Embryo culture and R.gigantea

Technique Embryo Culture
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1

R. Gigantea seed which I received from India 10 months ago gave zero germination by embryo culture. That seed was extremely dessicated.

I am wondering if the real cause of this failure was related to the seed embryos having been damaged by the dessication and maybe even the air travel (cold cargo holds).

So, in this thread I am going to repeat embryo culture of R.gigantea seed to see if fresh seed gives any better result than zero germinations.

Today I got 7 fresh R.gigantea achenes, and found that 5 of these achenes contained fresh healthy embryos whilst 2 had gelatinous embryos which were thrown out.

I’ll culture these 5 healthy looking embryos in a glass containing moistened peat moss. The embryos will be placed just under the surface of the peat moss and against the edge of the glass so that their progress can be easily monitored.

I’ll try to post pictures if I can.

These 5 embryos are currently in a glass of tap water soaking overnight, and I plan to culture them in the morning.

2

I just sowed them after an overnight soaking in tap water. One has a bit of its cotyledon sliced off length wise, but not enough to worry me.



One little plastic jar contains 3 embryos, it will be left to culture at room temp (65F-77F).

The other little plastic jar has 2 embryos which I will put in the fridge. The fridge temperature is set to warmer than half way on its dial, which I am guessing makes the temperature roughly 6C (or~43F).

3

ROOM TEMP RUN (3 embryos): 2 dead, the remaining one is greening but not growing.

FRIDGE RUN (2 embryos): both alive, white, and not growing.

This current R.gigantea run used embryos extracted from fresh rose seed (hips were still green but very large, and the achenes were very hard).

It is possible these embryos are very dormant. They were certainly very healthy looking and fresh when extracted last week. Those from India were very dry waxy and brittle/hard (I wonder if those changes were due to the dessication of that seed).

Although it would be silly of me to conclude anything much here in this “study”, what I am seeing here seems to suggest to me that some of these R.gigantea embryos have a substantial embryo dormancy in them, which is a barrier to germination on top of the extreme physical barrier they have in their concrete-hard massive achenes.

4

Glad to see you’re still having fun George. I’m curious about the gigantea seeds - I’d like to get a batch if you know of where they might be had.

5

Hi Don.

Yes it is fun/interesting.

I currently don’t have any more to play with, I have requested more seed in the mail from locals, will let you know if I get lucky with more and I will send you half of whatever number of seed I might get.

6

That’s a gracious offer George but I’m afraid I can’t import them from Australia. It’s one of the verbotten countries, includes Italy and a few others.

7

Ohh…that is too bad!

:0(

Girija and Viru Viraraghavan (India) sent me seed of R.gigantea last year. You could always ask them for some seed, no?

They sure are very wonderful and generous folks when it comes to sharing these types of treasures!

8

[quote=Don]

That’s a gracious offer George but I’m afraid I can’t import them from Australia. It’s one of the verbotten countries, includes Italy and a few others.[/quote]

Mr Holman I presume, Don, does every state in the USA have different import rules for rose seed ? If so how would we Australians find out which states let seed in ?

9

David, the problem is a National one. Some states (California for one) have even stricter rules about many things. It’s particularly those states with larger agricultural economies.

10

Thanks Kim, is there a better state to send to from Austarlia that you know, so they then can be then sent onto another state. How does Canada to USA go ?

11

I hope I have not placed anyone off gaurd on this forum with my wording. I do not know the rules for importation of seed to the USA, even to a state, less state to state. I will make myself aquainted with your government rules on this, If I every have some seed to give away. Regards David.

12

Hi David,

I am replying to your comments above just to help out, I am certainly not meaning to be a pest.

:astonished:)

Our friends from the USA are advising us that sending rose seed from Australia to the USA is forbidden. I certainly never have, and now armed with this information certainly never will be sending rose seed/pollen or anything remotely related to such things to the USA.

Thanks Don and Kim for the clear and very timely advice on this matter!

:astonished:)

13

Unfortunately, we can’t send or receive any plant material in the USA from Australia. It’s an old trade war thing and has nothing to do with the spread of anything. It should be revisited by both countries. It’s doubtful that it will be though.

It’s true that some states have stricter import regulations from state to state and that has a lot to do with trying to stop the spread of invasive insects, plants, and diseases. However, in this “global” economy it hasn’t been all that effective. Goods are being shipped around the world carrying all manner of things from place to place in the packaging alone. Many things have been introduced into the Great Lakes from the bottoms and bilge of the cargo freighters themselves, not even the goods they carry. And I’m sure air freight planes bring things in too. It’s a huge problem with no foreseeable solution because there’s too much money to be gained by the sales or lost by bans or enforced cleaning regulations.

