Tetraploid and breeding
 

Hi Guys,
My question is can a Tetraploid Plants pollen be used in hybridising?
Is Tetraploid plant sterile?
veekay

triploid ( 3N ) plants have sterile pollen. If you are lucky - I have never been - they can carry a pod to maturity.
Tetraploid ( 4N ) are not sterile and can carry a pod and be a pollen donor. You have to be careful as you can create 3N ( sterile ) plants by crossing to a 2N ( diploid ).
Its best to cross 2N with 2N and 4N with 4N, depending on what you are trying to achieve.

Is the pollen of a triploid sterile, or are they just unable to properly match the half-strands of 2N & 4N Mates?

If it's the latter, a 3N x 3N would work....

pollen of a true 3N is sterile. Sometimes a 3N plant can carry a pod. I have never been successful in that - and I have tried over 20 times with different 3Ns.
Phal Orchid World is a good example of this hit-and-miss....and occasional hit. Most of the really nice 3Ns available today are clones as cloning is the only way to mass produce them.
Of course there is no harm in trying !

Thanks!

Dumb question here, sorry...

How do you determine a 2N, 3N, or 4N plant? Genetic testing?

yes, to be 100% sure.........or

- generally species are 2N, but many are or have been colchicine treated
- the majority of phal hybrids are 3N
- 4N plants do arise spontaneously in a seedling population occasionally but most are chemically induced.
- basically the only way to propagate 3N plants is through mericloning. If your plant is a clone, then its likely its 3N
Another way - which I use extensively - but it is not foolproof, is to investigate if the potential parents have separately any registered progeny. I use OrchidWiz for this. But I have found that many progeny are not registered - I know because I have the plant !
If you really like the parents, I would encourage you to attempt a cross. Who knows, you may be successful....

To add to this, most all 3N plants can be used as the pod parent. Some are better than others. Most all true 3N plants will have sterile pollen, but some plants aren't actually triploid but somewhere between, which allows it to occasionally work as pollen parent.
As you cross a 3N x 2N (pod x pollen) you can eventually work a line of crosses closer and closer to even ploidy and thereby make the pollen fertile again. It all depends on the plant
Only way to confirm ploidy is to do a chromosome count, which annoyingly takes a lot of effort, patience, and expertise. There are some shortcuts to get an idea but these won't be confirmatory.

Seems useful to drop in a link here to the confirmed ploidy database. Note that it is far from complete.

Confirmed Ploidy Database | ORCHID VAULT

Also recommend the Big Leaf forum for questions about Phal ploidy.

Thank you for the information. I sure wish Orchidwiz wasn't so expensive!