Manipulatin' her ...

lax123 said:

Hi,
SDS, do you have more input on that?

How?
Do you mean genetically adapt?
From my understanding I would not know how, as i think that would require them to be heavily mutating and also bequeathing those mutations to the next generation.
I think thats highly unprobable, as plants are no haploid bacteria.
Other thing is adaption via epigenetics, -genes get triggered or blocked caused by environmental changes, e.g. light circumstances.
But this would be happening within generation 1.

I think concluding "things" gets quite difficult.
I just looked at the heliospectra link you gave:

So they compare their custom spectrum of 111W to 32W of white led and then say "look our spectrum yielded much more"?
I mean i posted the diagramm hps spectrum vs quantum yield, it clearly showed that hps fits very nicly withing mccree curve, which is the average of like 30 landplants.
And those helios guys put out info telling you the complete opposite.
The plant led selling companies seem to really trying hard to get things not done or are they.



I guess you know the study where they conclude that in "strong white light" added green light can even max out photosynthesis rate more than any additional added red light.
As leaf absorbtion rate for red light is so high, it has the downside that it also gets much faster saturated with it, thats where other wls come into play.
So even the seemingly simple task of just feeding the plant with light isnt just that simple.

I think maxing out photosynthesisrate within a fixed wattage of used power could be more important than minor photomorphogenetical alterations, e.g. that effective intracanopy lightning could have more of an effect then using wether 660 or 630nm.


I wonder how you guys are doing your experimenting e.g. with 660nm.
Do you have side by side comparisons, or have you grown those plants from the same mother for several times and notice the differences by experience?

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(...)Today, Cannabis grows around the world and is, in fact, considered the most widely distributed of all
culti- vated plants, a testimony to the plant's tenacity and adapt- able nature as well as to its usefulness
and economic value. Unlike many plants, Cannabis never lost the ability to flourish without human help
despite, perhaps, six millennia of cultivation(...)

(...)Whenever ecological circumstances permit, the plants readily "escape" cultivation by becoming weedy
and estab- lishing "wild" populations.(...)

(...)Such an adaptable plant, brought to a wide range of environments, and cultivated and bred for a
multitude of products, understandably evolved a great number of dis- tinctive strains or varieties, each
one uniquely suited to local needs and growing conditions. Many of these varieties may be lost through
extinction and hybridization unless a concerted effort is made to preserve them.(...)

(...)Nature also calls on the gene pool to ensure that a strain will
survive. As climate changes and stronger pests and diseases appear, Cannabis evolves new adaptations
and defenses.(...)

Marijuana Botany An Advanced Study:
The Propagation and Breeding of Distinctive Cannabis
by Robert Connell Clarke

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churchhaze said:

If you experiment with LPS, I'd love to see the results. I had the same exact idea about a year or 2 ago. Maybe you got the idea from me?

Here's my theory on the mysterious yellow:

There are 2 ways to think about it.

1) Yellow penetrates, and absorbs decently. Yellow alone causes %Pfr to be decently high. Red absorbs terrifically, and thus has terrible penetration. Red alone causes %Pfr to max out. This means red feeds the top of your plants while yellow feeds the middle. Furthermore, leaves lower down the plant will only see the yellows and far-reds, with all the reds filtered out already. This will cause %Pfr to converge lower than canopy height growth and thus calibrates shade avoidance effect somewhat.

2) What new growth sees as "yellow", the same %Pfr can be obtained with a combination of 660nm and 730nm for 1 layer of growth. Think of how with human vision, you can make yellow from red and green. The same holds true with "phytochrome vision", but this only works for one layer of growth (since the next layer down in the red+far red subjects would have all the red light removed already).

For example, if you have one expanding leaf with LPS light shining on it, you could obtain the same %Pfr that leaf sees using a combination of 660nm and 730nm that gets it to converge at the same %Pfr.

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Positivity said:

Yah there's no doubt mj will grow differently in different environments. Living on an island on the equator you get a pretty high standard for herb. Trying to match that quality indoors takes some manipulating of the light to achieve. Sure it will grow fine with one simple light source, but I doubt it will compete with a plant grown at high elevation near the equator.

using 660nm has proven to me to provide a denser plant than outdoor. Hate to say it, but a nicer aesthetically
bud than outdoor. And also using uv appears to increase the oils in the plant and bring it closer to outdoor quality.

