Why is it so?

[Stone]

Why is it that 1 out of 2 seemingly identical plants (bellatulums in this case) which are both doing perfectly well for 2 or 3 years, suddenly loses all it's roots while the other keeps charging ahead as if everything is peachy?
I mean they where both from the same flask, exactly the same size and treated exactly the same.
They were kept as a pair always next to each other and everything was identical! (mix water feed light air everything) One slowly started to go a bit pale so I checked the roots and there was almost nothing left. I checked the other one and all the roots are perfect. What the..?
There must be a reason but I can't see it for the life of me...

 

[Ozpaph]

**** happens????????????

 

[PaphMadMan]

Even with full sibs they aren't genetically identical, so identical treatment doesn't mean they both got what they needed.

But did they really get identical treatment? Is the potting mix so perfectly uniform that one couldn't have been slightly wetter or drier over the years? Did one get picked up and poked and prodded more? Or one root damaged at repotting or by a random slug could sent one plant on a different trajectory? I could go on. Living things, real world...

 

[gonewild]

You don't want to hear this but surely you must expect it. oke:

Basically this is the type of health problem we have been arguing about for years. A problem that decreases or stops with the reduction of potassium. Loss of an individual plant for no reason... does have a reason. It may not be restricted to only potassium and involve other nutrient well.

It's probably caused by certain plants having less genetic tolerance to being "obese". If you can determine a pathogen was actually responsible for the root death then the argument would be whether the pathogen was able to over come the roots because of excess potassium or other nutrients for some reason.

You asked why, so at least consider the results of people that been experimenting with low K.

 

[NYEric]

snails!

 

[Stone]

Well apart from the extremely low possibility of snails, nothing of the above has anything to do with it. Including genetics. It's just not possible that tiny variations in genetics could have such an affect given the adaptability we know about.

When I say no roots I mean they were all still there (except the tips) but they were all rotted off while the other plant's roots were all nice and plump.
Perhaps the only explanation is some unseen pest as Eric suggests??
When I have similar problems with other plants I can usually work out why by looking at the root environment. More often than not the mix does not dry fast enough and the roots go but this is not the case here.

Lance, thank you for the ''K thing'' but in my mind I have determined without the slightest doubt (I mean none at all!) that potassium has nothing to do with anything. If you want further evidence, look at the habitat of rothschildianum.
http://www.google.com.au/url?sa=t&r...=48768&usg=AFQjCNHO3O7-_nGuqejJ5z5_yqW04DVT4w

It has very low K yet this species absolutely thrives in cultivation with plenty of K....and is long lived too. K just does not affect plants very much unless it is completely out of balance for an extended period.

 

[Stone]

**** happens????????????

Yes true Oz but is that good enough? Don't we need some working theory to improve our culture????????
I know experience is the main thing and with Paphs it is precisely 5 years! (and mainly with seedlings) I've had to re-learn a lot.

 

[abax]

I agree with Ozpaph. It ain't an explanation, but helps when you have
a conundrum with infinite possibilities. The same thing has happened
to me. My resolution is to suck it up and get on.

 

[Stone]

Hmmm, perhaps I should have asked ''what could it be''?
I was hoping for some possibilities form experienced growers which I could either investigate or dismiss. These 2 plants were twins and treated identically in every way. Where's the lateral thinking? Sucking it up will lead to the same in the future won't it?

 

[naoki]

Are you using Tanaka's method for those P. bellatulum as you mentioned before? Did you check the EC of pour through for the healthy vs unhealthy?

Could it be that the balance between plant and mycorrhizae is on a fine line? "Mutualism" sounds like a peaceful term, but actually they may be trying to exploit the partner. We know that Paphs have fairly strong association with fungi in nature, and they are isolated from pot culture. I forgot the species of fungi associated with Paphs, but they may have pathogenic attributes (kill living tissues) like Rhizoctonia. So the fine balance tips a bit by small stress in plants, and the fungi may get the upperhand. The fungi may feel that the host isn't giving enough, so they start to eat the host's roots. Then this bad feedback accelerates. It is probably just sci-fi, and it probably won't go anywhere.

