Please explain the phrase "Penetration" in reference to lights.

[Tater]

Yeah I had fun and learnt something as well and really thats what these forums are all about. If all I ever saw were threads about using MJ soil or how much nutes to feed my plant when that information is all readily available I would most likely simply just leave the forum. As long as threads like this exist and there is intelligent debate I will gladly stick around and partake. Nice thread Mr. President of the United Smokers.

 

[KGB30]

Oh man this thread is over it was nice learning while it lasted..

 

[massproducer]

I just couldn't resist posting this... From the overgrow FAQ

Fan leaves account for the greatest area for the reception of photons on a plant, thus they account for the majority of photosynthesis which occurs within a plant. Cells in the plant's leaves, called chloroplasts, contain a green pigment called chlorophyll which interacts with sunlight to split the water in the plant into its basic components. Leaves only absorb about 15% of the solar energy that hits them, the other 85% passes through-- but they reflect all the green light, which means it looks darker below the leaf to a human than it does to the plant because our eyes are most sensitive to the green spectrum (Shipperke, 03.15.2002).


hxxp://www.growfaq.net/growfaq/1546.htm

 

[Dub_j]

lol, even after 40 years of experience this thread remains pointless, i think people will just be confused by all the ego driven opinions. there are so many ways to grow, the plants pretty much grow themselves once planted, it is called weed for a reason. regardless, now that we all know the meaning of penetration and how it is relevant to growing, lets not post fiction based opinions for everyone to be confused by.

 

[POTUS]

lol, even after 40 years of experience this thread remains pointless, i think people will just be confused by all the ego driven opinions. there are so many ways to grow, the plants pretty much grow themselves once planted, it is called weed for a reason. regardless, now that we all know the meaning of penetration and how it is relevant to growing, lets not post fiction based opinions for everyone to be confused by.

Sorry pal, you're the one posting fiction.

It's obvious by what you've just said that you have no idea what you're talking about. You should be silent. It's odd that you would try to pump your own ego by posting the unnecessary crap you just did, while trying to make others sound less than useful.

You're so wrong about how and why "weed" grows, that it's actually amusing to read your uninformed bull.

Please, keep posting. We all need examples of what isn't correct. You've helped supply that need.

What you CAN do is post what it is SPECIFICALLY that you think is fiction. The posters who presented it can have a chance to show their side of the argument instead of you just posting silly crap like what I just quoted.

 

[POTUS]

I just couldn't resist posting this... From the overgrow FAQ

Fan leaves account for the greatest area for the reception of photons on a plant, thus they account for the majority of photosynthesis which occurs within a plant. Cells in the plant's leaves, called chloroplasts, contain a green pigment called chlorophyll which interacts with sunlight to split the water in the plant into its basic components. Leaves only absorb about 15% of the solar energy that hits them, the other 85% passes through-- but they reflect all the green light, which means it looks darker below the leaf to a human than it does to the plant because our eyes are most sensitive to the green spectrum (Shipperke, 03.15.2002).


hxxp://www.growfaq.net/growfaq/1546.htm

If you include all of the light that can be produced by the sun that isn't useful to plants, then yes, I would agree. We could also discuss moonlight, starlight, car lights and flashlights hitting the plants, but it wouldn't make any more sense than talking about the spectrum of light that make up that supposed 85%. Of course, the light produced by artificial means is much narrower in spectrum than that of the sun.

Plants use radiant energy of wavelengths in the 400- to 850-nanometer (nm) range.

The spectrum of electromagnetic radiation striking the Earth's atmosphere is 100 to 10,000,000 nanometer (nm). This can be divided into five regions in increasing order of wavelengths:

Ultraviolet C or (UVC) range, which spans a range of 100 to 280 nm. The term ultraviolet refers to the fact that the radiation is at higher frequency than violet light (and, hence also invisible to the human eye). Owing to absorption by the atmosphere very little reaches the Earth's surface (Lithosphere). This spectrum of radiation has germicidal properties, and is used in germicidal lamps.

Ultraviolet B or (UVB) range spans 280 to 315 nm. It is also greatly absorbed by the atmosphere, and along with UVC is responsible for the photochemical reaction leading to the production of the Ozone layer.

Ultraviolet A or (UVA) spans 315 to 400 nm. It has been traditionally held as less damaging to the DNA, and hence used in tanning and PUVA therapy for psoriasis.

