P
Phyzix
Guest
Thanks for the tip, hardly a concern for me fortunatelyHappens all the time if ya want to see it just google "light bleaching leaves" first thing that comes up is RIU
Careful, you CAN give plants too much light
- Thread starter Toppers
- Start date
Why would i make that up, just sharing my experiences. Heres the pictures of my current grow, hood on left is 600w, right is 400w hps, both are cooled by one 4 inch inline fan.
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monkz
Well-Known Member
i duno why he'd imply that just because you only have 12 posts that you were lying.. ffs people on this site have thousands of posts and they still dont know what the hell theyre on about.
some dicks on riu man
guitarguy10
Well-Known Member
I don't mean to troll this thread, but I wish to put forth a compelling explanation as to why there is no such thing as too much light (lumens, not talking heat generation, etc.) during veg. growth
I realize i'm digging up an old thread, but am doing so to give some ... technical, and succinct biochemical discussion about.
That being said, what is to proceed contains many big, and stupidly named biochemicals, so ... I R SRY
Plants need light because they need to make 'food'. What is 'food', basically any 3, 5, or 6 chain carbon compounds produced during the calvin cycle, the most important being glyceraldehyde-3-phosphate (G3P, a 3 carbon molecule) as it's an instant energy source to the plant (it will be used to regenerate ribulose-1,5-bisphosphate, or RuBP which is the starting biochemical in the Calvin cycle, and thus its concentration regulates how or if the next iteration of the Calvin cycle will proceed). MORE IMPORTANTLY though, plants combine 2 G3P's to produce 6 carbon cyclic molecules. For those not in the know, the definition of carbohydrate is a cyclic carbon molecule
... in other words this is how the plant makes food, this produce of the 2 G3Ps is Glucose ... sugar, which the plant then stores all throughout itself to live off of.
The important thing about everything I just said is that these things don't just combine to form new compounds without some driving force. These driving forces are two molecules called ATP and NADPH (whose 'depleted' forms are ADP and NADP+).
Plants generate them through photosynthesis. Chlorophyll absorbs light, generates electrons which flow through electron transport chain, and in turn generate an active transport of H+ across the membrane containing depleted NADP+ (of course the entire process of photosynthesis with photosystem I and II, various chlorophyll isoforms ... uh, you get why i'm gonna stop there and just describe what I need to
).
When I say 'active transport' I mean more accurately an induced electrochemical gradient (via the shutting of H+ across its gradient) which generates an activated ATP 'energy molecule' through this process scientists have fancily named chemiosmosis. The NADP+ is also reduced by the electron, and the H+ thats now sitting there to produce the activated NADPH 'energy molecule'.
So we know light = energy molecules (ATP, NADPH). We know that the Calvin cycle, which is what the plant uses to produce their food require these energy molecules, so photosynthesis and the Calvin cycle are intrinsically linked. I bring up this point because the Calvin cycle is often referred to as the 'Dark Cycle', which would lead most to believe it is a metabolic process that only occurs in the dark.
This is wrong, the reason it's called the 'dark cycle' is because SOME of the reactions in the Calvin cycle can occur without light (whereas every other metabolic process in a plant requires light, eg. photosynthesis systems)
Now, the reason that plants can never have too much light (drum roll). The only way a plant can grow is to anabolize itself food through the Calvin cycle. I said before that RuBP was the limiting factor in the Calvin cycle so lets call that 'step one'. This is converted 'ultimately' into two 3 carbon molecules called 3-phosphoglycerate via (step 2). One of these goes off to function in other metabolic processes (eg. making up the enzymes and precursors needed for each step of a metabolic process). These two steps are light independent meaning they can occur in the dark. The other 3PG though goes on to continue the Calvin cycle. Without it, the Calvin cycle would cease and the plant would stop making food (the quantities of each molecule are fundamental to a metabolic process, its cyclic so any break will halt the whole thing). This 3PG is converted into 1,3-bisphosphoglycerate next in the cycle (step ... 3). The pivotal point now is that enzyme necessary to do this, obviously called phosphoglycerate kinase is LIGHT DEPENDENT. The Calvin cycle cannot proceed without it, and thus neither can growth.
The point i'm trying to get across here is that it has been confused with the use of the term 'dark cycle' that there are plant functions relating to growth (i'm talking about vegetative state here, the duration of light obviously affects auxins and cytokins, relating specifically to induced flowering) that can ONLY occur in the dark, and thus it is necessary to have a dark period for these reactions to occur, when in fact these 'dark reactions' just mean they can occur either in the presence OR absence of light (opposed to every other plant metabolic function which requires light).
