Is 6500k good enough? - Orchid Board

m_ms09 · #1 03-25-2008, 11:55 AM

My 6500k cfl light just died, so now I must get a replacement!

What are the advantages of using a 6500k light as opposed to something else for growing in a viv???

Orchidophile · #2 03-25-2008, 12:02 PM

I use a 6700k quad tube on mine and it works great, every thing is growing fast.

Ross · #3 03-25-2008, 12:02 PM

The higher the K number, the bluer the color of the light. Plants need both the red end for spike development and the blue end for vegetative growth. There are specific color temperature needs, but if you can only use one bulb, try for a "full spectrum" bulb that provides light at both ends of the spectrum as well as middle of the spectrum for esthetics (plants don't need very much in middle, but humans see better color rendition in middle range.)

Try this company to see if you can get a "full spectrum" replacement 2 to 200 Watt Compact Fluorescent Bulbs : 1000Bulbs.com The Light Bulb Superstore.

Daemos · #4 03-25-2008, 01:13 PM

CFL's are doing just great. As long as you use full spectrum light of at least 5600K you will get rapid growth. In principle the K value doens't matter too much if you look at the emission spectra charts. Its just that lower K values give higher emission peaks at the red wavelenghts. If you go for full spectrum bulbs you will get the light you need to get your plants growing.

In fact, I did some crazy experiments on plants like putting them under normal light bulbs or just UV blacklights and growing was also achieved. Nothing beats full spectrum though.

Magnus A · #5 03-25-2008, 03:59 PM

The important thing is that the light is full spectrum. If so, it contains more or less all wave lenght.

And for red and blue light versus growth or spiking...... Everything the plant is absorbing is going through the photosystem I and II. The NADPH and ATP produced has NO memory of what wavelenght hit the plant. The plant uses NADHP and ATP to "fuel" the growth and spiking not the light!
That was the scientist in me! The orchidgrower is more confused.......
I get the feeling that the suns UV light do something to for example rupicolous Laelia´s and Sophronitis to trigger bud formation. The protection mechanism in the plant for UV-radiation may produce something initiating bud formation but this is not investigated on basic level. And this should then contradict Ross statement that red light is needed for bud formation? ????

So Ross, do you have the references for the study of red and blue light or is it just hobbygrowers trials you refere to or. Would be very interesting to read as I have a professional interest as an assistant professor in molecular biomimetics.

/Magnus

m_ms09 · #6 03-25-2008, 05:49 PM

Quote:

Originally Posted by Magnus A

The important thing is that the light is full spectrum. If so, it contains more or less all wave lenght.

And for red and blue light versus growth or spiking...... Everything the plant is absorbing is going through the photosystem I and II. The NADPH and ATP produced has NO memory of what wavelenght hit the plant. The plant uses NADHP and ATP to "fuel" the growth and spiking not the light!
That was the scientist in me! The orchidgrower is more confused.......
I get the feeling that the suns UV light do something to for example rupicolous Laelia´s and Sophronitis to trigger bud formation. The protection mechanism in the plant for UV-radiation may produce something initiating bud formation but this is not investigated on basic level. And this should then contradict Ross statement that red light is needed for bud formation? ????

So Ross, do you have the references for the study of red and blue light or is it just hobbygrowers trials you refere to or. Would be very interesting to read as I have a professional interest as an assistant professor in molecular biomimetics.

/Magnus

I was under the impression that photosystem I and II require a certain wavelength of light in order to be excited, per se, and release electrons which are then used for photorespiration? Obviously they won't have a "recollection" of what light had hit it, but I believe that it has to be of a certain wavelength. For some reason, something around 700nm seems to be popping into my head. Yep, I was close, apparently photosystem I requires 700nm and II requires 680nm (I'd like to thank wikipedia...).
Anyways, I'm no botanist, or expert on the Calvin Cycle, but I do like me some molecular genetics! hahaha

Thanks for taking the time to post!

Magnus A · #7 03-26-2008, 07:09 AM

Quote:

Originally Posted by m_ms09

Yep, I was close, apparently photosystem I requires 700nm and II requires 680nm (I'd like to thank wikipedia...).

m_ms09, this statement is somewhat wrong. It is correct that the P680, the central part in photosystem II (PS II) has the absorbing maximum at 680 nm BUT it is not the primary absorber in plants. Attached to photosystem II is an antenna system that collect the sunlight and direct the energy (not light) to the chlorofyll (P680) in PS II.
It is this antenna system that is interesting in a light discussion not the central part of PSII. Unfortunate, this is very often omitted outside the scientific community

The same is valid for photosystem I, it also has an antenna system that collects the light.

/Magnus

m_ms09 · #8 03-27-2008, 02:05 PM

Quote:

Originally Posted by Magnus A

m_ms09, this statement is somewhat wrong. It is correct that the P680, the central part in photosystem II (PS II) has the absorbing maximum at 680 nm BUT it is not the primary absorber in plants. Attached to photosystem II is an antenna system that collect the sunlight and direct the energy (not light) to the chlorofyll (P680) in PS II.
It is this antenna system that is interesting in a light discussion not the central part of PSII. Unfortunate, this is very often omitted outside the scientific community

The same is valid for photosystem I, it also has an antenna system that collects the light.

/Magnus

Unfortunately we never went into that much detail way back when I learned about photosystems, but it's refreshing that you know so much!!

Thanks for taking the time to explain all of that!

Ross · #9 03-25-2008, 04:17 PM

Magnus, I don't (personally) worry about that stuff. There have been several discussions under the "growing under lights" forum discussing this. As I recommended to the original poster, I recommend "full spectrum" as did you. While it may seem wasteful to some folks to provide more than the plant actually requires, the red/blue solution looks weird to me. All of my lights are either full spectrum (CF) bulbs or a balance of t5 straight tubes mixed to provide a K balance of approx 5000Kelvin. This is because the Kelvin reading of full sun at the equator on a clear day is approx 5000K (actually about 5500K) and most "daylight" films are color balanced for 5000K. I personally like the color rendition at 5000K - just my opinion. Good response Magnus. Here's a few links to get you started.

Affect of artificial light on Orchids

http://www.orchidboard.com/community...rray-here.html

http://www.orchidboard.com/community...ext-setup.html

Royal · #10 03-25-2008, 05:07 PM

I'm no professor, but Ross' advice is good. You might be able grow and flower some plants under light from only one end of the spectrum or the other. You might find that certain species thrive better in one over the other. You might be able to put on new growth under a UV blacklight, as did Daemos. You might be able to flower orchids under a traffic light! If a light photon is a light photon, there shouldn't be any difference as long as the lumen output is there. You don't see too many people using cool white fluorescents, or for that matter traffic lights to grow plants, do you?

Your best bet is 5000K or "full spectrum." This will provide a variety of "color" or wavelengths needed for all of your plants to grow and bloom.