Give it a shot! I think you may need embryo rescue/ovule culture/or ovary disc culture to make it work though. I have been using these techniques to obtain wide lily crosses and have some tissue cultures from a cross of Orientals x an Easter lily hybrid. I often use intrastylar pollination to help get the pollen tubes down to the ovary. Cut off the long style just about an inch above the ovary. Next, cut into the inch nub long ways about half an inch. Next pry open the halfs of your cut style and fill it with the desired pollen and some stigmatic exudate. Then wrap it together with a little parafilm to keep it from drying out. Incompatible crosses often have slowed pollen tube growth and this technique can allow for pollen tubes to reach the ovules and for fertilization to occur. Sometimes this is enough to obtain viable seed from wide crosses. Sometimes fertilization occurs and then the endosperm fails and then the embryo aborts for lack of a food source. This is where tissue culture comes into play to try to rescue the embryo before it dies. I prefer ovary disk culture since it's relatively easy, even though some say you can recover more embryos with direct embryo rescue. I surface sterilze the ovary and then put thin (4mm) cross sections of the ovary onto media (basic MS salts and vitamins plus 9% sucrose, 1mg/L NAA, and 7g/L agar, pH'd at ~6.0). The ovules swell and those with viable embryos can swell enough and break through the ovule. THen I just subculture those that grow and acclimate them out.

The cross you are proposing seems very wide to me. I have had trouble getting good seed set using normal pollination with L. formosanum x L. longiflorum. L. formosanum is probably Easter Lily's closest relative.

All the LA hybrids (L. longiflorum / asiatic) and new LO (longiflorum / oriental) hybrids originally need some sort of embyro rescue technique to recover hybrids. In future backcrosses it isn't always necessary.

Good Luck and let us know what happens!

Sincerely,
David

Thank you