Pruning? How is this done?


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Manders, that is part of "Auxin Theory". It is called geotrophism. http://en.wikipedia.org/wiki/Geotropism

Dave, that has absolutely nothing to do with how auxin moves from one end of a plant to the other. The only way to stop auxin reaching the roots is snip off the growth points.

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How does that work? They are almost immediately replaced by new growing points... And the auxin flow resumes... Maintaining the shape of plant.

No. Auxin flow from growing tip to root is not affected by gravity. Turning a nep upside down or giving it a u kink in the stem is just a superstition.

Yes it is. The auxin flow is affected by several factors. I do not know how you would stop auxin from flowing down or up to the roots, but it occurs in different concentrations throughout the plant based on how much light different parts of the plant are receiving, the positions of the various parts in relation to gravity and the way the auxin flows through their tissues allows plants to achieve many different shapes. Auxin is how plants "know" which direction is up. What I mentioned about nepenthes was perhaps the stem change when they become woody? Something about the tissue changes for sure, maybe the dormant nodes start "feeling" less auxin after the stem above them turns woody, it get directed past them moreso than when the stem is still green perhaps?

Cross posting:

http://pitcherplants...scrollTo=105317

Edited by Dave Evans
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Gravity does not affect the flow of auxin from tip to root. The flow is allways in the same direction allong the stem regardless of orientation. Gravity does affect how auxin flows around a stem but not allong it. The effect in the fruit trees is because the top side of a horizontal branch has less auxin than the bottom side, but the flow allong it is unchanged. As a result more nodes are activated on the top side of the branch.

This theory of inverting neps or putting u-bends in the stem seems to be from a complete misunderstanding of 'auxin theory' as you call it, works in theory, or in fruit trees for that matter.

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Another quality of the way auxins move in a plant, is that the bottom of the bend is where advantageous roots will develop in response to the higher auxin concentration present.

As various parts of the whole plant make auxin, you would have to cut a plant down to the ground in order actually "stop auxin" from flowing to the roots.

Seriously, where do you suppose the auxin "going 'round the stem, but not down it" comes from if not the auxin sources in the growing tips and leaves? Yes, the auxin in the phloem is going to the roots, but it can get a diverted and used by the rest of the plant as well as just stay in the phloem and travel in whatever direction it happens to be orientated. How that turns other auxin effects into a myth...?

In your version of auxin theory, it should be impossible for Nepenthes to form advantageous roots without being air-layered, I.e. the phloem cut.

Edited by Dave Evans
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Another quality of the way auxins move in a plant, is that the bottom of the bend is where advantageous roots will develop in response to the higher auxin concentration present.

Its not the bottom of the bend, its the underside of a branch that has higher concentration. A normal stem has auxin in it and all allong it, regardless of orientation so yes roots can form just abbout anywhere they feel like but more likely on the underside of a horizontal stem.

As various parts of the whole plant make auxin, you would have to cut a plant down to the ground in order actually "stop auxin" from flowing to the roots.

Apical dominance.

Seriously, where do you suppose the auxin "going 'round the stem, but not down it" comes from if not the auxin sources in the growing tips and leaves? Yes, the auxin in the phloem is going to the roots, but it can get a diverted and used by the rest of the plant as well as just stay in the phloem and travel in whatever direction it happens to be orientated. How that turns other auxin effects into a myth...?

It can only be diverted around the stem, the net flow allong it continues. If it didn't the roots would stop growing and the plant would eventually die.

U bends are irrelevant as is lowering the tip, the effect you expect in nepenthes from doing this is not the same effect thats witnessed in other plants.

In your version of auxin theory, it should be impossible for Nepenthes to form advantageous roots without being air-layered, I.e. the phloem cut.

Firstly it not my theory. Auxin has two modes of transport, polar allong stems and around stems/cells gravimetric or photometric. Thats well known.

As far as adventitious roots are concerned I can only assume you havent actually read anything I wrote.

To be frank, this is just going to drag on while you come up with even more ridiculous arguments as to why turning neps upside down or putting u bends in the stem is going to to change the flow of auxin from the apex to the root even when there are plenty of published scientific papers to the contrary. You dont seem to have grasped how it works in fruit trees even.

You can keep turning your plants upside down in an attempt to disprove polar flow as long as you like it's of no concern of mine but i'm not going to waste more time arguing about it.

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You can keep turning your plants upside down in an attempt to disprove polar flow as long as you like it's of no concern of mine but i'm not going to waste more time arguing about it.

Manders, why do you keep saying something I'm not saying? The auxin is used by all parts of the plant. There is no wire connecting, like a wired network, from the top of the plant down to the bottom it is an water based solution.

U bends are irrelevant as is lowering the tip, the effect you expect in nepenthes from doing this is not the same effect thats witnessed in other plants.

Right, that is why it works, because it doesn't. Nepenthes work the same way other plants do and you haven't mentioned how they "don't really follow auxin theory". Because the version of the theory you're using is flawed. You're over-emphasizing part of the theory and watering down other parts--that's why it seems like a poor fit to you.

Did you read anything I wrote?

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Whatever Manders, You're the one that said, "The auxin theory is interesting and been used for hundreds if not thousands of years on fruit trees. Never been wholly convinced on neps as more often than not, basals seem to start growing well before the stem is long enough to bend over below the level of the pot." Which doesn't prove anything is amiss with the theory, just your understanding of Nepenthes. Auxin is also used in Drosera to affect the bending to the leaves, same for Pinguicula, they use the auxin differently than nearly all other plants. Most plants use auxin to stay "upright" and to focus the leaves toward the sun. In sundews, they use auxin to direct the movement of the traps as well! Now tell me you don't think so; so I can have another chuckle. The VFT reopens because of the way it uses auxin to signal the insides of the trap to start growing while making sure the outside does not grow. I'm sure everything is this video is mythological too: http://pandawhale.com/post/35855/mind-of-plants-documentary-on-the-intelligence-of-plants-youtube

Edited by Dave Evans
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Dave, your theory of getting basals to grow is you prevent auxin reaching the basal nodes by bending the stem or lowering the apex right? And yet bending the stem has no effect on auxin reaching the roots from the apex as its actively transported there. So can you clarify how you think it works?

