Rose embryo culture for backyarders....still searching

General Discussion
1

I still think rose embryo culture (EC) for backyarders can be improved. One recent personal “rose embryo success story” has spurred me on to not abandon embryo work altogether which I have nearly done (I hardly ever embryo culture since the last 6 months or more).

Out of desparation to get some germinations happening, in the last month or so, I decided to EC one batch of OP seed that did not germinate by stratification and sowing. Embryo extraction (EE) of that seed showed most seed to be rotted, and I suspect the seed parent is a poor germinator. EC of four embryos which were retrieved from that seed resulted in three deaths, and one seedling which is thriving now about one month old. This was all done in late spring/summer conditions!

Of course, no-one can say if those four seeds would have ever germinated naturally, if left sown in the original media throughout the remainder of our summer or beyond.

This time round, EC got me a head start, to be sure, one seedling now is better than none in my books.

Over the last several years, I have tried several of my own experimental methods for EC (Jar embryo culture, WEC, driect sowing into commercial seedling mix), as well as others’ published methods very recently.

I have one batch of seed that gave 0% germination (N=8 embryos) by following one published EC method very closely.

I am still searching for improvements in EC.

In the next few days, I am going to try a different method.

I have always liked the idea of sowing the embryo from the start, but I was never able to think up a media to do this in an easy practical way. I tried perlite last year, and that gave bad results.

A few days back I thought why not use jars (small plastic and/or glass baby food type jars) and sow the embryos radicle down into damp peat moss in the bottom of those jars, so that you can just see their cotyledon tips popping above the surface of the peat. Each jar will be sealed off with see-through plastic wrap and elastic band, and I will do nothing else but watch them.

I will try this proposed way of EC (i.e. jar + damp peat moss) on the same batch of seed that gave zero results mentioned above, to see if the results are any different (this time N=5 embryos, and I will omit peroxide).

NOTE… We are in our summer here, the weather forecast from last week to end of this week is much the same conditions, so the EC comparison is “temperature similar” from the first run comparing to this second run, as far as I can tell. The temperatures have been unusually very cool for us so far this summer.

I will post results, here.

2

I now also have another different type of OP seed (N=7 embryos) which also gave 0% germination using some published method.

:astonished:(

I have today also resubmitted 6 embryos of that particular seed to the peat moss+jar idea as well.

I have omitted peroxide and fluro lights in these runs. Just using ambient light indoors.

I guess I’ll have results in a couple of weeks time, for these two runs.

3

…or much quicker results if they all die…again!

o_O

4

PROGRESS REPORT:

RUN 1: (N=5 embryos from a batch of seed where EC failed using some other published method):

Some of the embryos started to die.

This run was terminated early, and repeated with “RUN 1a”.

RUN 1a: (N=5 embryos from a batch of seed where EC failed using some other published method):

I re-extracted N=5 embryos from that same batch of seed, and this time placed the embryos on the sides of the jars, and then completely covered them with moist peat very close to the surface. I can see the embryos by looking at the jar side on. There is only a little bit of peat covering each of them. If these start to sprout above the surface of the peat I will remove the plastic cover immediately, and keep the peat moistened as required which should only require a few drops of water every day or longer.

RUN 2: (N=6 embryos from a batch of seed where EC failed using some other published method):

Some starting to green slightly, none dead yet. If they pop up and look “germinated”, I will immediately remove the plastic cover and wet the peat as required to avoid it drying out too much (e.g maybe once daily with a few drops of tap water to keep the surface moist). Note these remain sown on the surface of the moist peat with just the tip of their cotyledons deliberately exposed to the light/air inside the jar.

5

OK some sort of pattern is emerging.

In run 2, the same thing is starting to show up as did in run 1. By this I mean that for some of these 6 embryos, the parts above the peat moss (tips of cotyledons) are molding, whereas the parts that are buried in the peat moss (radicle) are growing and very alive. In other words some of these embryos are alive but are dying off where they are exposed to the surface of the moist peat moss which is also under plastic cover.

