superman403

I just got about 15 clones and there to small to put outside. I have them under a 24 hour light and i was wondering if that was the fastest way the would grow, if not please help me

panamajuice

I assume these are rooted clones... then yes, 24 hours of light will make them grow the fastest.

I usually put them under 24 hours of flourecent light while they root under a humidity dome for 2 weeks, then I put them on a 18 hours light photoperiod under a 1K HPS.

I could let them grow under 24 hours light, all the way to flowering BUT since I notice little diference between 24 and 18 I like saving on energy bills.

Hope this helps, let us know how it goes.

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The Fool

I would put newly cut clones on 18/6 since the dark period helps it grow the root system more than in the daytime.

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Xgone.

hey the fool

that is opinion, not fact.

The Fool

I believe it is fact, as the auxins in the terminal bud (the hormones that control growth) move down to the roots during dark time.

That is why you should put to-be topped plants under 18/6 (or any length of dark time).

That is why alot of people put clones under 18/6.

That is the only reason why 18/6 is an accepted setting here at this great community (besides with HID lights, for them to save electricity and cool off).

Correct me if I'm wrong.



superman- excuse me for sorrta highjacking your thread, although I doubt you're around...Although you're on right now....

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419 and Holding

I believe you are incorrect, sir.

As you seem to already know, plants have 2 cycles of events that occur throughout a "normal" day outside. They are 1) the Light cycle, and 2) the Dark cycle. Also these cycles are called Photosynthesis and Respiration.

However, what you might not know is that -while the name "Light cycle" is accurate - the name "Dark cycle" is not. The dark cycle (respiration) happens constantly, 24 hours a day. The only reason we dubbed it the "Dark" cycle is because it is the obvious opposite of the "Light" cycle. This explains how we CAN keep plants under 24/0, with not side effects. They are missing out on nothing.

So while plants need light for the light cycle (photosynthesis), they DO NOT need dark for the dark cycle (respiration).

Even if the root growth was controlled by respiration (which I'm not sure it is, but since I'm not sure, I'll let it be), turning off the lights wouldnt speed it up...because it's always happening.


I've personally never heard of putting to-be topped plants under 18/6....but that doesnt mean much (I'm sure I havent heard of alot of things lol)

But I do know that a majority of people you will talk to will tell you they put clones under 24/7, because clones need energy to root, and the energy they seek is of course, Light.

If this was the case (darkness speeding up root growth), why wouldn't people just put clones in constant darkness? Or at least 13/11 or 14/10. It would seem that more darkness would mean more (faster) root growth.

I just dont see the science or logic behind this....

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The Fool

Ah! Another bit of information that I didn't know.

As you can tell I'm still puddying holes.

I can't tell you exactly where I saw that bit of info on to-be topped plants, as I browse through here and get lost sometimes in info and links. But I can tell you I DID see it, I'll try to find it.

But if I'm correct in saying that auxins DO move to the roots, (Are you saying that the auxins don't leave the terminal bud?) then having the lights on 18/6 would allow the auxins to move to the roots before you cut the terminal bud, saving that built-up hormone so the plant wouldn't have to produce more. (translating to less stress on the plant and faster pickup)

Has anyone tried putting clones under 13 or 14 hours of light? If the auxins do indeed move, then it might be better for them.

I agree that clones do need light to root. But maybe that's why people use 18/6 as opposed to 13 or 14. So the clones get a sufficient amount of light and a good amount of dark.

It's as though I'm hanging by a thread into complete persuasion. The one thread that is holding me up is the (once adamante) thought that auxins are the hormones responsible for new growth, and they move through the plant during different times of the day. If you're saying they don't move from the terminal bud ever, then that will release the snag.

I hope you can clear this up. I mean, this was a foundational fact which I have built upon. So it is very important for me to know the truth about this.

Maybe grass hopper can help us! He's the botanical genius, right?

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"The idea is to remain in a state of constant departure, while always arriving. It saves on introductions and goodbyes." -Bill Wise, Boat-Car Guy

PAST GROWS:
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CURRENT GROW STATUS: Grape Punch [Bogglegum x Lifestar] Mother Grow: Pending

panamajuice

I did a side by side test where I put 4 clones in 24 hours light and 4 other clones from the same mother on 18/6, and after 8 days 3 out of my 4 (24hrs) clones were showing roots down the bottom. After 9 days all of the 24hrs clones had roots showing and only 1 of my 18/6 clones showed roots. After 11 days all clones had rooted.

