JAR EMBRYO CULTURE.....NUANCES AND NEW DISCOVERIES.

Recently I have discovered that if you remove the rose achenes from the hip, then saok them for a couple of days to remove all impurities and bits of hip, then air dry them for several weeks until the achenes are stony hard, then it is much easier to do the achene extractions. Extractions done on freshly collected achenes from a hip versus extraction done a few weeks later on the remaining stone dried achenes from the same hip have proven infinitely much more difficult for me, by comparison.

Part of this ease is to do with the easier handling of a dry seed in your hands (better purchase, less slipping), but also the blade of the box cutter cuts with greater efficiency and less need to recut/force the blade, as the dehydrated achene offers less elastic recoil force to the action of the blade. A bit like how it is easier to slice through a banana than a sponge (ok this is an exaggeration, but you get the point?!!). This means less pushing action when cutting, less re-slicing, and so less potential damage to the seed underneath…and so it is also much FASTER.

Only extra sharp previously unused box cutter blades are to be used for best cutting, there is risk of injury, I cannot accept responsibility for this…be careful or just don’t attempt this if you are clumsy! Also it is best to keep others well away from your operating field, and wear protective eyeware, as occasionally even in the best of hands, seed flies in your face or around the place…(this happens less as you gain experience…LOL).

Another fantastic advantage to drying is that the seed within the achene has also dehydrated and shrunk in volume…but since the achene volume has not shrunk anywhere near the same amount, an air pocket develops around the seed…the drier the seed the more it’s potential volume is replaced by air…This is an insurance policy because the box cutter blade sometimes slices into an air pocket where otherwise it would have struck seed if the seed were fully hydrated. So there is more room to negotiate the slicing without injuring the seed…very cool :0)

Dry achenes with this air pocket within them have also led me to propose something else in relation to why some viable achenes float…

Some achenes have dryer seed than others, for whatever physical reason (eg. extra leaky sutures, or more leaky achene shell)…the drying shrinking seed within such achenes has air replacing its volume as it shrinks. The more dehydrated and shrunk the seed becomes inside the achene, the more volume of air exists to replace the seed volume. At some point of this seed dehydration phenomenon, the buoyancy forces of the water around the achene become greater than the sinking forces as the achene becomes less and less dense…and flotation results.

So NEVER throw out achenes that float!!! They float because there is air in them…some are just achenes with dry viable seed and air pockets, while others are 100% air filled (contain no seed).

Oh, and by the way, if placed in a glass of water the very dehydrated seeds/embryos spring to life very very fast. Nature has it all worked out!

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One last refinement… just before closing the lid, exhale a few times into the jar so the glass fogs up all the way around and to the top, this way humidity is delivered immediately right up close and personal to the babies.

I find that smaller baby food type jars are the best, as they provide a superior seal thanks to their lid design. Also, the smaller the jar the more successful it is to maintain high humidity without much fussing about after the lid is closed.

Here is a picture of the final set up.

You can see just see a few (‘R.Clinophylla’ x OP) embryos happily clinging to the side of the jar, well away from the water line… (Simon, of course these are the ‘R.Clinophylla’ you sent me via Viru in India…very cool…they just got put in this morning as most of them seemed only moderately viable, and so I had them swimming in water for 48hrs to try and rehydrate them maximally…some have started to open their cotyledons and thicken up from this pre-treatment, so there should be at least a few germinations…these were very tricky to extract as their achenes were very dense and the embryo inside was very thin and spindly, and when first extracted most were a dull off-white rather than the derised shiny pearly white).

BTW the jar size shown above easily accommodated all the 14 of these babies.

Simon, as you know, I got six ‘R.Clinophylla x R.Bracteata x OP’ species cross embryos from your Viru supply.

In contrast to the ‘R.Clinophylla x OP’ embryos, these showed excellent viability right from the start.

Here is one of them after 24hrs in culture.

Do I detect a little “greening” going on?!!

The small baby food jar shown 3 postings above is very close to actual size, the real size being maybe 10% larger than what shows in this picture (I am assuming your computer screen is set to ‘100%’ magnification).

