Does fungal infection induce keiki production?

[SG in CR]

I was wondering if other people have observed something that I've noticed.
I've had several times where the base of a p-bulb got infected with something, I'm guessing fungus, and the p-bulb developed a keiki up on the still healthy part of the p-bulb. Most of the time the roots/base will start a new shoot as well. I've had this happen now with Aspasia, Prostecha, Mormodes and Catasetums. Which is great in a way, I got to start a new plant.
But if I take a sterilized blade and cut the same sort of piece off it will slowly wither away over the course of months without ever making any new growths. It seems to me that the infection somehow is giving the plant a signal to start growing a keiki.

[SG in CR]

Here's an example I just pulled off a Prosthechea cochleata just now. It got some sort of an infection near the base of the bulb and in response it produce a keiki.

Now if I were to just cut off a psuedobulb I don't think it would ever produce a keiki. Nor would it ever produce one on a healthy p-bulb. Seems to me that the infection somehow induced it.

[Roberta]

Orchids want to survive... Also, sometimes when a plant is dying, it will produce a flower spike in an desperate attempt to reproduce before it dies. (Phals definitely do this) And often a shock (such as a rapid temperature change) will induce blooming, basically frightens the plant. (This approach is used by commercial growers to start the spiking cycle on Phals to get them to be in bloom at specific times such as holidays).

So the loss of the pseudobulb to infection may very well trigger this "fear" response to produce a keiki. I do suspect that there needs to be some part of the plant that is still healthy driving the process, so just cutting off a pseudobulb probably won't work.

[SG in CR]

Originally Posted by Roberta

I do suspect that there needs to be some part of the plant that is still healthy driving the process, so just cutting off a pseudobulb probably won't work.

That's the part that I find strange. Every time I've observed it, the keiki starts forming when the p-bulb has lost it's connection to the rest of the plant. The entire bottom part of it is dead by that point. The advance of the dead portion is slow but steady up the -p-bulb. Yet I've cut off 90% of an old but healthy Mormodes bulb thinking it would eventually develop a new plant on one of the eyes and it just sat there doing nothing for nearly a year till it finally just shriveled up despite being in better condition initially than the ones with some sort of infection.

[Roberta]

In nature, there is nobody running around with razor blades... plants have evolved strategies to survive. You may not be successful trying to improve on nature.

[SouthPark]

Originally Posted by Roberta

Orchids want to survive... Also, sometimes when a plant is dying, it will produce a flower spike in an desperate attempt to reproduce before it dies. (Phals definitely do this) And often a shock (such as a rapid temperature change) will induce blooming, basically frightens the plant. (This approach is used by commercial growers to start the spiking cycle on Phals to get them to be in bloom at specific times such as holidays).

So the loss of the pseudobulb to infection may very well trigger this "fear" response to produce a keiki. I do suspect that there needs to be some part of the plant that is still healthy driving the process, so just cutting off a pseudobulb probably won't work.

I agree that it is likely a survival 'mechanism' --- a system response ----- the orchid's biological system starting up some other cellular processes when other cells are not functioning, or not functioning normally in particular ways.

As orchids don't have brains ------ and aren't humans or animals with thought processes ----- then that sort of response is not due to 'fear' or 'fright' or 'want/wish/desire' to survive etc. It is only due to the orchid's own biological system response --- a process that developed from evolution.

[SG in CR]

Originally Posted by Roberta

In nature, there is nobody running around with razor blades... plants have evolved strategies to survive. You may not be successful trying to improve on nature.

I guess I'm just a bit surprised because the trigger for keiki formation isn't the stress of a dying p-bulb itself (if that were it, the cut healthy ones would do it too) but seemingly the infection is a necessary part of triggering it.
I wasn't really looking to improve upon nature in any sense other than maybe propagating a plant by cutting off a piece. I just thought it an interesting observation that an infection can drive a plant to produce keikis that normally doesn't.

