Because the original thread on JAR EMBRYO CULTURE etc. has grown so long that it is difficult even to browse it, I start a new thread here and paste the description of the method by GEORGE, SYDNEY, AUSTRALIA. Hope you don’t mind, George!
Thanks, George, for posting your method! And to all others for making useful comments and suggestions. JEC has already revolutionized my very small-scale amateur hybridization. In my cold climate in Finland it’s hard to get hips ripening well and those few that do always show disappointingly poor germination. I was already giving up the whole of rose hybridization and pursue only rhododendron hybridization (which is FAR easier) when I came across your post about jar embryo culture. I immediately gave it a try and now, even though I’ve processed just a few dozen seeds, I have several small seedlings from two crosses (Duchesse de Montebello X John Davis, Golden celebration X Klaus Groth) growing on my window sill! I can’t wait to get seeds from my other crosses processed! I’m very excited about getting seedlings from my Alfred Colomb X Flammentanz cross. Hoping for some fiery reds!
So, thanks again, George!
Jukka
Helsinki
Finland
Quote from a previous post by George, Sydney, Australia:
"When I first started playing around with this idea of mine (early 2009), of course I was slicing into and squashing a lot of embryos. In order to get high percentage intact embryo extractions, I realised it was important to define the long axis of the seed with a few initial key slices. Sometimes it was easy to guess, other times a little more slicing was required to define the long axis orientation of the seed within the achene.
After you get the long axis defined in your head, you then slowly slice away at the hard achene in a direction along/parallel to the long axis of the seed, until you have removed enough achene to identify the cotyledon end of the seed. Now you can slowly extend the attack to remove the entire cotyledon end of the achene.
Soon enough you will end up with the radicle end of the seed buried into what is left of the radicle end of the achene. At this point, a few gentle wiggles on the seed with your box cutter blade usually dislodges the seed out. If it fails to dislodge easily, then a few more careful slices on the achene remnant should do the trick. Damage to the radicle is to be avoided at all costs, so this is the critical and most defining few cuts you will be making…(damage to the radicle spells embryo death).
I then place the seed with its seed coat into a glass of water for a while until it visibly hydrates a bit (it gets firmer and shinier). Sometimes if you are lucky, the seed coat has been sliced a little through the achene removal, and the embryo pops itself out through this slice in the glass of water…(this is very time saving when it happens!!!).
Most of the seeds however have a pretty much undamaged coat if you have been “good at it”, so they require extraction of the seed coat. In such seeds, I then proceed to remove the seed coat by making a very superficial side-ways slice at the cotyledon end of the seed coat, to just reveal the pearly white surface of the embryo underneath.
I then slowly nick away and pull away the seed coat with the box cutter blade, always avoiding getting anywhere near the radicle end. The seed must be handled delicately yet purposefully with the fingers of one hand, whilst using the cutter with the other hand to unfurl/peel away the seed coat layer. Much care is required to not squash the embryo here with the fingers holding it in position. Sometimes the embryo pops out at a critical point of losing most of its seed coat. However, in other cases it does not release itself easily, in which case I do not remove any more seed coat if it is nearing the radicle… Instead, I immerse the semi-extracted embryo into a glass of water until it finally pops itself out.
An advantage to using the box-cutter is that you can slice at short/acute angles which gives you very good control of where you direct the forces, to avoid crushing the embryo underneath. The knife must be very sharp of course, otherwise you will be forcing it too much to make the cuts, and thus risking blunt force injuries to the embryo within."