(R.Clinophylla x OP) 24hrs jar culture…definitely some of these poor quality embryos did respond to the extended pre-culture rehydration regime (immersed in tap water for 48hrs).

Here is the fastest of them:

(R.Clinophylla x R.Bracteata) x OP, 48 hrs jar culture.

All six of these are just powering on, as predicted. I can only imagine what monsters thay are going to grow into.

They get big. I had them here but gave them all away.

It’s interesting to see the variety of seedling types. They tend to favor one parent or the other to some degree.

It’s fascinating to see their development via embryo culture.

Btw, this seed germinates quite easily.

This particular batch of ([R.Clinophylla x R.Bracteata)] x OP achenes should germinate very easily if planted directly as achenes judging by the ease of extraction (thin seed coat) and the vigour of the embryos.

On the other hand, I have a feeling the other species (R. Clinophylla)xOP achenes will probably be a tad less easy to germinate when planted out as achenes in germinating medium, but their embryos are marginally alive as the culture proves here…as I explained further up, their seed coat was very dense, nothing like the thin coat of the ([R. Clinophylla x R. Bracteata)]xOP achenes.

Having said that, I can’t see there being any shortage of seedlings, even just from this lot that I have. I have no idea what I am going to do with them all!

Robert, which particular species from Viru are you referring to, when you say you gave them all away?

I’ve germinated both clinophylla OP, and clinophylla x bracteata seed here.

It all germinates easily and I gave them all away.

I’m not saying they weren’t worth working with, I just had too many other things going on. I chose to work with Viru’s derivatives instead since I had access to them.

As I’ve stated before, not to utilize the work of others seems in a way a discredit to their effort. At least that’s how I looked at it in this particular case.

We can only spread ourselves and our resources so thin anyway.

Robert, did you get to test either/both of these species seedlings for seed setting fertility?

I tried working with clinophylla. It got huge. My specimen was about 12’ tall after two seasons. The few attempts I made to work with it were not successful.

I discovered Powdery Mildew on some portions of the plant that were not getting good air circulation. That’s when I decided not to work with it directly. I gave my vigorous clone to the San Jose Heritage Rose Garden. That’s where Cass got her specimen.

Paul Barden’s specimens were germinated independently.

Btw, a few of them were dwarfs. I think I gave one of the dwarfs to Kim Rupert.

Robert… these clinophylla x bracteata OP seeds are Viru’s work… based on his initialy clinophylla x bracteata cross selections. As an aside here, these OP clinophylla x bracteata seeds come from a plant that Viru has selected as the most tolerant of humid conditions… the parent plant is growing next to a pond and experiences periodic flooding… Now that we know we can get seed from other countries here without too much trouble maybe we can obtain more advanced seed material as well from all over the world, as I have now successfully brought seeds in form India and the U.S.

Oh, and the clinophylla x bracteata seedlings of which there were about 20, were all donated to the Ventura Cty. Rose Society Auction one year.

One of the volunteers had custody of them. That’s the last I saw or heard anything about them. They seem to have vanished.

If there are dwarfs in any of these, I am going to use those preferentially, with the hope that the dwarfing may pass onto a percentage of any F1 that result.

Simon, yes, I know. We all got the same seed.

You will note there are quite a few descendants. I decided to work with Viru’s more advanced derivatives.

Paul Barden has done the cross [(0-47-19 x self) x R. Clinophylla]

See HMF links below for some of the resulting seedlings.

I wonder, is R. Clinophylla a difficult seed parent, and better used as a pollen parent, as Paul has done here?

My attempts to use clinophylla as seed parent were not successful. I’d bet it’s possible, but I decided not to pursue it any longer.

I have one of Paul’s hybrids here. I have my fingers crossed that it will flower for me. Last year I got one blossom. I used it on ‘Riverbanks’ which is normally quite fertile with pollen of any ploidy. One hip aborted and the other was small with a couple of small seed. I have them sown but no luck as yet.

It would be nice to get a remontant diploid clino. line etablished.

Sure would Robert. Lets hope you are successful this time round… crosses fingers