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lesthegringo

Encouraging basal shoots

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Guys, a couple of my nepenthes have vined, and are producing some nice upper pitchers. As there is only one growing point, of course they have stopped producing the lower pitchers, which in some cases are more showy than the uppers.

So, I don’t want to cut off the growing point, as this will stop the upper pitchers for at least a few months, but would like some basal shoots to appear, as they have in some of the other plants. Is there a way of inducing them without drastic surgery? I know that cutting the tip will give you a cutting you can root, but right now I am happy with the quantity of plants I have 

Cheers 

Les 

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There's a theory propagated by some that letting the growing stem drop below the level of the pot encourages basals.  Personally i think thats garbage and based on a misunderstanding of how plant hormones work, howver you could try it, let us know if it works.

In my experience basals form spontaneously when the main stem gets long enough (and side shoots form when it gets even longer).  Good strong light seems to help, as does a nice healthy strong growing plant.  

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Thanks Manders. I can attest to the theory being at best dubious, as my (for example ) N Sibuyanensis x Boschiana fits firmly into that category and despite being a healthy vigorous plant is not sending out shoots. Others in my collection have five or six but the stems go up  and entwine on the string lattice strung across the roof of the greenhouse. 

Curiously the biggest offender is my N Maxima,  which I always believed to be one that was renowned for sending out shoots. Instead it has a four foot vine with lovely upper pitchers but stubbornly refuses to put any other growth out.

Generally, i believe conditions to be good. Light is good, they are getting full sun (albeit through a twin wall polycarbonate sheet) for a lot of the day, temps in the high 20's and humidity in the high 70's to low 80's. With only a couple of exemptions they are flourishing, I'm getting 10 to 14 inch pitchers with beautiful colouration from some of them, and no shortage of pitchers from the others.

Oh well, I will have to let nature take its course

Les

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Les, sounds like your plants are getting much more light than mine, especially this time of year over here we might as well be in Mordor with the black ash cloud of Sauron above us. 

Maybe some plants just don't make as a many basals as others.  I know what you mean about cutting the growing tip, I hate doing it and its not always predictable how the plant will respond.  I've had some stems die right back to the roots and others grow a side shoot and carry on like nothing happened.

 

 

 

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On December 6, 2016 at 11:20 PM, manders said:

There's a theory propagated by some that letting the growing stem drop below the level of the pot encourages basals.  Personally i think thats garbage and based on a misunderstanding of how plant hormones work, howver you could try it, let us know if it works.

Well, I don't think we completely understand the hormonal regulation of this phenomenon.  But the inversion-induced release of apical dominance occurs in many plants, and it has been studied quite a bit.  It has been shown that the speed of polar transport of auxins get slowed down when the shoot gets inverted (which makes sense if you think about how auxins influence gravitropism).  Also, in the inverted region, it has been shown that the ethylene is produced.  But it appears that there are other mechanisms involved in the release.  Here is a relatively new paper about this: http://pcp.oxfordjournals.org/content/49/6/891.abstract  Here is an older paper about polar transport and ethylene: http://aob.oxfordjournals.org/content/71/3/223.short  

So I don't think that it is a completely bogus idea, manders.  I don't know if this happens with Nepenthes, though.

Edited by naoki

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Its well known that bending down a fruit tree branch so its horizontal will encourage shoots on the top side of the branch to start growing becuase auxin moves across cells to the lower side of the horizontal branch and negates the apical dominance effect.  

However, it is also well known thats plants grow perfectly well upside down because auxin is actively transported to the root area, encouraging root growth.

Therefore, the idea that bending a stem over to prevent auxin reaching the root area is clearly dubious, this was also demonstrated in space, where plants grow perfectly normally despite no gravity.

On the other hand, placing the plant on its side, pot and all, may encourge shoots on the upper side of the steam to grow, this is essentially what they did in one of the papers you mention.

"the axillary bud situated on the uppermost node of the bending region is released from apical dominance and elongates."

In Nepenthes the most likely way to get a basal to grow would be put the whole plant on its side pot and all, the point of least auxin would then be the top side of the stem, furthest away from the apex, ie the basal area.

Edited by manders

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1 hour ago, manders said:

However, it is also well known thats plants grow perfectly well upside down because auxin is actively transported to the root area, encouraging root growth.

Therefore, the idea that bending a stem over to prevent auxin reaching the root area is clearly dubious, this was also demonstrated in space, where plants grow perfectly normally despite no gravity.

Oh, I see.  You are misunderstanding the transport of auxins.  There are several ways to transport auxins.  You are focusing on the polar (directional) transport through parenchyma cells in the cortex (cells outside of the vascular cylinder).  This is relatively short-distance transportation.  Auxins are required for the branching of roots as you mentioned.  For this kind of long distance transport, auxins from shoots are transported to the root tips via phloem.  Once they reach to the root tips, then they go through the basipetal polar transport. "Basipetal" direction is the direction toward the root-shoot junction.  So auxins move toward the shoot in the root cortex.

Gravity is not required for the auxin movement between parenchyma cells.  There is a group of efflux proteins (pump auxins out from the cell), called PIN.  PIN1 is located at the cell membrane closer to the root in each cell.  This is responsible for the basipetal movement of auxins.  Then another protein PIN3 seems to move around on the cell membrane.  The location of PIN3 is influenced by gravity.  Actual gravity sensor seems to be something called statoliths (some info in this wiki).  This PIN3 mechanism is used for gravitropism in both roots and shoot.  So under micro gravity, I can see that they can develop in a normal way.   PIN3 will be located randomly around the cell membrane.  But this doesn't go against the hypothesis that gravity can be used to release the apical dominance.

