Anyone tried symbiotic propagation?

[King_of_orchid_growing:)]

I've been looking for info on propagating terrestrial orchids through seed using the symbiotic method of sowing.

I'm curious to know if anyone's tried it and how they went about it.

[King_of_orchid_growing:)]

Just in case I wasn't clear on what symbiotic propagation meant, I mean using mycorrhizal fungi in seed sowing.

[Royal]

I've germinated Spiranthes and Bletilla "symbiotically." I did not inoculate or introduce any mycorrhiza.

Spiranthes is suspected to contain endogenous 'contamination' which makes it more difficult to disinfect for asymbiotic germination, but facilitates symbiotic germination. Bletilla seed actually contains some endosperm and is therefore equipped to germinate somewhat more conventionally(to a certain extent).

I've tried it a few different ways, peat moss, sphagnum moss, cardboard, brick, soil, water, bark, etc. The soil, peat, and sphag worked the best. The cardboard and the brick methods didn't work for me at all. I found those somewhere online, and I think they were used for tropical epiphytic species. The challenge is keeping moisture up while keeping mold out.

[Andrew]

I'm assuming you're meaning symbiotic germination in the pot rather than symbiotic germination in vitro. I've germinated several genera of Australian terrestrials in the pot. Germination rates are much lower than with asymbiotic germination. If you get germination, don't expect much more from a pod of seed than enough to fill the pot. By contrast, Disa uniflora, which apparently contains endosperm in its seeds, will easily form a dense mat of protocorms when germinated in a pot without the parent.

While genera like as Spiranthes and Microtis readily germinate as weeds in other pots, more often than not terrestrials have more specific fungal requirements so generally I prefer to germinate the seed in the parent's pot. I sow seed on the surface of the pot at the beginning of the growing season so that the seedlings have plenty of time to develop before dormancy.

Germination is only the first part of the problem. Seedlings can easily rot or dry out so care must be taken with watering. In the case of tuberous terrestrials, assuming the seedling managed to develop a tuber before dormancy, the tubers are usually so small that they easily desiccate during dormancy. However, the tubers are just as prone to rotting from excessive moisture as mature tubers so its a challenge to get them to come back the following season. For this reason I prefer flasking seed I actually care about but for the average (esp. non-colony forming) terrestrial orchid in my collection I'll often sow the seed in the pot and see if anything comes up.

[Royal]

Andrew, Good tips. Thanks for sharing!

[bonsai1504]

where do you get the fungus for symbiotic germination?

[Royal]

Sometimes it's in the seed already (endogenous). Sometimes you utilize any existing microbes by sowing in the container with the mother plant (like Andrew described). Sometimes it's just ambient.

[King_of_orchid_growing:)]

Apparently alot of people in Europe who grow Dactylorhiza take a bit of rootstock from a mature plant and they try to isolate the fungus. I don't know how they do this though..

[Royal]

Originally Posted by King_of_orchid_growing:)

Apparently alot of people in Europe who grow Dactylorhiza take a bit of rootstock from a mature plant and they try to isolate the fungus. I don't know how they do this though..

I read somewhere about taking a root tip, pulverizing it, and mixing with water. Kind of a inoculate stock solution.