 

[Stone]

Are you using Tanaka's method for those P. bellatulum as you mentioned before? Did you check the EC of pour through for the healthy vs unhealthy?

Could it be that the balance between plant and mycorrhizae is on a fine line? "Mutualism" sounds like a peaceful term, but actually they may be trying to exploit the partner. We know that Paphs have fairly strong association with fungi in nature, and they are isolated from pot culture. I forgot the species of fungi associated with Paphs, but they may have pathogenic attributes (kill living tissues) like Rhizoctonia. So the fine balance tips a bit by small stress in plants, and the fungi may get the upperhand. The fungi may feel that the host isn't giving enough, so they start to eat the host's roots. Then this bad feedback accelerates. It is probably just sci-fi, and it probably won't go anywhere.

Thank you naoki. This is one possibility I had not thought of but I have read that rhizoctonia (spelling?) can be both beneficial myco or pathogenic killer!
They are still too young to go into the large ''Tanaka style'' potting system. I do have one concolor in a large bowl doing very nicely so far. The other brachys will go in when/if they reach the vigorous stage.

 

[PaphMadMan]

...It's just not possible that tiny variations in genetics could have such an affect given the adaptability we know about.
...

A tiny variation in genetics is the reason one human sibling lives a long healthy life and another dies from complications of cystic fibrosis or sickle cell anemia, though they may seem healthy right up to the moment symptoms first occur. Adaptability has nothing to do with it, and that is just 2 examples from one species. It could be the cause behind a different reaction to a potential pathogen (Rhizoctonia) or environmental trigger (the K thing), as with pneumonia or oxygen stress in those human examples. Any species, any stage of life, any time.

 

[gonewild]

A tiny variation in genetics is the reason one human sibling lives a long healthy life and another dies from complications of cystic fibrosis or sickle cell anemia, though they may seem healthy right up to the moment symptoms first occur. Adaptability has nothing to do with it, and that is just 2 examples from one species. It could be the cause behind a different reaction to a potential pathogen (Rhizoctonia) or environmental trigger (the K thing), as with pneumonia or oxygen stress in those human examples. Any species, any stage of life, any time.

:clap::clap:

 

[Ozpaph]

I also think the two sibs are more genetically different that they appear phenotypically.
There pot environment may also be more different than externally obvious - more bark, less stone, more fines etc etc. Check the pH, salt levels etc

Subtle differences lead to different outcomes. eg you and your sibs have the same parents and bought up in the same house yet I bet you are all quite different - just like your 2 plants.

ps - nice Prof Julius Sumner Miller reference!

 

[Stone]

A tiny variation in genetics is the reason one human sibling lives a long healthy life and another dies from complications of cystic fibrosis or sickle cell anemia, though they may seem healthy right up to the moment symptoms first occur. Adaptability has nothing to do with it, and that is just 2 examples from one species. It could be the cause behind a different reaction to a potential pathogen (Rhizoctonia) or environmental trigger (the K thing), as with pneumonia or oxygen stress in those human examples. Any species, any stage of life, any time.

All very interesting but unfortunately completely irrelevant in this case. It makes about as much sense as blaming your car accident on your mother's parents.
It has nothing to do with genetics. It is an environmental issue. I have grown countless (many, many thousands) of plants from seed all with genetic variability. All survive given proper care. I have deflasked hundreds of orchids over the years. Usually they all survive exactly due to the adaptability I mentioned. The ones that don't have been sloppily treated when still vulnerable to attack by pathogens. Many times (in fact very often) a plant will lose it's roots or develop leaf diseases while it's neighbour which is a division of the same plant and genetically identical does not. The loss of this particular plants roots due to a genetic factor is so infinitesimally small it does not bear consideration. This genetics nonsense needs to be jumped on from a great height.