A plant can be grown with no darkness whatsoever, and carry out every single one of its metabolic functions in a normal capacity. There are 3 different categories of plants (C3, C4, and CAM) that define how they conduct the RuBP --> 3PG reaction, and this is really the only differential factor in how a plant conducts its metabolic business. If you're still with me you'll note that this is a light independent step, so in other words claims the C3, C4, CAM designations on whether a plant requires less/more light are COMPLETELY FALSE. I am pointing this out because i've read several threads saying that because cannabis is a C3 plant it requires no 'dark period', which is absolutely incorrect, as I just described in exquisite detail above)
On the topic of the leeching thing, this too is also a misnomer because we are talking about moving a plant from one environment to another. Chlorophyll is a pretty cool molecule actually because it's very similar to human blood in that it has a heme group, but instead of an iron atom in the middle (like in human blood) there's a magnesium atom (which is probably why Mg deficiency is one of the more common plant anemia's, plant is growing so fast, rather producing chlorophyll so fast that eventually it can't because there is no Mg, and then metabolic precursors are backed up, and presumably are what cause the qualitative symptoms, but *shrug* could be wrong, just a hypothesis).
Anyways back to topic, if say you're growing indoors, the rate of chlorophyll production will be high (which is good, because you want big healthy sexy plants), as too would be the light dependent (ATP/NADPH) production phosphoglycerate kinase to push one of the 3PG to 1,3-bisphosphoglycerate (thus committing it into the Calvin cycle). The reason being that whatever timing you use, 18/6, 20/4, or 24/0 the plants are receiving that exact same amount of light each day, and thus have established equilibrium in the metabolic flux of light dependent biochemicals (and equilibrium basically just means highest efficiency).
When you move your plants to somewhere where the daylight fluctuates the problem arises in the loss of this equilibrium. What I mean is, for a plant to manufacture chlorophyll it must do so with the precursor protochlorophyllide (this is basically the heme group I talked about earlier, this is just the fancy science term for plant blood). This compound requires ATP to make the chlorophyll molecule, and ATP is largely generated via light dependent reactions (eg. chlorophyll). When you alter the metabolic flux of ATP production (by changing light duration) among many other things you are altering the rate of which 3PG --> 1,3-bisphosphglycerate. Like I said before this compound is what continues the Calvin cycle (vs. the 3PG being used for other metabolic processes). The Calvin cycle is what produces the plant's food, so altering the metabolic flux of one of its steps will inhibit it from doing its function of producing food(sugar, carbs). Sugar, carb's just so happen to be what makes up protochlorophyllide. If Calvin cycle is being slowed, so too will sugar production, and thus so to protochlorophyllide production and thus to chlorophyll production. Its sort of a vicious circle where the fluctuation in light duration limit chlorophyll's ability to generate energy, which slows sugar production which slows chlorophyll production .. repeat.
I personally have never seen this 'leeching' and no one has ever even produced a credible picture to me. The effects I just described would affect the plant's rate of growth, any lightening of colour is either mildew, or the plant trying to re-equilibriate to its new environment, which means producing the 5 isoforms of chlorophyll in different proportions, whatever is required to re-establish metabolic equilibrium (and each isoform absorbs light at a different wavelength and are thus ... different colours). It could also be a change from a very high N soil to outdoor soil, or hell any myriad of other things.
If you're still reading this ... congratulations !
If you're angry I just wasted all your (precious) time, well then why the hell did you keep reading dummy ? !
Very bored day, very stoned, and very much in the mood to clear up .. at least one of the growing misconceptions this thread represents. Nevertheless, I hope SOMEONE found this to be at least ... intellectually stimulating
PS: I didn't just glue together some snippets from various wiki sites, that was all from the top of my head (I am a real and bonified egghead scientist), so if there are any mistakes, please do correct me
PPS: There is one valid contribution for a few hours of darkness a day, and that relates back to auxins and cytokinins i mentioned earlier. Basically darkness kinda redirects the plant's energy into root development, so is very important
I realize i'm digging up an old thread, but am doing so to give some ... technical, and succinct biochemical discussion about.
