Orchids seeds non-symbiotic germination ex-vitro on example of phalaenopsis

[Fernando]

Oh every times this comes up ... it is like finding the wheel for the first time ...
There are a few orchids which readily germinate in pots. Some african terrestrials, reed-epis (some, at least).
Wish you luck and a beautiful sphagnum-culture. Living sphagnum is a good thing to have. Sorry that I lost mine.

[PaphMadMan]

Of course, orchid seeds can germinate without sterile in-vitro conditions. They have done so every day for millions of years. It was the only way to grow orchids from seed when Europeans first started collecting tropical orchids, as was done somewhat regularly and successfully in greenhouses or Wardian cases.

But most orchid seeds absolutely require a symbiotic fungus to grow. The seeds consist of just a few undifferentiated cells, no organized embryo, and no stored reserves of energy or nutrients. There are some exceptions like Disa and some reed Epis, as mentioned, but they are larger seeds with stored reserves.

Those early growers had reasonably success because they had wild collected orchids filling their greenhouses, usually including the parent plant(s). Those plants brought the right fungus with them when they were ripped from their native forest, and seeds were often sown right in the pot with the parent because the growers realized that was what worked, though they didn't know why. Even if they were sown away from the parent the fungus was present throughout the greenhouse to some extent.

I won't say that what you believe you are observing is impossible, but unless the fungus is present in your sphagnum it is extremely unlikely. It can't be just any fungus, but often just a single strain or narrow range of types, and most orchids grown now are far too removed from wild collection to have ever seen the fungus, after many generations of in vitro seed sowing or mericloning. The time-line you describe is very short, especially without high nutrient in-vitro conditions, and these seedlings seem to have paired leaves with no sign of protocorms. To whatever extent they resemble Phal seedlings it is a resemblance to much older more developed seedlings than would normally be possible in the time available.

Again, I will not say it is impossible. It will be interesting to see what develops. I hope you will not be too disappointed.

[Surlair]

Originally Posted by PaphMadMan

but often just a single strain or narrow range of types

This is exactly for what I put a bet in this experiment.
As I've read they used to use a several kinds of fungus in experiments. Yet it was proven that a seed needed a specific functional strain.
And as far as the process of decomposing involves some sort of a fungus, I thought "why not - if the strain will kick in it would be a good start".

[estación seca]

Has it been shown that specific orchid species (or genera) require specific fungal species (or genera?) Is it a one-to-one relationship, or are certain fungi able to symbiose with multiple orchid species / one orchid species able to symbiose with multiple fungal species? Have many species been studied, or only a few?

[Surlair]

For the details I can only say that information that presents in a column by Knudson.


The most common plants to test were Cattleyas and Laelias.
Mr. Bernard considered that the embrio is being activated by strains of fungus that lives on orchids root, he supposed it to be Rhizoconia.
Mr. Burgeff considered that embrio was activated by specific strains of fungus Orcheomyces.
so there was no common understanding of the origin of the fungus at that time
It is said that the growth began only when specific part of embrio has been infected. And most likely - 'digested' by the embrio.

Yet, it's stated that without proper strain of fungus or due to much active fungus seeds failed to germinate.
For example, one of Bernard's experiments with fungus was as following:

The germination by inoculation is not obtained without certain difficulties. For five years I have sown seeds of diverse species of orchids in culture tubes, each of which contained ioo seeds, and these I have inoculated with Rhizoctonia obtained from the roots. Altogether, I have obtained a few hundreds of seedlings, but I underestimate when I place the number of seeds used in my
experiments at 50,000. For the majority of the seeds, the association with the fungus that I have placed in their presence has been merely passive and without effect, or impossible or rapidly injurious to the embryos.

---------- Post added at 02:43 AM ---------- Previous post was at 02:40 AM ----------

This is the part of that article that drew my attention the most:

[PaphMadMan]

Originally Posted by estación seca

Has it been shown that specific orchid species (or genera) require specific fungal species (or genera?) Is it a one-to-one relationship, or are certain fungi able to symbiose with multiple orchid species / one orchid species able to symbiose with multiple fungal species? Have many species been studied, or only a few?

It has been studied enough that it is known that some are quite specific in the symbiote range and others are more general. But many genera and most species have not been studied, though the commonly grown genera certainly have been. The tricky bit is that the fungi involved otherwise tend to be root parasites in a wide range of plants, including any orchids they don't play nice with. And any other types of fungi present are just going to use the seed as they would any other bit of nutritious plant matter. Basically the orchid has to have specific controls in place that prevent that fungus from going the rot or parasite route, and even with the right fungus it only works a certain percentage of the time. The chance of success with even the right general type of fungus from outside the home range of a species is pretty iffy, and hybrids just may not pair up with any fungus correctly.

[Surlair]

Leaves have grown a bit

[jcec1]

Could it be a liverwort?

[orchidsarefun]

Or a salvinia species?

[Surlair]

To jcec1 & orchidsarefun,

I would say "no":
1) liverwort doesn't grow on other kinds of moss unless they're close to the soil in its stage of decomposition
2) there's only one of salvinia species on our territory; it also doesn't grow in union with moss; can be transferred only with water from pond, yet I water plants with tap water only
3) not a single piece of liverwort or salvinia can survive being put in boiling water; and that's exactly one stage of how I've cleaned the medium before sowing