14

I got tired of monitoring+/-watering the exposed damp peat moss in the fridge in this container every few days, so I added plastic wrap and elastic bands to the top of the container as an easy means to maintain moisture.

No other modifications.

15

Hi Don,

this group are selling seed labelled as coming from some R. gigantea (click on link below, and add the word “rosa” to the box that says botanical name…doing that should then bring you to their listed rose species…Hmmmm I see R. laevigata seed!!!..hmmm … o_O…too bad there is no R.persica seed, oh well maybe they’ll have that one some other day perhaps…).

I might even give them a go as well if I don’t get lucky locally this time round again with my search for more R.gigantea seed. Yes, I can be greedy about such things.

:O)

http://b-and-t-world-seeds.com/letters.htm

16

ROOM TEMP RUN (3 embryos): the third one is also dead, it was greenish/transluscent with small dots of mold starting to appear at various points around it. I am not surprised.

I am going to examine the two which are sitting in the fridge tomorrow morning. If both are still alive I am going to take them out of the fridge and challenge them for 24-48hrs with room temperature. If any start to sprout a radicle fast, I’ll remove them and sow into germination mix. Any which do not sprout a radicle will be placed back in the fridge, and at weekly intervals subjected to the same room temperature challenge for 24-48hrs, to see what happens.

17

Both embryos are ok.

Both were removed and placed in a glass of tap water for a few minutes whilst I squeezed out excessive moisture in the peat moss (I felt it was likely too wet…after squeezing out the excess water the damp peat moss would now fall out of its container if that container were inverted and shaken).

Both the embryos were placed back into the container with the now damp peat moss, both facing against the side of the jar so they can be seen easily, and near the top of the peat moss, and then covered lightly with a few bits of the damp peat moss. Then the container was sealed off with plastic wrap and elastic banding.

The container is now at room temperature for the 1-2 day trial.

18

Guess what!!!

Both refrigerated embryos are dead.

big yawn

From observing such R.gigantea embryo (EC) trials over the past year, it makes me guess that a fairly high percentage of the fresh (unstratified) embryos as well as the waxy (=? very dry) type of embryos might be deeply dormant for this species. I suppose this is stating the obvious, or is it?

19

You know, R.gigantea achene germination reminds me a lot of my work with germinating olive seed/pits.

The olive pits are as hard as cement, similar to gigantea. The olive pits take 1-2 years to germinate naturally, (I have read somewhere that R.gignatea can take as long as that to germinate also).

I tried germinating olive embryos by direct sowing in seedling mix, without any period of stratification and found that a percentage of them germinated within a couple of weeks, whilst many of them died (I presume they were the more embryo-dormant in the population).

I got hugely improved germinations however the following olive harvest, when I decided to remove the hard olive pits, but not extract the olive embryos from their fleshy seed coat. Instead that year I sowed the intact olive seeds (minus the hard pit of course) and found after about 4 weeks that when I took those seeds out of their germination media and extracted the embryos, those embryos then went on to germinate very rapidly and with nearly 100% germination. A huge improvement!

This makes me wonder that the olive seed coat imparts some essential benefits which are vital for very dormant embryos to have, in order for them to mature and lose their embryo dormancy and to then go on to germinate fast. It sort of makes sense, of course there is a reason why things have been put there in nature, no?

Could the same be said of the rose seed coat in the case of R. gigantea (and indeed other rose seed)?? Could the seed coat for those rose embryos which happen to be quite dormant be a very essential/nourishing thing for them to retain, in order for them to mature out of their dormancy? Goodness knows how awfully fragile those very dormant rose embryos become as soon as they lose all of their coverings!!

I have never really seriously trialed rose seed (hard achene coat removed but thinner seed coat left intact) in germination trials, yet!

Might it be worth while then to do a germination trial for R. gigantea where those thick dense rock-hard achenes are totally removed, but the resulting R.gigantea seed coat is retained and we do a rose seed germination attempt rather than a rose embryo one?

This is what I intend to do next!

I am currently waiting on some OP seed from a R.gigantea from France, in order to do this study.

I aim to post information on this attempt here, as soon as this gets underway.

20

Yes George, some seeds do in fact require what is called after-ripening. While trying to write up my germination tests, I came across a couple very interesting papers on this topic. Someone once looked at embryoes of 11,000 species and categorized them in to differnt shapes, ways of folding up, maturity at fruit fall and so forth. Unfortunately the main paper I read, by Betty Atwater, was focused on annual garden flower seeds and didn’t address roses. Someone else quoted it in relation to roses, but without evidence that they really do require this kind of ripening. But for R canina as mentioned on another thread, there’s sure something going on.