 

[PaphMadMan]

So, genetic variability can't contribute to differential survival? I didn't realize I was dealing with an evolution denier. There's no basis for discussion so I will refrain from further comment.

 

[naoki]

That's a bit exaggeration, Kirk and Mike.

For Kirk's point, there could be genotypic difference, but selection acts on phenotypes. Phenotypes are determined by both genetics and environment. So even a particular person has a great healthy genotype (we human carried quite a lot of deleterious mutations BTW), if he/she doesn't have healthy life-style, the person might die early. I'm pretty sure that Kirk knows this, though.

Also, I'm not sure if genetics has nothing to do with this as Mike said. If it is already highly inbred (e.g. artificially selected for a long time), then the genetic variation within sibs may be low. But if it is self-fertilized progeny from habitually outcrossing species, you expect quite a bit of variations. Some do very well while others are homozygous for many deleterious mutations, and show inbreeding depression. When we deflask, we frequently see quite a bit of variations. My gut feeling is that quite a bit of variation is due to environments (e.g. position in the flask, and who was its neighbor), but some are possibly due to genetics. But Mike is trying to say that since it has been growing ok for a while until recently, it is unlikely to be genetic. It is probably likely. But you never know when the inbreeding depression is expressed. There are some early acting and late acting inbreeding depression. In other words, some mutations are expressed at a certain life-stage. What Kirk was saying is that some of these deleterious effects may not be observed until they are challenged. Mike might says that his is not self-fertilized, but similar situation can happen in outcrossing (but less likely to see extremes in OC due to the masking of deleterious genes).

Finally, genetics can be environment dependent as we all know. Some deleterious genes may not be deleterious in another environment. A plant with immunity problem can be completely ok if it is grown completely aseptically. So by providing certain environment, more plants may survive well even if there are some mismatch between the genotypes and environment. As a tangential note, this is related to the big problem of ex-situ conservation (unconscious selection for cultivated environment and dysfunctional flowers).

But I agree that it is more productive to figure out how to change culture environments than giving up.

 

[Ozpaph]

Mike, you did ask for 'theories'. Genetics is one aspect.

 

[Stone]

What is wrong with you people? Too much theory and not enough practice??

I think I've been growing things for long enough to recognize the difference between sudden root rot caused by some (presently unknown) environmental factor and some nebulous genetic trait suddenly manifesting itself and resulting in this problem. The survival rate of seed grown plants is always almost 100%. Any genetic predisposition to pathogen attack will show up within a short period of time (except perhaps under sterile conditions) Certainly not on a healthy strong plant after some years! I don't know why this even needs to be discussed.

Here are some seed grown plants of various species. All healthy plants which survive the first year from seed (99.9999999%), will continue to do so unless some environmental factor intervenes. Those that do not - due to a genetic factor - invariably succumb shortly after germination and after exposure to the pathogen or other environmental factor. Certainly not after some years of vigorous healthy growth!

charlesworthii


charlesworthii


Rhyncostele bictoniense


Laelia jongheana


Dendrobium nugentii


Spathoglottis


Laelia milleri


roths


stonei


Euchile mariae



Dendrobium jenkisii

 

[Stone]

Some more

Acer palmatum


Cliveas


More cliveas


Coastal tea tree


Paperbarks



Need I go on?
All these are grown from seed. All genetically individual. Some are selfings, some are outcrosses. BTW, I don't remember losing any of the orchid seedlings out of this lot at all which shows that genetic weakness is already rare by the time you receive the flask from the lab. The chances of losing the odd plant from a batch of clones is (practically) the same as from a batch of seedlings.

All are growing well. So show me all the sudden death appearing after a time caused by genetic factors.
The truth is it is not there, or if it is, it is so rare that I can honestly say I have never seen it in 35 years.
This reminds me of a certain theory regarding a certain nutrient element.......