Fail to cross orchids
 

Hello,

I have tried to pollinate phals and cattleyas and soon after the flowers will wilt and ovules will be swollen. However, swollen ovule will go brown shortly after and the spike will die off before it forms a seed pod.

I was wondering if someone can point out what I am doing incorrectly as it seems that pollination did occur but formation of a seed pod is always abandoned by the plant. Is there a general rule such as pollination on one flower per spike and etc. Thank you.

Assuming you have followed basic rules ( like phal to phal, fresh pollen and placing the pollinia correctly in host ), then you probably have a ploidy issue. Generally speaking phal species are 2N and these can be crossed, some with extreme difficulty. You can see results of crosses here - called primary hybrids:
Phalaenopsis Orchids : species and primary hybrids

However hybrids are different in that you can get 2N 3N 4N ploidy. Genetics is complicated and you can research ploidy limitations further. Generally speaking you cannot cross a 3N hybrid with another 3N hybrid and get germination. These phals are mericloned to obtain hundreds of offspring, if worthwhile. No seed propagation is possible. You should research the background of your phals ( orchidwiz , RHS) to try and figure out the ploidy. If your phal has registered offspring, then its safe to say it is either 2N or 4N. In very rare circumstances will a 2N crossed with a 3N result in germination. Same with 4N x 3N
All my crosses have been with phals but I am sure the same principle applies to cattleya crosses. I learnt the above the hard way as there is not much info about this on the internet. Good luck.

Thank you for your reply!

I suspected it was a triploid issue but wasn't sure since I failed in a few different hybrids. But the suggestion to see if hybrids had produced offspring previously on orchidwhiz is a great tip.

I was wondering if I can ask a few more questions since you have experience in crossing phals,

- what do you think is the maximum number of flowers you can pollinate on a single spike or allow to develop into seed pods.

- if one of the parent is a triploid, would I still see a swelling of the ovule?

Thanks!

I've done up to 3 on phals, bearing in mind each pod can produce thousands of seeds. You can do reverse crosses at the same time too.
The bad news is that sometimes the pods can develop fully, even dehisce and still contain no seeds. Another issue I've just had with 2 pods - only 10 seedlings are barely surviving. This is something new for me as I generally get my hybrids to bloom within 1 year of deflasking. If you look at the propagation thread you may find a couple of examples.
I don't have the definitive answers to genetic issues and it seems very few people do. I have contacted growers in Taiwan and had no response.