That being said, what is to proceed contains many big, and stupidly named biochemicals, so ... I R SRY
Plants need light because they need to make 'food'. What is 'food', basically any 3, 5, or 6 chain carbon compounds produced during the calvin cycle, the most important being glyceraldehyde-3-phosphate (G3P, a 3 carbon molecule) as it's an instant energy source to the plant (it will be used to regenerate ribulose-1,5-bisphosphate, or RuBP which is the starting biochemical in the Calvin cycle, and thus its concentration regulates how or if the next iteration of the Calvin cycle will proceed). MORE IMPORTANTLY though, plants combine 2 G3P's to produce 6 carbon cyclic molecules. For those not in the know, the definition of carbohydrate is a cyclic carbon molecule
... in other words this is how the plant makes food, this produce of the 2 G3Ps is Glucose ... sugar, which the plant then stores all throughout itself to live off of.The important thing about everything I just said is that these things don't just combine to form new compounds without some driving force. These driving forces are two molecules called ATP and NADPH (whose 'depleted' forms are ADP and NADP+).
Plants generate them through photosynthesis. Chlorophyll absorbs light, generates electrons which flow through electron transport chain, and in turn generate an active transport of H+ across the membrane containing depleted NADP+ (of course the entire process of photosynthesis with photosystem I and II, various chlorophyll isoforms ... uh, you get why i'm gonna stop there and just describe what I need to
). When I say 'active transport' I mean more accurately an induced electrochemical gradient (via the shutting of H+ across its gradient) which generates an activated ATP 'energy molecule' through this process scientists have fancily named chemiosmosis. The NADP+ is also reduced by the electron, and the H+ thats now sitting there to produce the activated NADPH 'energy molecule'.
So we know light = energy molecules (ATP, NADPH). We know that the Calvin cycle, which is what the plant uses to produce their food require these energy molecules, so photosynthesis and the Calvin cycle are intrinsically linked. I bring up this point because the Calvin cycle is often referred to as the 'Dark Cycle', which would lead most to believe it is a metabolic process that only occurs in the dark.
This is wrong, the reason it's called the 'dark cycle' is because SOME of the reactions in the Calvin cycle can occur without light (whereas every other metabolic process in a plant requires light, eg. photosynthesis systems)
Now, the reason that plants can never have too much light (drum roll). The only way a plant can grow is to anabolize itself food through the Calvin cycle. I said before that RuBP was the limiting factor in the Calvin cycle so lets call that 'step one'. This is converted 'ultimately' into two 3 carbon molecules called 3-phosphoglycerate via (step 2). One of these goes off to function in other metabolic processes (eg. making up the enzymes and precursors needed for each step of a metabolic process). These two steps are light independent meaning they can occur in the dark. The other 3PG though goes on to continue the Calvin cycle. Without it, the Calvin cycle would cease and the plant would stop making food (the quantities of each molecule are fundamental to a metabolic process, its cyclic so any break will halt the whole thing). This 3PG is converted into 1,3-bisphosphoglycerate next in the cycle (step ... 3). The pivotal point now is that enzyme necessary to do this, obviously called phosphoglycerate kinase is LIGHT DEPENDENT. The Calvin cycle cannot proceed without it, and thus neither can growth.
The point i'm trying to get across here is that it has been confused with the use of the term 'dark cycle' that there are plant functions relating to growth (i'm talking about vegetative state here, the duration of light obviously affects auxins and cytokins, relating specifically to induced flowering) that can ONLY occur in the dark, and thus it is necessary to have a dark period for these reactions to occur, when in fact these 'dark reactions' just mean they can occur either in the presence OR absence of light (opposed to every other plant metabolic function which requires light).
A plant can be grown with no darkness whatsoever, and carry out every single one of its metabolic functions in a normal capacity. There are 3 different categories of plants (C3, C4, and CAM) that define how they conduct the RuBP --> 3PG reaction, and this is really the only differential factor in how a plant conducts its metabolic business. If you're still with me you'll note that this is a light independent step, so in other words claims the C3, C4, CAM designations on whether a plant requires less/more light are COMPLETELY FALSE. I am pointing this out because i've read several threads saying that because cannabis is a C3 plant it requires no 'dark period', which is absolutely incorrect, as I just described in exquisite detail above
)On the topic of the leeching thing, this too is also a misnomer because we are talking about moving a plant from one environment to another. Chlorophyll is a pretty cool molecule actually because it's very similar to human blood in that it has a heme group, but instead of an iron atom in the middle (like in human blood) there's a magnesium atom (which is probably why Mg deficiency is one of the more common plant anemia's, plant is growing so fast, rather producing chlorophyll so fast that eventually it can't because there is no Mg, and then metabolic precursors are backed up, and presumably are what cause the qualitative symptoms, but *shrug* could be wrong, just a hypothesis
). Anyways back to topic, if say you're growing indoors, the rate of chlorophyll production will be high (which is good, because you want big healthy sexy plants), as too would be the light dependent (ATP/NADPH) production phosphoglycerate kinase to push one of the 3PG to 1,3-bisphosphoglycerate (thus committing it into the Calvin cycle). The reason being that whatever timing you use, 18/6, 20/4, or 24/0 the plants are receiving that exact same amount of light each day, and thus have established equilibrium in the metabolic flux of light dependent biochemicals (and equilibrium basically just means highest efficiency).
