hybrid pollination

[neophyte]

Hi, this question has probably been asked before, but I've been wondering why a lot of hybrid/cultivars can't produce seed pods. I don't have a lot of experience pollinating orchids, so maybe I just haven't given the orchids the correct conditions to create seed pods, but I've only managed to produce seeds with one phalaenopsis that had solid pink petals (ie., no patterns on petals, which seems to be more common in hybrids/cultivars). With any other of my orchids (I've only tried pollinating phalaenopsis), it just doesn't work. I noticed that those two flap thingies protecting the stigma are usually open but after you pollinate they close together to prevent other pollen sacs from pollinating the plant (which is cool), and usually when I try to pollinate my other orchids the flaps do close, but nothing beyond that happens -- the flower just aborts . Why does this happen?

edit: When I said pollination, I meant I took pollen from one flower of the plant and put it on the stigma of another flower on the same plant (or took pollen from one flower and put it on that flower's stigma)

[Ray]

There can be a number of reasons a cross won't "take", including ploidy, size, age and overall strength of the plant.

Orchids are diploids, just like people, with pairs of chromosomes. Sometimes, whether natural or induced, that is doubled to produce tetraploids that tend to have "better" flowers. If a diploid and a tetraploid are crossed, the offspring may be triploids, and those cannot breed with either of the others.

If the plant's flowers are distinctly different in size, the mismatch might hinder the pollen reaching the ovary.

Pollination seems to occur most reliably if done a couple days of a flower opening.

A tip you might try: Using a toothpick, "mash" the pollinia on a piece of waxed paper to better expose the pollen within before applying it to the viscidium (it's not a stigma).

[estación seca]

Ability to accept pollen varies over the life of an individual flower. You might have been pollinating too early or too late. Go to the library and read Joe Arditti's book on orchids.

[neophyte]

Thanks for the replies!

@Ray thanks for the tip! By the way, I read that Cavendish bananas (the ones you get at the supermarket) are actually triploid and all Cavendish bananas are actually cuttings from one ancestral plant. And now there's a banana blight that's killing the Cavendish bananas and since they are triploid and can't reproduce, they all have the same DNA and have no resistance. :O

@estacion seca thanks for the advice! I'll go check out the book.

[Fairorchids]

In Phalaenopsis, a standard diploid plant (2n) has 38 chromosomes. As Ray mentioned above:

• 3n is normally sterile.
• 4n exists too, which will not easily breed with a 2n.

And, have just seen a notice that at least one 8n has been identified.

If you are selfing, this should not be an issue (unless the plant is a 3n).

In certain other genera, the chromosome count varies from species to species (and sometimes within the species). This significantly limits the seed production (especially in Paphiopedilum).