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You say much but show little evidence, show supporting evidence for your 'hypothesis' and then maybe we can see if there is any substance to it. 

Gravity is used to release apical dominance in nepenthes, but not necessarily at the basal area.  If bending the stem down below the root area was releasing apical dominance you would expect to see the new shoot forming at the top of the curve, not at the basal region.  This is exactly what i see on my plants and is totally consistent with the paper you quoted.

 

 

Edited by manders

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On 12/6/2016 at 11:20 PM, manders said:

There's a theory propagated by some that letting the growing stem drop below the level of the pot encourages basals.  Personally i think thats garbage and based on a misunderstanding of how plant hormones work, howver you could try it, let us know if it works.

I'm simply stating that the hypothesis isn't garbage as you stated here, and there is some scientific background.  Sometime people make a big statement that something is bogus because they don't know enough about the topic.  I didn't know if it works with Nepenthes as I mentioned (as far as I know, there isn't any research about Nepenthes apical dominance), but your anecdotal example seems to show that it does work.  That's cool!

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Nobody is saying apical dominance wont be lost.  However, bending over the stem does not lose apical dominance in the basal area but at the top of the bend.  Hence no basals.

My guess is basals tend to form typically when the rootstock is producing enough cytokinin to counteract the auxin, cant prove it though.

Edited by manders

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Don't the shoots appeared near the ground in your example produce lower pitchers?  Or do they behave differently?

Well, auxins, cytokinins, ethylene, and strigolacton interacts to release the lateral buds, so cytokinins are involved.  But it would be interesting if the mechanism is different.

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Even side shoots arising several feet above ground level can produce lower pitchers, but they're just normal side shoots not basal shoots.

ethylene and strigolactones usually inhibit shoot development and given shoots both above and below the apex of the curved branch are still inhibited by auxin and apical dominance, seems to me the most likely candidate for stimulating basal shoots are cytokinins, produced by a healthy and growing root system.  

I like the symmetry of that actually, auxins produced by shoots promoting root growth and cytokinins produced by roots promoting shoot growth, it would a neat self regulating way of keeping a balance between roots and shoots.  Of course there will be other things going on as well.

Anyway back to the original point, it really isnt all and just about auxins which is what some folks were promoting.

 

 

 

 

Edited by manders

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In the past 2 years, i must've accidentally dropped at least 3 young plants in the 5cm-10cm diameter range, breaking their growing tip off. Everyone of them have put out at least two branch points (although no basals) as means of a survival mechanism. I'm tempted to snip the grow tip off all young plants in future ! I'll take some photos tomorrow. Bare in mind not all nepenthes branch or basal readily. What species/hybrids are you talking about ? Ventricosa and ventricosa hybrids love sprouting branches easily.

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***sorry about the weird formatting of this message, despite closing IE and logging out, every time I went to reply to this the draft message was still there and could not be deleted!***

So, the following don't seem to show any propensity to want to produce basal shoots (those with an asterisk I think would be too small, those in bold are pretty big plants)

Nepenthes (eymae x maxima) x platychila

Nepenthes (lowii x veitchii)-yellow x (boschiana x campanulata)

Nepenthes Hamata *

Nepenthes Maxima

Nepenthes Rafflesiana x Ampullaria

Nepenthes sumatrana x boschiana

Nepenthes Truncata (Ventricosa X Trusmadiensis)

Nepenthes Truncata striped x Insignis Biak

Nepenthes truncata x mira

Nepenthes Veitchii Bario

Nepenthes veitchii x burbidgeae

Nepenthes Ventricosa x Ephippiata

Nepenthes Fusca

 
 
 
 
 
 
 
 
 
 
 
 

On the other side of the coin, these all seem to produce multiple growing points (note the Bicalcarata I would have thought was too small, but there you go)

 

Nepenthes glandulifera x veitchii -H/L
Nepenthes kongkandana x veitchii-H/L
Nepenthes lowii x (sibuyanensis x maxima)
Nepenthes Maxima X Lowii
Nepenthes sibuyanensis x maxima
Nepenthes sumatrana x (platychila x fusca)
Nepenthes Truncata
Nepenthes Truncata (Lowii X Spectabilis)
Nepenthes truncata x (carunculata var robusta x merrilliana)
Nepenthes truncata x macfarlanei
Nepenthes truncata x merrilliana (a)
Nepenthes truncata-giant x alata-giant
Nepenthes veitchii x burbidgeae
Nepenthes Ventricosa X Rafflesiana
Nepenthes Bicalcarata
Nepenthes bellii x [(veitchii x maxima) x veitchii]
Nepenthes Hamata X Truncata
Nepenthes bellii x boschiana
Nepenthes Ventricosa
Nepenthes Ventricosa
Nepenthes Maxima x Vetchii
Nepenthes Spathulata X Tiveyi
Nepenthes Alata
Nepenthes boschiana x (truncata x campanulata)

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*Update*

My Maxima, Sibuyanensis X Maxima, Truncata (Ventricosa X Trusmadiensis) , Nepenthes veitchii x burbidgeae, Nepenthes truncata x mira and Nepenthes Truncata striped x Insignis Biak have all either started producing basals, or dormant nodes on the stems are budding, or both

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