When you move your plants to somewhere where the daylight fluctuates the problem arises in the loss of this equilibrium. What I mean is, for a plant to manufacture chlorophyll it must do so with the precursor protochlorophyllide (this is basically the heme group I talked about earlier, this is just the fancy science term for plant blood). This compound requires ATP to make the chlorophyll molecule, and ATP is largely generated via light dependent reactions (eg. chlorophyll). When you alter the metabolic flux of ATP production (by changing light duration) among many other things you are altering the rate of which 3PG --> 1,3-bisphosphglycerate. Like I said before this compound is what continues the Calvin cycle (vs. the 3PG being used for other metabolic processes). The Calvin cycle is what produces the plant's food, so altering the metabolic flux of one of its steps will inhibit it from doing its function of producing food(sugar, carbs). Sugar, carb's just so happen to be what makes up protochlorophyllide. If Calvin cycle is being slowed, so too will sugar production, and thus so to protochlorophyllide production and thus to chlorophyll production. Its sort of a vicious circle where the fluctuation in light duration limit chlorophyll's ability to generate energy, which slows sugar production which slows chlorophyll production .. repeat.
I personally have never seen this 'leeching' and no one has ever even produced a credible picture to me. The effects I just described would affect the plant's rate of growth, any lightening of colour is either mildew, or the plant trying to re-equilibriate to its new environment, which means producing the 5 isoforms of chlorophyll in different proportions, whatever is required to re-establish metabolic equilibrium (and each isoform absorbs light at a different wavelength and are thus ... different colours). It could also be a change from a very high N soil to outdoor soil, or hell any myriad of other things.
If you're still reading this ... congratulations !
If you're angry I just wasted all your (precious) time, well then why the hell did you keep reading dummy ? !
Very bored day, very stoned, and very much in the mood to clear up .. at least one of the growing misconceptions this thread represents. Nevertheless, I hope SOMEONE found this to be at least ... intellectually stimulating
PS: I didn't just glue together some snippets from various wiki sites, that was all from the top of my head (I am a real and bonified egghead scientist), so if there are any mistakes, please do correct me
PPS: There is one valid contribution for a few hours of darkness a day, and that relates back to auxins and cytokinins i mentioned earlier. Basically darkness kinda redirects the plant's energy into root development, so is very important
MajorCoco
Well-Known Member
I'm sure this thread is dead, so I may start a new one, but just wanted to like to the following:I don't mean to troll this thread, but I wish to put forth a compelling explanation as to why there is no such thing as too much light (lumens, not talking heat generation, etc.) during veg. growth
I realize i'm digging up an old thread, but am doing so to give some ... technical, and succinct biochemical discussion about.
That being said, what is to proceed contains many big, and stupidly named biochemicals, so ... I R SRY
Plants need light because they need to make 'food'. What is 'food', basically any 3, 5, or 6 chain carbon compounds produced during the calvin cycle, the most important being glyceraldehyde-3-phosphate (G3P, a 3 carbon molecule) as it's an instant energy source to the plant (it will be used to regenerate ribulose-1,5-bisphosphate, or RuBP which is the starting biochemical in the Calvin cycle, and thus its concentration regulates how or if the next iteration of the Calvin cycle will proceed). MORE IMPORTANTLY though, plants combine 2 G3P's to produce 6 carbon cyclic molecules. For those not in the know, the definition of carbohydrate is a cyclic carbon molecule
t
http://www.mendeley.com/research/photoinhibition-photosynthesis-causes-reduction-vegetative-growth-rates-dwarf-bean-phaseolus-vulgaris-plants/
...which states unequivocally that excessive light intensities caused a 25% reduction in relative growth rate of the test plants. What it does also add however is that the plant will acclimatize to the higher light levels, and the negative impact on growth (and presumably leaf bleaching, in not caused by heat) will reduce over time.
obrienross1123
Member
ya cause 8 inches is ridiculously close for a 1000w
sorethumb
Active Member
97 watts thats incredible if really true . and loved the sun is 10k at noon at the equator nowhere else. makes sence
420sm0keweed
Member
Hey guys my baby seems to not be doing so well, is a 1000w hps to much for a single plant? its 20" above it.. approx 10 days old from sproutView attachment 2591993View attachment 2591994View attachment 2591995View attachment 2591996
Trousers
Well-Known Member
There is no way you bleached a plant with a 250. I have a 250 and the buds can touch the reflector glass with no problem.