It may be small diference but after that experiment I came to the conclusion that no night cycle was needed for rooting clones and that 24hrs light was the best to use for rooting clones.

Anyways when my clones are ready for vegetative growth, I do use 18/6 cause it saves on electricity. Not because the "DARK" cycle helps them grow bigger roots.

As stated above:

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419 and Holding

Ok....luckily I took biology last semester, so this is all fresh in my head....(as I scurry to my notebook )

It turns out that you are 1/2 right. (I suppose that makes me 1/2 right as well. )

Auxins are a growth hormone produced in the meristems of plants.
Meristems are areas of plants where plant growth occurs. They are the site of repeated cell division of unspecialized cells. After division, these unspecialized cells differentiate and become specialized in relation to the function(s) they will perform. There are two types of meristems: lateral and apical.

Apical meristems are the site of primary growth in a plant, and are located at the root and shoot tips. Here you can find unspecialised cells, which follow this sequence to become a functional part of the plant:

-New unspecialised cells become available at the meristems (the site of mitosis)
-These cells become elongated and undergo vacuolation
-They become specialised (differentiated) to perform a particular function
-They then form part of a permanent tissue which performs a particular role within the plant
-The cycle continues for growth and regeneration purposes

Lateral meristems can be found growing laterally (where else?) to the plant. Lateral meristems are responsible for the thickening of the shoots and roots (structural support). This is why trees have rings....as they get older, they grow thicker. Every year a new "ring" forms around the core.

Needless to say, what we are interested in is the apical meristems, since this is where NEW root growth occurs. Now with that being said, lets get back to auxins....

Auxins are responsible in promoting cell elongation, a process that is required before differentiation of a cell. It is able to this by promoting the intake of water, increasing the elasticity of the cell to cope with the increase of water taken in by the cell. One of the most common auxins (and the one we are concerned with) is indole acetic acid (IAA).

Indole Acetic Acid affects the root and shoot tips of the plant as follows:

Shoot Tip - No matter what the concentration (of IAA), IAA promotes growth in the shoot areas of a plant. (Although higher concentrations promote growth more.)

Root Tip - High concentrations of IAA in the root tip inhibit growth, while small amounts are enough to promote growth.

Obviously we are interested in how IAA reacts in the root tip. Thus, clearly we do not want high concentrations of IAA in the roots. This would not promote faster growth.

Now, lets look at light's role in this debate. Believe it or not, light actually destorys the IAA auxins. But this only happens in substaintial amounts when there is alot of IAA to begin with. For instance, a clone (a shoot tip that has been cut), has alot of IAA at it's tip. And since the clone is so small, the amount of IAA in relation to it's entire mass is very high (if you have a 3" clone, and the top inch is the growing tip, it is filled with IAA, whereas in a full grown plant, there is much more 'mature' plant matter than growing tips). So in the case of the clone, light will destroy some of the auxins. And since the IAA auxins do not want to be destroyed, they will begin to "travel" downward. The light is what makes the IAA auxins travel to the bottom of a clone. Thus, no darkness is neede to make this happen.

And actually, it is what we want to happen. When we plant a clone, we want all of its energy to be directed into producing roots. By having the light on 24/7, we are destroying the auxins in the growing tip (while forcing them to move downwards), thus inhibiting plant growth, which allows all (or most) of the plants energy to be diverted to growing roots. And it is no coinsidense that this is where the IAA auxins happen to be headed. Since a newly cut clone has no roots to contain the IAA auxins already, the growing tip donates them in response to the constant bathing of light we give them.

So whether they know it or not, this is the real reason why many people put their clones under 24/7 lighting. If you were to give the clone a dark period, that would enable the auxins to begin to make the plant grow, thus using up valuable energy (and therefore time). However, since the roots are under soil or in a pot, having the light on 24/7 does not restrict root growth.

To sum things up, auxins are not only located or produced in the 'terminal bud', as you put it (which i'm not 100% what that is I assume you mean the shoot tips though). Auxins are located everywhere in a plant. But the ones that promote growth, the IAA auxins, are found (and produced) in the root tips AND shoot tips. So no 'travelling' of auxins is needed to promote faster root growth. After the donation of initial IAA auxins from the tip, the roots begin to manufacture their own IAA, thus allowing the shoot tip to keep its share of IAA, and begin to grow.