Visible range or light spans 400 to 700 nm. As the name suggests, it is this range that is visible to the naked eye.

Infrared range that spans 700 nm to 106 nm [1 millimeter (mm)]. It is largely responsible for the warmth or heat that the sunlight carries. It is also divided into three types on the basis of wavelength:

Infrared-A: 700 nm to 1400 nm
Infrared-B: 1400 nm to 3000 nm
Infrared-C: 3000 nm to 1 mm.

As shown above, with natural sunlight, it's WAY more than 85% of the available light that isn't used by plants. Many wavelengths pass directly through the leaf as though it wasn't there; "X-Rays" being the most obvious.

However, with the narrow restrictions of plant usable light, that light that can pass through a leaf from an *artificial* source of light is debatable. I'd like to read any data you have or can find that has been discovered through scientific method.

I love the grow faq, but please keep in mind that non-professionals wrote most of it. Proof of scientific claims should be able to be backed by studies done utilizing scientific method. If no proof can be found, then it doesn't mean that the data isn't correct; only that it can't be supported with proof.

Peace!

 

[Hick]

lol, even after 40 years of experience this thread remains pointless, i think people will just be confused by all the ego driven opinions. there are so many ways to grow, the plants pretty much grow themselves once planted, it is called weed for a reason. regardless, now that we all know the meaning of penetration and how it is relevant to growing, lets not post fiction based opinions for everyone to be confused by.

..." the plants pretty much grow themselves once planted,"... lol.. yoou should relate that to some of the folks posting in the "Sick Plants" section..
..huh.. and "I" thought it was a pretty informative discussion, carried out in a mature manner. Where contrary facts and opinions were expressed, dissected, discussed without personal insults being exchanged... at least by the "ones contributing" any relative information.
So called .. "weed" requires a few basic things in order to grow. Light being one of them.. But in order to "thrive" and grow to its potential, .."weed" requires quality light, in the proper spectrum, nutrients, in ratios and consistant supply, fresh air or co2 in abundance, ect. ect. . .. "Weed" will grow with less than ideal conditions.. but this discussion was/is addressing more advanced aspects of maximizing growth. Not just simply allowing it to "grow itself", and hoping for the best.
If you have something to "contribute".. post it. If you don't, don't post.. pretty simple.

 

[Dub_j]

In fact, almost all light does NOT pass through the leaf barrier of a plant. The little that does, does nothing for the plant in regards to producing usable weed.

let me know if you'd like another..
i have done nothing but water and fertilize my plants, and as of now they are 5 feet outdoors, maybe i'm lucky... im not trying to be a jerk, its just seems like this thread/( your invitation for someone to explain the prahse "penetration" in reference to lights) was more of a challenge for someone to provide more correct context than you did, rather than helping you understand the phrase.

 

[massproducer]

With chlorophyll being the main cell able to absorb light for plant use, but chlorophyll only being produced in narrow bands in the leaf, it would lead me to believe that the excess usable light must either pass through the leaf or become trapped within the leaf. I subscribe to the passing through.

The structure of a leaf itself lends to my belief as well, as it has a transparant waxy layer on top used to hold in moisture and allow maximum amounts of usable light into the second layer of the leaf where the light absorbing cells are in narrow bands. After that layer you are moving into the layer where the secondary pigment light absorbing cells are which absorb even less light the chlorophyll does. After that layer we are moving into the stoma, and underside of the leaves.

Look at your very shaded leaves or buds that are close to the light, like lower buds on the main cola, I bet they will be still growing great but i also bet that they will be a very light green colour because they are recieving most of the spectrums but because they get no direct light rays they there is no green light to filter as such no green colour.

 

[massproducer]

Instead of me always trying to prove my point, why doesn't someone show me why they would think that light can not pass through leaves? Because I failed to find anything stating the likes.

This has now evolved into the Question of

Can usable light penetrate leaves? Which I believe it can and at a very high rate

 

[massproducer]

Lets just try and keep things civil, i love a good debate but lets try and stay above the belt.

 

[POTUS]

Instead of me always trying to prove my point, why doesn't someone show me why they would think that light can not pass through leaves? Because I failed to find anything stating the likes.

This has now evolved into the Question of

Can usable light penetrate leaves? Which I believe it can and at a very high rate

I'll explain easily why the usable light *isn't* passing through the leaf.