[Shadeflower]

SG, I think you are looking into the infection bit too much. To me what you have observed makes a bit of sense.
Fungus needs a high humidity to thrive so it forming shows it is in a high humidity environment which is what triggers keiki formation on a pseudobulb that has lost its roots.
When a pseudobulb gets attacked by a fungus it becomes soggy. This will further encourage any remaining live tissue to start forming a keiki.
The question is whether the keiki can become big enough in time.
I honestly don't think the stem getting infected is what triggered the keiki formation. It's more the plants mechanism to want to survive and a high humidity will enable it. If the stem is not kept humid enough it won't form a keiki.
I have a stump that has a keiki on it at the moment that I'm not going to bother keeping alive. Whenever I spray it, it grows a bit but if I don't keep spraying it it won't make it. If I did start keeping it so humid that mold would start growing then I am pretty certain it would also encourage a keiki formation but it has less to do with an infection or mold growing, more the humidity which is why trying to save rootless orchids is so tricky, they need high humidity but high humidity also encourages mold and fungus to grow.

[estación seca]

Most plants have many extra meristems that never grow. Hormones produced from the growing point of plants inhibit these other meristems from growing. If the base of a psudobulb dies, and all the growth tissue there is gone, that may allow a more distant meristem to escape the hormonal inhibition, and start growing.

[SG in CR]

I should maybe elaborate, I have had nearly all my orchids mounted in trees and palms around my house till recently when I started potting some seedlings that had popped up where I didn't want them and a few plants I bought that I don't have a good place to mount. Mounting in trees is great except for the fact that they tend to drop branches and fruit that can hit an orchid and break stuff off. I've had it happen enough to have tried dozens of times to salvage the broken off parts. For some species it works, like quite a few Epidendrums will gladly regrow from a broken off stems.
But for most will not if there is no root tissue connected. I'll put them in a somewhat shaded spot often at the base of an orchid I keep watered when the weather is dry. and they will remain green and supple for quite a long time. Despite that they eventually succumb to not having a root system and start shriveling up and die. Yet strangely enough without any pampering from me these p-bulbs that are slowly rotting away from the bottom ( the rest of the plant seems unaffected) will produce keikis.

Originally Posted by Shadeflower

SG, I think you are looking into the infection bit too much. To me what you have observed makes a bit of sense.
Fungus needs a high humidity to thrive so it forming shows it is in a high humidity environment which is what triggers keiki formation on a pseudobulb that has lost its roots.
When a pseudobulb gets attacked by a fungus it becomes soggy. This will further encourage any remaining live tissue to start forming a keiki.
The question is whether the keiki can become big enough in time.
I honestly don't think the stem getting infected is what triggered the keiki formation. It's more the plants mechanism to want to survive and a high humidity will enable it. If the stem is not kept humid enough it won't form a keiki.
I have a stump that has a keiki on it at the moment that I'm not going to bother keeping alive. Whenever I spray it, it grows a bit but if I don't keep spraying it it won't make it. If I did start keeping it so humid that mold would start growing then I am pretty certain it would also encourage a keiki formation but it has less to do with an infection or mold growing, more the humidity which is why trying to save rootless orchids is so tricky, they need high humidity but high humidity also encourages mold and fungus to grow.

Might be that I'm reading too much into the infection. But my climate is fairly humid from about June to December and only dry enough to need to water my plants from about March to May. So humidity shouldn't be to limiting factor on the cuttings I've tried to get to grow new plants. And the fact that they take the better part of a year to finally die makes me think that it's not that the plant doesn't have the resources to produce a keiki, it's that it never gets triggered to do so.

Originally Posted by estación seca

Most plants have many extra meristems that never grow. Hormones produced from the growing point of plants inhibit these other meristems from growing. If the base of a psudobulb dies, and all the growth tissue there is gone, that may allow a more distant meristem to escape the hormonal inhibition, and start growing.

Maybe, though I get the impression that it's not only the active growth that inhibiting the extra meristems from breaking dormancy but they need some sort of trigger. My hypothosis is that something about dealing with an infection might be that trigger. I might be wrong about the connection though. It seems one else has made this observation.