In my tent with my 600 watt hps, the leaves in the middle can get bleached while the leaves on the sides are perfect green.
I just bought a diffuser to see if that helps.
For me moving the light further makes for more stretching. Too close and the leaves bleach.
your buds would love it
In my tent with my 600 watt hps, the leaves in the middle can get bleached while the leaves on the sides are perfect green.
I just bought a diffuser to see if that helps.
For me moving the light further makes for more stretching. Too close and the leaves bleach.
lol, that makes no sense
your buds would love it
This is an old thread, but I'll chime in due to a recent mistake I made.
I have quite a bit of experience (12-15 successful grows), and I've always vegged under 400w MH, then switched over to 1000w HPS for flowering.
This grow I decided to try 1000w HPS throughout. Grown from seed, passive hydro. When the seedlings rooted, I put them under the 1000w light, approximately 42" away with temps in the low 80's, circulating fan, 400 ppm nutes. With the 400w MH, I always had good luck with exactly that process, except the seedlings were about 24" from the light and temps in the low 80s. So with the 1000w light, I tried upping the distance to compensate for the increased light. The little seedlings nearly fried -- not from the 83F temps -- from the intensity of the light. So I've back the light off to about 54". We'll see.
Interestingly, there does seem to be a genetic component to the light sensitivity among seedlings. Two of my twelve seedlings (mono-culture White Lightning) look almost normal and seem fine. Two are almost dead, though I haven't given up hope. The other 8 are in between -- clearly stressed but with hope of a full recovery.
My $.02 based on my experience.
I have quite a bit of experience (12-15 successful grows), and I've always vegged under 400w MH, then switched over to 1000w HPS for flowering.
This grow I decided to try 1000w HPS throughout. Grown from seed, passive hydro. When the seedlings rooted, I put them under the 1000w light, approximately 42" away with temps in the low 80's, circulating fan, 400 ppm nutes. With the 400w MH, I always had good luck with exactly that process, except the seedlings were about 24" from the light and temps in the low 80s. So with the 1000w light, I tried upping the distance to compensate for the increased light. The little seedlings nearly fried -- not from the 83F temps -- from the intensity of the light. So I've back the light off to about 54". We'll see.
Interestingly, there does seem to be a genetic component to the light sensitivity among seedlings. Two of my twelve seedlings (mono-culture White Lightning) look almost normal and seem fine. Two are almost dead, though I haven't given up hope. The other 8 are in between -- clearly stressed but with hope of a full recovery.
My $.02 based on my experience.
MSTRGRWR68
New Member
Light intensity absolutely CAN! be breached in any stage of any grow. has for to light during the vegetative stage some growers will leave lights on for 24 hours. Hence......not possible to give to MUCH light. I have read this thread and I know that you growers are discussing light intensity. with that being said the correct answer is YES! you can give your plants too intense of light during a grow. your research and don't get crazy with lumens it won't make your plant grow any stronger or faster. if your fan leaves are flat like they've been ironed you've probably got it rightOK I am going to clear up this internet misinformation. You ABSOLUTELY can have too much light. This occured in my plants with a 1000w hps at 8 inches from the plants. I grow with a water cooled fixture so heat is not a factor... Again, too much light is indeed possible. I moved the 1000w to 12 inches and the problem went away.
CFL grower111111
Member
I have a question does anyone know why my plant is turning light green in the middle I’m growing under 600 watt full spectrum grow light I’m running it’s botth switches on it puts off pinkish purple color growing in a 24by24by48 grow tent temp is 75. Humidity is 50
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Olive Drab Green
Well-Known Member
Because you’re flowering. When you initiate flowering via 12/12 light cycle, the hormones change and the growth tips prepare for flowering.
Olive Drab Green
Well-Known Member
Light intensity of 1500 PPFD or more can and will cause a reduction in growth and potential breakdown in metabolic processes. You can run 24/0 for months, but don’t do it above 1200 PPFD. Much less in seedling and early veg. I don’t think anyone was discussing time signatures?
Og grumble
Well-Known Member
1500w l.e.d too much for a 4x2x5 tent?
PlainfieldPuff
Well-Known Member
Lol if plants could withstand any amount of light we could ramp up photosynthesis so that the plant grows 1 ft per day.
rootforme
Well-Known Member
Scientific studies at various universities on cannabis have shown the greatest yield and potency occurs at about 1500µmol (the sweet spot) but cannabis also continues to increase yield and quality all the way up to 2000µmol and higher but after 1500µmol you experience diminishing returns.