I will be posting follow up pictures and discussion regarding embryo culture on R.gigantea X R.longicuspis (WEC run #4) here.
If you want to see how this run was started, please click on the link below:
Link: www.rosehybridizers.org/forum/message.php?topid=33780&rc=38&ui=2829830532
I have had trouble with the water in the tray causing the h+p media to go gluggy, so I got rid of the water tray, and abandoned the blue nursery pots, and instead used four foam cups with no holes in their bases.
I opened all the pots, removed the embryos and kept them in a glass of tap water, whilst I recombined all the media and added dry perlite to it, until it was better aerated.
I added the recombined media into these foam cups, and resowed each embryo on the surface of the media, one per cup. I then sealed the cups with cling wrap secured with a few rounds of adhesive tape.
The embryos looked very thread like and extremely delicate. I sure hope I didn’t injure them in these transfers.
Oh yeah, one embryo was no good, I threw it out. Four remain now.
Here is how the new/current WEC set up appears, quite neat and easy to place anywhere away from direct sunlight / heat, indoors:
Here is a top view through the cling wrap of the above cup. This R.gigantea X R.longicuspis embryo is greening up:
All except the green one shown above have rotted…it is very likely that the h+p media is creating a clogged up environemnt which they clearly hate.
Since I have kept spare achenes in case this were to happen, it is all good!
I will redo the run, using pure perlite and see if I can seal the foam cups with cling wrap and tape without too much embryo shifting in this very mobile perlite media ( I will try very gentle taping LOL).
Here is the greened up one, in its new perlite-only media:
I guess if this one does ok, I would at least have met my objective to get one plant!!
So… ya ready for vermiculite yet?
I hear what you say, and it is perfectly logical.
The main reason I chose to try the ordinary grade perlite with the foam cup, is because run # 1 started off very well doing this except I used a glass cup which was a whole lot easier to seal off (compared to the foam cup) without disrupting the media+embryo within.
But with a little extra care it turns out the foam cups are able to take gentle taping of the cling wrap without too much embryo displacement.
I have also found a different brand of seedling mix compared to the one which had fungs gnats in it, which I hope will be safe to use for these embryo-seedlings once they look big enough for transfer.
At least that is the plan, at this minute…
Again, this is the pic of the surviving one, which I posted further up, and which was accidentally removed…LOL!!
Here is the greened up one, as of a few minutes ago:
SCALE 1 gap = 1/16 inch.
It has rotted cotyledon tips, and looks unwilling to root past this rudimentary stage. All its siblings were covered in hydrocrstal goo, and suffocated. I am not sure if this one got a lesser dose of that gunk, and almost made it…near enough but not good enough!!
I made sure to leave heaps and heaps of remaining seed from this cross, in case such a disaster happened.
If I have learned anything from a few years of doing embryo cultures, the most importatnt thing I have learned is to sample and test run a small fraction of the total seed in an embryo culture run, not do the whole lot at once.
I learned this hard lesson only about 8 weeks ago, when hundreds and hundreds of seeds were posted to me from USA, and 99.999% all went to waste because of fungus gnat, and subsequent emergency transplanting which failed in the heat of sumemr…Instead of having hundreds of seedlings from hundreds of great embryos, I got two!!!
Lesson learned…any single little thing that can go wrong in rose embryo culture can lead to a catastrophic wipe out, from getting the water balance perfectly right, down to very silly things like being unaware of potential predatory critters!!!
Yup, kinda like doing hair dye. Use a test piece first… or suffer fate 
Soooo, as I run through right now and open up more of this wonderful dry seed, I thought I’d take a few pix to show details.
Here is how dry these are (it is a qaurantine requirement to receive rose achenes dried from overseas):
SCALE 1 gap = 1/16 inch.
Here you can see two non-viable seeds (on the left and centre), and the one on the right which is still in its woody covering looks like it could be potentially alive …it reminds me a bit of an Egyptian mummy just discovered in its sarcophagus LOL:
Doing WEC on dry seed versus fresh seed is a totally different ball game, with a totally different degree of difficulty IMO.
Embryo culture of dry seed in my experience is the most challenging to succeed in, as the drying causes various physiological changes. One day, I might write a separate thread on this topic, as I think it is very interesting.
Here are the rose seeds with their papery coverings:
After a few hours of them soaking in water, I’ll remove their papery coverings.
Then, depending on what state they are in (white or waxy or inbetween) I’ll try and guess the optimal water soaking regime.
Stay tuned…
Here are all the embryos that resulted after removal of the papery coverings of the above seed:
This time, I will review them after they have soaked for 24 hours total since the time they were extracted from the woody pericarps.
Now, at just a few hours past ~24 hours of this seed entering water and having its papery coverings removed, some of the embryos are starting to open cotyledons, but only very slightly.
I know five of them came out of their papery testa looking to be the dormant/dry “waxy type”, but I am pleased and rather surprised to see these immediately became “white type embryos” almost as soon as they hit water.
All these are good signs IMO.
It is hard to guess how long a water soaking (imbibition) is optimal for this group… because these all continue to look like “white type embryos” and not “dormant/waxy” types, I am not going to have them in continuous water immersion for too many days on end, to be sure!
Here are ten of these 14 embryos, after a complete 3 day water soaking (water changed daily):
These represent the best ten out of the original 14 submitted to the 3 day water soak. The remaining four which don’t quite have that optimal pearly white look, are likely from the group of five that were “waxy/very dormant” at the time of extraction. On the assumption this is true, I am letting these four have a longer water soaking time, hoping this will bring them to a more uniform pearly whiteness (and hence hopefully lesser dormancy).
Here is the sowing set up:
The inside of the cling wrap was also misted, to help distribute more humidity to the upper zone/surface of the perlite (where the embryos are sown).
There are two sowing cups, each cup has five embryos sown in it (around the circumference of the cup).
That’s such a fun cross. I would love to see some mature plants from it. Anyone ever use Cooper’s Burmese?
LOL…an embryo-seedling would suffice at this point.
Actually, since sowing this lot of embryos in perlite yesterday, one of them has already started to green up… a good sign this early on in the sowing.
N.B… I have also realised that cling wrap+glass cups+elastic bands works just fine, no need to use adhesive tape. 
You can easily release the band, re-wet the inside of the cling wrap and spray a bit of mist on the perlite surface (whenever you require) and then reapply the band, too easy!!
(with foam cups, the problem was that foam and cling wrap do not naturally “stick” together like glass and cling wrap do).
Here is the one which is greening fast:
Actually I just noticed there are other greening ones, as well.
The same embryo as above, 24hrs later…
Looks ok so far.
This is the sort of progress is more prevalent in embryos form fresh seed than from very dry seed, IME.