone looked at the Hortilux Blue bulb?


I've decided to hold up on my next grow until I re-examine my set-up (I have some clones to play with in the mean time). At this point, I would like to tighten up all the nuts and bolts first. Then grow larger, less frequent grows.....I'm becoming less patient, I guess.

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Beener

Beener

Haha, never mind. I just scanned back through the thread and saw the Hortilux blue on pg. 1.

It's about time to start rating this thread. It's one of (if not) "the" best lighting thread I've seen here.

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Beener

penguin

I'm still not to enthusiastic about them, they are just too inefficient.

Should be availabe at a decent aquarium shop, they are supposedly the most popular aquarium fluoros.


Tell me about it The aquarium nuts are years ahead of horticulturists in getting lighting providers to give product information that's actually useful. Information available for so-called horticultural lighting is a sham - vendors talking about CRI, CCT, and Lumen output as if these ratings mattered at all is just plain insulting. Further contributing to the confusion surrounding lighitng does a tremendous disservice to the community. Every single hydro shop employee needs to be aked by every single lighting customer about SPD & radiant flux, and direct inquiry to the manufacturer would also help. Stating explicitly that we will not by products without information is the probably the most effective way to get it. [/rant]


It looks very good. I want to try it, but it has not been available at my local hydro shops.


If it's patience you're lacking, you might wish to consider a perpetual harvest?


penguin

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sientbob

Your gonna have to sing a little louder bro. The misconceptions and sales pitches are well ingrained. Although I do hear ya, and the song sounds good.

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until things are brighter I'm the man in black-Johnny Cash
money for nothing

Please read our Posting Guidlines, Grow Guide, and Library of useful threads.
Learn about light? Which lamp to buy? Troubleshooting HID and Fluorescent lamps
Atomospheric Control guide. Fun with ventilation. Fan speed control
Latitude model. Outdoor grow started from cuttings. Adventures in growing Outside.

penguin

As long as we are going for it we might as well request that they do all the work for us and give us a Tazawa PGRE rating.


penguin

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