Edited by manders
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I was looking in the greenhouse yesterday, and would like to offer some experimental evidence. One of my Nep vines had bent over in a nice S-shaped arc.. the growing tip was below the level of the soil, but the stem had made a nice curve in the air. New shoots grew from the top of this curve, and I didn't get any new basals. I have no idea whose case this supports.... I tried reading through this thread but got horrendous flashbacks to my states of semi-consciousness during undergraduate plant science lectures.

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Lol, both and neither...

Most likely the new shoots are far enough away from the growing tip to avoid apical dominance and the auxin is being transported to the root area in the normal way (if it wasnt you wouldn't get much root growth).

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It should probably be noted that basals (or node activation, in general) will often occur when a plant is undergoing some kind of stress, whatever that may be. A vine laying on the ground is not indicative of an ideal situation for most species..

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Whatever Manders, You're the one that said, "The auxin theory is interesting and been used for hundreds if not thousands of years on fruit trees. Never been wholly convinced on neps as more often than not, basals seem to start growing well before the stem is long enough to bend over below the level of the pot." Which doesn't prove anything is amiss with the theory, just your understanding of Nepenthes. Auxin is also used in Drosera to affect the bending to the leaves, same for Pinguicula, they use the auxin differently than nearly all other plants. Most plants use auxin to stay "upright" and to focus the leaves toward the sun. In sundews, they use auxin to direct the movement of the traps as well! Now tell me you don't think so; so I can have another chuckle. The VFT reopens because of the way it uses auxin to signal the insides of the trap to start growing while making sure the outside does not grow. I'm sure everything is this video is mythological too: http://pandawhale.com/post/35855/mind-of-plants-documentary-on-the-intelligence-of-plants-youtube

This is completely irrelevant. It has nothing, absolutely nothing, to do with the polar transport of auxin to the root system which is a regulated and active process requiring energy expenditure from the plant and which occurs even if the plant is inverted by 180 degrees.

Basal growth is much more likely to be governed by cytokinin production and the size of the root system.

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This may be of interest, there are hundreds of others like it.

"in spite of the reversal of the relative positions of the roots and shoots. No significant acropetal auxin transport could be detected even after four months growth. These results indicate that the polarity of newly formed cells in secondarily thickening internodes is determined by the existing polarity of auxin transport within the tissues."

http://www.sheldrake.org/Articles&Papers/papers/auxin/pdf/New%20Phytol%201974.PDF

"polar auxin transport is independent of gravity"

http://www.clfs.umd.edu/classroom/CBMG688R/Lec2_auxin-transp_sze.pdf

"Polar auxin transport controls multiple aspects of plant development including differential growth, embryo and root patterning and vascular tissue differentiation. Identification of proteins involved in this process and availability of new tools enabling ‘visualization’ of auxin and auxin routes in planta largely contributed to the significant progress that has recently been made. New data support classical concepts, but several recent findings are likely to challenge our view on the mechanism of auxin transport. "

http://kfrserver.natur.cuni.cz/studium/prednasky/vyvoj/FrimlPMB02.pdf

There are hundreds more similar publications.

So it seems that the evidence is that auxin is produced in the growing tips and actively transported to the root area, regardless of plant orientation. Localised active transport controls things like the gravimetric, photometric and other responses but these are highly localised with individual cells or groups of cells, ie do not prevent auxin reaching the roots.

Meanwhile, we have cytokinin being produced in the roots and this hormone encourages side shoot formation. Its seems fairly likely to me at least that once a root system gets big enough and produces enough cytokinin, this overrides the auxin which is preventing basal formation.

So it is not inverting a plant, which according to the literature has no effect, that starts basal formation, but rather the production of enough cytokinin from a large enough root system, which counteracts the auxin and kick starts basal production.

This seems more likely, once a root system is big enough to support more growth, you get more growth...

Edited by manders
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I used to have a few tanks of lowland Nepenthes. When the plants started to get too big I would air layer them, you get a new plant and prune at the same time! Also seemed to be good at encouraging ground pitchers in ampullaria.

That is a good suggestion. As of writing this I have only a memory of hearing the term "air layer" and have a vague notion of what it means. But I am going to look it up and consider doing it when time comes!

Thanks for the suggestion there, especially coming from someone with experience growing them in tanks as I am unfortunately required to do.

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"polar auxin transport is independent of gravity" Manders, I realize you're a square peg, but I never say "polar" auxin transport now did I??? What are you arguing with me about? Auxin does indeed get used by the plant in different ways when it is not in "Polar transport mode"!!!

How do you supposed this happened, in leaf tissue? :

http://www.rci.rutge...urbidgeae01.jpg

Edited by Dave Evans
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Dave its very simple, just clarify why you think auxin is prevented from getting to the basal area by inverting the stem. If there is a good explanation backed up with published evidence i might change my mind and agree with you but so far you've failed to do that.

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My advice is get as tall and as big a tank as possible. :). This was six months growth.

4137576709_546d61d455_z.jpg

Totally agree - but talk about a full tank! Wow :D

I have a really long 40 gallon tank but it isn't tall for neps, but MUCH taller than the 10 gallon in question here. It definitely is my goal to use that 40 gallon tank again as well as get a larger one someday, but I need to move out of this apartment first.

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