Whew, what a mouthful. I hope this helps more than hurts . Feel free to ask anymore questions...hopefully I (or someone) will be able to answer.

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penguin

Interesting discussion, and good posts 419 , but are you sure that we are interested only in IAA?

Going back a few posts, there is considerable confusion about the "dark cycle" reactions. The Calvin Cycle takes place in the stroma of the chloroplast, and is perhaps better referred to as the "light-independent process".

The light-dependent reactions, which occur in the thylakoid membrane of the chloroplast, convert light energy to chemical bond energy of ATP & NADPH.

The light-independent process uses these products of the light reactions to reduce CO2 to C6H12O6 (glucose).

The light-dependent reactions occur only in the presence of light. When light is removed, the reactions stop. The light-independent reactions also occur in the presence of light, but will continue to occur in the absence of light as long as there is enough ATP and NADPH left over after the light-dependent reactions shut down.

The "dark cycle" reactions do occur during daylight, and cannot proceed without the ATP & NADPH produced by the light reactions. Photosynthesis is not complete without the products of the dark cycle.

Both the light reactions and the dark cycle (anabolic processes) are part of photosynthesis, occur in the chloroplast, and thus occur only in photosynthesizing tissues. This produces the energy (stored as bond energy of carbohydrates) that fuels plant metabolism and growth.


Photorespiration is another metabolic (catabolic) pathway that also occurs in the chloroplast. It consumes O2, evolves CO2, produces no ATP or glucose, and reduces photosynthetic output. Photorespiration occurs when CO2 is not available -- due either to a low CO2 concentration because of insufficient ventilation, or to the stoma being closed (hot, dry, bright days). This is why high temperature and low RH inhibits the growth rate of C3 plants, and why CO2 enrichment allows for higher temperature and lower humidity.


None of that is the same as cellular respiration that occurs in the mitochondria of cells of all tissue types, including non-phtosynthesizing tissues (e.g., roots). This is a catabolic process that breaks down glucose to produce O2, H2O, and energy (as ATP). Cellular respiration occurs regardless of whether it's light or dark, driven by carboyhdrates produces in the photosynthesizing tissues.

So hopefully that clarifies why the "dark cycle" is not really relevant to root growth.


Generally speaking, a longer period of photosynthesis will result in more energy available for plant growth and thus increase the rate of growth. This has been demonstrated with supplemental lighting in commercial greenhouses. However, the benefit of this increased growth rate must be weighed against the increased cost of electricity. There is a difference between maximum growth and optimized growth. Cost/ benefit analysis of supplemental lighting strategies for year-round greenhouse operators at high latitudes suggest that optimum results are obtained for day-nuetral crops using progressive supplemental lighting to maintain a 17/7 photoperiod. This optimum photoperiod is somewhat crop- and latitude-specific.

In the context of an indoor garden that is performing at near-peak effciency, I am of the opinion that the photoperiod used for mother plants, clones, and vegetative growth of rooted clones is not a major factor affecting yield efficiency (g/w/m). Certainly there are many other factors that have a much more significant impact on efficiency, such as: light intensity & quality, canopy depth & density, temperature + relative humidity + CO2 concentration, oxygen availability in the root zone, water status, nutrient profile, etc.

It is important to understand that maximizing efficiency (highest g/w/m and lowest cost $/g) involves drastically reducing or eliminating the vegetative growth period entirely (i.e., growing from cuttings rather than seed).

In my setup, most of the veg side wattage has been devoted to mothers, upon which clone demand is not sufficient to require maxized growth rate. Less wattage goes to cuttings and veg plants. Therefore, any increased growth rate from a longer photoperiod does not translate to increased yield. For the past several years I have been using a 16/8 photoperiod in veg. In my own comparisons, I have not noticed any significant difference in rooting time for cuttings under various photoperiods from 24/0 to 16/8. I have also not measured any significant variation in yield efficiency (on a g/w/m basis) related to vegetative photoperiod. Increased phtooperiod costs more, so for the same g/w/m it is more costly $/g.


penguin

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