Visible light and light that is usable to a plant are mostly in the same spectrum with the exception of some UV.

If you return to my statement about using a light meter beneath the plant canopy, you'll see that the lux that passes through the leaf is degraded to the point of almost not being there.

That's the same light that the plant needs to use.

The very first layer of leaf might actually let enough light through to help the second layer, but that's two layers of what? Twenty or so?

By the time the light has reached it's stopping point, it's not reached anywhere near the bottom of the canopy of plants that form a thick canopy at the top, (four footers or so).

With a good breeze blowing through the plant, it might displace enough leaves to let light through, but that's the only light I see doing any good.

 

[massproducer]

visable light and light the plant uses are not exactly the same spectrum... Visable light is mainly in the green and yellow spectrum, which are the spectrums that plants use the least and as such reflect. Yes we can see from 400 - 700, but we mainly see what the plant doesn't, which is right in the middle, the green and yellow, that is what our eyes are most conditioned to see. That is a reason that a halogen bulb does really nothing for plant growth, but sure seems bright to our eyes

That is 2 layers of 3-4, you have to do a bit more research on the structure of a leaf and the photosynthesis.

hxxp://en.wikipedia.org/wiki/Leaf


Quantum mechanical effects
Through photosynthesis, sunlight energy is transferred to molecular reaction centers for conversion into chemical energy with nearly 100-percent efficiency. The transfer of the solar energy takes place almost instantaneously, so little energy is wasted as heat. However, only 43% of the total solar incident radiation can be used (only light in the range 400-700 nm), 20% of light is blocked by canopy, and plant respiration requires about 33% of the stored energy, which brings down the actual efficiency of photosynthesis to about 6.6%

hxxp://en.wikipedia.org/wiki/Photosynthesis#Origin_of_chloroplasts


How can 20% of the light be blocked by the canopy if it can not penetrate the leaves. Funny how this sound similar to the numbers that I posted in an earlier post, where the overgrow synopsis on fan leaves stated that up to 85% of light pass through leaves with the plant's cells only absorbing 15%

So are you saying that you have tested your theory with a light meter? Because as I said, all of the research I have been doing are showing me that light can easily pass through leaves.

 

[massproducer]

To me it is somewhat simple...If light were blocked by leaves then firstly leaves would have to be opaque, which we know they are not, they are more like smoked glass, and light sure gets through smoked glass, secondly you couldn't grow buds that were being shaded because they would recive absolutly no light, but I also know that that is not true, shaded buds grow find, just a bit lighter green because they are no getting enough green light to reflect.

 

[massproducer]

A light-adapted eye generally has its maximum sensitivity at around 555 nm (540 THz), in the green region of the optical spectrum

http://en.wikipedia.org/wiki/Visible_spectrum

So we see light mainly in the green spectrum, but that happens to be the exact colour that plants can not use and so reflect it. This is the reason I can understand that people would think that light is just reflected if not absorbed, but in fact it is just because we have an easier time seeing the green that is being reflected while the wavelengths that are passing through we have a much harder time seeing. That will cause it to look rather dark under the canopy but that does not mean light is not passing through

 

[POTUS]

So are you saying that you have tested your theory with a light meter? Because as I said, all of the research I have been doing are showing me that light can easily pass through leaves.

Yes, I've seen the lux drop under a full canopy. The plants were just going into flower and almost no light was reaching below the canopy. A friend who was a professional photographer was taking pics of his grow. I wasn't close enough to see the digits on the meter, but the reading dropped like a rock. He had to use supplemental light to take his shots.

If you can borrow one from someone and do the test yourself, you'll understand what I'm saying.

I think perhaps we're disagreeing on what light passes through a leaf. I'll have to dig a little and see if I can come up with some reputable studies that mention the subject matter in enough detail to mean something to our discussion.

I mentioned scientific method in an earlier post. Again, I have to caution you that neither Wikopedia nor most of the quoted "scientific" facts in the Grow Faq are the results of scientific method. I'm sure there are lots of facts on this subject that *are* proven via scientific method, and I'll try to find some on the net.

If you have any test results that have proven your argument via repeatable testing using scientific method, then I would love to read it and would gladly admit having learned something different from what I currently hold true.