I wouldn't bother manipulating the light if I had the same success using a simpler lighting scheme.

But then again, people's experience varies. I just try and convey what I think correct.

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While issues concerning cannabis have been evaluated many times in the past, it

remains a highly adaptable plant and, consequently, a dynamic drug, requiring
constant reassessment

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Greengenes707 said:

Great info guys.

I like the talk about adaptation. I totally agree. I was originally an outdoor grower, and the theory of climatization is well based and true. Over a couple generations in reoccurring area, a strain optimizes it's self to the local conditions. Conditions from temps, elevation, humidity, wind, long & lat, light, all things really.

I don't run beans indoors so I have never got to test my varied theory of climatization, but I would like to see a strain developed and climatized under LED's. Some european breeders do use led's, but there goal is not creating an strain optimized for led performance...I guess each led brands spectrum would be a little off...but as far as what the plants are seeing I think it would be generally closer than a strain optimized under hps. I think of guys like scraehole who breeds his auto's under induction, and has some of the biggest autos I've seen.
I even wonder if on the first generation bean grown with led's from the start would be better than a strain that has been germinated, propagated, and grown under hps/mh/t5 for some time.

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lax123 said:

Ah, you meant adaption via (natural) selection. So like a breeder that uses leds and couples the best flourishing ones/ones with favorable traits. Now I get it.

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Abstract

Light-emitting diodes (LEDs) are an emerging technology for plant growth lighting. Due to their narrow spectral output, colored LEDs provide many options for studying the spectral effects of light on plants. Early on, efficient red LEDs were the primary focus of photobiological research; however, subsequent studies have shown that normal plant growth and development cannot be achieved under red light without blue light supplementation. More recent studies have shown that red and blue (RB) LEDs supplemented with green light increase plant dry mass. This is because green light transmits more effectively through the leaf canopy than red and blue light, thus illuminating lower plant leaves and increasing whole-plant photosynthesis. Red, green and blue (RGB) light can be provided by either a conventional white light source (such as fluorescent lights), a combination of RGB LEDs, or from recently developed white LEDs. White LEDs exceed the efficiency of fluorescent lights and have a comparable broad spectrum. As such, they have the potential to replace fluorescent lighting for growth-chamber-based crop production both on Earth and in space. Here we report the results of studies on the effects of three white LED types (warm, neutral and cool) on plant growth and development compared to combinations of RB and RGB LEDs. Plants were grown under two constant light intensities (200 and 500 μmol m-2 s-1). Temperature, environmental conditions and root-zone environment were uniformly maintained across treatments. Phytochrome photoequilbria and red/far-red ratios were similar among treatments and were comparable to conventional fluorescent lights. Blue light had a significant effect on both plant growth (dry mass gain) and development (dry mass partitioning). An increase in the absolute amount (μmol m-2 s-1) of blue light from 0-80 μmol m-2 s-1 resulted in a decrease in stem elongation, independent of the light intensity. However, an increase in the relative amount (%) of blue light caused a decrease in specific leaf area (leaf area per unit leaf mass). As the relative amount of blue light increased, chlorophyll concentration per unit leaf area increased, but chlorophyll concentration per unit leaf mass remained constant. The relative amount of blue light increased total dry mass in some species while it remained constant in others. An increase in the fraction of green light increased dry mass in radish. Overall, white LEDs provided a more uniform spectral distribution, reduced stem elongation and leaf area, and maintained or increased dry mass as compared to RB and RGB LEDs. Cool white LEDs are more electrically efficient than the other two white LEDs and have sufficient blue light for normal plant growth and development at both high and low light intensities. Compared to sunlight, cool white LEDs are perhaps deficient in red light and may therefore benefit from supplementation with red LEDs. Future studies will be conducted to test this hypothesis. These results have significant implication for LADA growth chambers which are currently used for vegetable production on the International Space Station. [HR][/HR]

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The accepted dogma in light biology is that

all wavebands of visible light promote
photomorphogenesis

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Many examples exist in biology in which
multiple systems oppose each other in order to
fine tune responses and conserve

valuable resources. In this sense,
green wavebands may lead to

conservation of valuable resources and extension
into regions of more optimal light.

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