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How To Compare Grow Lights
- Thread starter DrPhoton
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Campesino
Banned
I appreciate the information and insight, but 5 of the 6 rules are "Don'ts"... So it seems that PPF is what it boils down to.
Are there other factors that you would consider?
Would there be differences if the priority was not efficiency (e.g. distribution, quantity or quality of light)?
Are there other factors that you would consider?
Would there be differences if the priority was not efficiency (e.g. distribution, quantity or quality of light)?
DrPhoton
New member
Unfurtunately Photon flux is the main metric for accurately quantifying the total output capacity of a light source. I say unfortunately because it is not typically provided by manufacturers as it would show the underwelming performance of most cheap fixtures today. As such they use other quantities and metrics to misguide the consumer in thinking their product is of high quality. Using PPFD maps are good for assessing the distribution uniformity which is always beneficial. However single PPFD on its own is useless, except for knowing the recommended height placement. The quality of light spectrum is really not of big importance, as i have discussed in my other articles, research shows that light quantity is more important than light quality. However making sure there is some amount of blue is beneficial for a better structure for indoor environments. I may add this to the article.
What i would like to add to the response of your question on light quality is about photomorphogenesis. Which is the mediated response of plants to light. Photosynthesis is the main determining factor for energy production, the efficiency of each color spectrum is irrelevant because the quantum yield (photosynthetic efficiency) response is very identical over the photosynthetic bandwidth. With photomorphogenesis, mediated responses from light effects the morphology of plants. I like to think of it as photosynthesis manufactures energy and mediated responses such as photomorphogenesis, thigmomorphogenesis say what is done with that energy. The fact of the matter is that although quality of light can change the morphology of plant, it cannot change the photosynthetic efficiency. It can only indirectly increase the photosynthetic production through capturing more light. Which is why blue is recommended.
That make sense ?
What i would like to add to the response of your question on light quality is about photomorphogenesis. Which is the mediated response of plants to light. Photosynthesis is the main determining factor for energy production, the efficiency of each color spectrum is irrelevant because the quantum yield (photosynthetic efficiency) response is very identical over the photosynthetic bandwidth. With photomorphogenesis, mediated responses from light effects the morphology of plants. I like to think of it as photosynthesis manufactures energy and mediated responses such as photomorphogenesis, thigmomorphogenesis say what is done with that energy. The fact of the matter is that although quality of light can change the morphology of plant, it cannot change the photosynthetic efficiency. It can only indirectly increase the photosynthetic production through capturing more light. Which is why blue is recommended.
That make sense ?
Campesino
Banned
Yeah...but it raises a question
Seems that you are primarily concerned with photosynthesis and light/energy efficiency. Do you not think that photomorphogenesis is important in directing energy to flowers vs veg growth? I understand that the laws of thermodynamics apply, and total energy limits photosynthetic activity. But we aren't just interested in growing biomass, we are primarily interested in growing flowers. Therefore, I feel like those processes that direct the allocation of growth are really important to consider.
Seems that you are primarily concerned with photosynthesis and light/energy efficiency. Do you not think that photomorphogenesis is important in directing energy to flowers vs veg growth? I understand that the laws of thermodynamics apply, and total energy limits photosynthetic activity. But we aren't just interested in growing biomass, we are primarily interested in growing flowers. Therefore, I feel like those processes that direct the allocation of growth are really important to consider.
DrPhoton
New member
Light and photosynthetic efficiency is what directly drives energy and growth. Although photomorphogenesis has an effect of what is done with that energy, this is really only applicable to plants in vegetation. Once the plant has reached flower induction, photomorphogenesis has no effect on flower morphology as the developement of the flower is already being prioritized, all source energy is being directed to sink locations (flowers). How that energy is used is not defined by the quality of light. Although there is the exception of trichome development, however this is a seperate variable. Which is not fully investigated yet.
From a section of a book i have read on photomorphogesis by hans mohr.
"The characteristics of the flowers (including stamens, pistils, corolla and calyx) are hardly modified by light. A potato plant will form very similar flowers under all circumstances which allow flower formation at all."
The various physiological effects of light mediating photoreceptors have been wonderfully characterised over the decades, none of which are linked to floral morphology.
From a section of a book i have read on photomorphogesis by hans mohr.
"The characteristics of the flowers (including stamens, pistils, corolla and calyx) are hardly modified by light. A potato plant will form very similar flowers under all circumstances which allow flower formation at all."
The various physiological effects of light mediating photoreceptors have been wonderfully characterised over the decades, none of which are linked to floral morphology.
DrPhoton
New member
I like ceramic metal halide, although i do have sodium discharge. LED is good if the right product is chosen, eventually LED will be the dominant form of all lighting technologies.
What lighting technology is best for you depends, each provide some unique quality that suits the individual user differently. So theres not exactly one technology that is the best.
Perhaps you might want to look at my grow lighting technologies article.
What lighting technology is best for you depends, each provide some unique quality that suits the individual user differently. So theres not exactly one technology that is the best.
Perhaps you might want to look at my grow lighting technologies article.
oldjarhead100
New member
My head hurts and its to early to digest all that lol good write up Danger Dan
Vajipozezo
New member
Thanks for the detailed clarification. I need to calculate the PPFD for my 1000 watt led grow light. For the 5 meter ceiling mounting, the value is about 500.
But I have a doubt on whether or not we should use monochromatic or full spectrum for grow light purpose. I know it is very controversial. It is because photosynthesis is very sensitive to specific wavelength. And thus some led lighting manufacturer will produce orange or purple lights for grow room. However, other supplier suggests the use of full spectrum...
But I have a doubt on whether or not we should use monochromatic or full spectrum for grow light purpose. I know it is very controversial. It is because photosynthesis is very sensitive to specific wavelength. And thus some led lighting manufacturer will produce orange or purple lights for grow room. However, other supplier suggests the use of full spectrum...
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oldjarhead100
New member
I put a 1000 w hps and 8 100 w led light bars with 2 of kinds micro lights for bloom ,I think that covered the spectrum
Ok. So lets say the light claims to be a 400 watt hps equivalent. Pulls 214 watts from the wall. Total ppf is 470 Umols/sec, efficiency ppf/watt is 2.2 umols/watt and total ppfd is 430 umols/m2/sec. That's the information we should be looking at? Also, with total ppf @470 and ppfd @ 430, those are the numbers that back up the claim it's a 400 watt hps equivalent?
And then there's color temperature. For a full spectrum light, veg to flower 3500 seems to be average, I think, but if you go lower its better for flower and higher is better for veg, yes?
And then there's color temperature. For a full spectrum light, veg to flower 3500 seems to be average, I think, but if you go lower its better for flower and higher is better for veg, yes?