From: The Solar Greenhouse Book

Only 37% of the energy in sunlight is within the wavelength (colors) useful for photosynthesis, while 62.4% is infrared (thermal energy) and the remaining 0.6% is ultraviolet. Photosynthesis in the plant leaf is powered by 1% of the sunlight that falls on the plant, 10% of that 1% is reflected and 10% passes through the leaf. The leaf will retain 80% which is used for transpiration. Some of the light is re-radiated, while the fraction that remains is used for building food from the carbon dioxide, minerals and water.

****

The 10% that passes through the leaf will then follow the same ratios when it strikes the second leaf from the top, which on my grows is about 4 inches below the top layer. By the time the light has passed through two leaves, virtually no usable light remains. It's mostly green and at a very reduced intensity.

If you like, I can order that book and research it's bibliography. Through a simple trail of references, we can dig up a cart load of data on the subject.

Do you have a library near you that you can order books through the "Intra-Library Loan" service? Mine does for any book in print. All I need is the ISBN number and about three weeks.

If you do, you can order a few for review and I'll do the same. We'll have a ton of references that will show the test results from repeatable testing via scientific method.

We can put this on hold until the data is collected.

Paperback: 328 pages
Publisher: Rodale Pr (February 1978)
ISBN-10: 0878572228
ISBN-13: 978-0878572229

The Solar Greenhouse Book (Paperback)
by James C. McCullagh (Editor)

Interlibrary Loan / Purchase Request
Your request has been successfully submitted, you will be contacted when the request has been fulfilled.

***
I'll get this one and see what references he has.

 

[POTUS]

A light-adapted eye generally has its maximum sensitivity at around 555 nm (540 THz), in the green region of the optical spectrum

So we see light mainly in the green spectrum...

No, that's not what that means at all. It means exactly what it says; "Maximum sensitivity", not mainly seen. The human eye sees all the spectrum's from blue to red. Literally, if we didn't, we couldn't see a "rainbow" or any prism deflected colors clearly. Green would be the brightest and sharpest if that were true. We see almost all the colors at close to the same intensity. We are just "more sensitive" to green variations.

 

[Tater]

I have nothing to add other than encouragement. These are the types of threads that belong in grow faqs well once we sort the wheat from the chaff.

 

[POTUS]

let me know if you'd like another..
i have done nothing but water and fertilize my plants, and as of now they are 5 feet outdoors, maybe i'm lucky... im not trying to be a jerk, its just seems like this thread/( your invitation for someone to explain the prahse "penetration" in reference to lights) was more of a challenge for someone to provide more correct context than you did, rather than helping you understand the phrase.

"let me know if you'd like another.."

I have no idea what you mean by this. Please explain it in a complete sentence.

"the plants pretty much grow themselves once planted, it is called weed for a reason."

Another quote of your opinion. It seems that you don't follow your own judgement very well; "i have done nothing but water and fertilize my plants", well, that's NOT what happens to weeds. Please tell me the last time you went out and watered and fertilized the weeds in your yard. Exactly, NEVER. You've supplemented the actions of nature by providing more water than nature did and you also provided nutrients that weren't supplied by nature.

"im not trying to be a jerk, its just seems like this thread/( your invitation for someone to explain the prahse "penetration" in reference to lights) was more of a challenge for someone to provide more correct context than you did, rather than helping you understand the phrase."

It seems that the only thing you have done is to post comments that make you sound like a jerk, so denying it is pointless. Obviously, the discussion is beyond your comprehension. I would suggest that you be quiet and try to learn something.

Frankly man, your story gets worse every time you post. Instead of being a smart mouth to gain attention, I would suggest that you stop posting until you know what it is you're saying.

Maybe you'd be happy at one of those other groups where people look up to wise azzes.

This one doesn't.

If your comment "let me know if you'd like another.." means to let you know when I want you to post more nonsense, then I'll tell you the obvious now; I'd like you to be quiet until you have something worthwhile to say. However, people who act like you are seldom keep quiet. It seems against their nature and doesn't get them the attention they require, so I have no doubt we'll hear more negative baloney from you.

 

[Tater]

Whoa whats that all about? If you don't want to be part of the discussion and are happy with the way you are doing things then fine don't be part of the discussion. Other people (including myself) have enjoyed this thread and have been able to take something from it. Whats wrong with debate and discussion? Its you that is out of line, and the back button is located at the top of your browser feel free to use it if you don't like what you are reading.