So because of this I have now also stopped run 2. I will repeat run 2 by re-extracting N=6 embryos of the same seed batch but this time sow these 6 embryos around the sides of the jars so they can be seen from the sides, and with only a small amount of peat moss completely covering them. I will also omit the plastic wrap altogether right from the start and just add a few drops of tap water if the surface of the peat moss is drying out. I will call this “run 2b”.

As a result of these observations, I have now removed the plastic wrap from run 1a, and renamed it “run 1b”. The 5 embryos of run 1b all look fine so far, and appear to be swelling a bit…they are still superficially buried in the peat moss and can be seen very easily from the side of the jar.

One great thing about this peat idea is that I can now even turn the jars upside down with moistened peat + embryos in place, and no cover, and nothing ever falls out, even when I try and shake it all out!

Yes I am like a kid messing with early X-Mas toys sent from some “rose Santa”.

:stuck_out_tongue:

Grand!

6

Lol, I love your enthusiasm, George! I wonder why the mold developed so late in the game for run 2? Too much moisture or maybe just opportunistic spores in the peat? I have to admit I can’t picture how you can turn the jars over without the peat and plant falling out!

7

Hi Seil,

The mold developed about the same time in both runs, it is just that run 1 was started slightly ahead in time compared to run 2.

As for the peat not falling out of the jars…I can totally understand your disbelief, but it is true to be sure!

It is moistened peat and it has been pushed/packed into the jars, and it then seems to stick as one in the jar. It doesn’t fall out when inverted, even when I shake it (so long as it has been well moistened and packed together as one thing, and there are no loose dry bits of peat in it). I think the other reason the packed wetted peat does not fall out is that these jars have a small opening (diameter just short of say 2 inches).

I sowed the embryos as the last step with a toothpick after first packing all the moistened peat into the jars. I made small openings on the sides where the peat meets the side of the jar, and slipped the embryo into that slit, then covered it lightly with the moist peat.

Usually I add pix to these types of experiments/demos, but alas I cannot ATM, someone broke my webcam and doesn’t care to replace it for me!

Guess I might have to go buy myself a cam for X-Mas.

:O)

8

Seil,

Your question about why the mold has occurred is a very great question!!!

I have seen this type of white mold in all the embryo methods I have tried (published methods, and unpublished experimental methods like water immersion where I have seen white mold covering embryos submerged in water, WEC, jar culture etc…). Some embryos get the white molding more that others. Some embryos never get it, even in the same run/batch where some other embryos have already developed some white mold.

My guess is that this type of mold shows up only on parts of the embryos that have actually already died. There could be molding on one cotyledon, or part of one cotyledon or the whole embryo can be covered in white mold. I cannot prove this casue/effect, it is just my guess. My guess is that the white mold is not the cause of the dead part it is the result of the dead part being consumed by the mold to a visible extent. Some others seem to be of this opinion also, this is not any original idea of mine, anyways that doesn’t matter.

In the original run1 and run2, since only the parts of the embryos that were deliberately left in the air died this way but the same embryos had living parts in their buried portions, it made me wonder that the moist peat seemed ok for them where they were buried. It also made me worry that the surface of the peat under plastic wrap seemed to be bad for them.

That is why I have re-run the two trials as 1b and 2b, where the embryos have been buried totally in the peat moss, and there is no plastic wrap covering used.

We shall see, it is fun to do.

9

I use petri dishes for my seeds with just a little seed germinating soil. That way it’s easy to see when they germinate. I would think that would work with EC, no?

I just found the article on EC in the RHA articles library and tried a few with the very large seeds that refuse to germinate. Of the three, two embryos were dead, one looked very healthy. I’ll try the petri dishes and let you know how it works.

10

Thanks, George! So it isn’t something else causing the embryo to mold but the dead embryonic tissue itself that is molding. Makes perfect sense. Dead tissue would mold as it decomposed. Since this occurred in the ones above the peat most often I would think that the exposure to the air is what caused the tissue death. Maybe too dry because it wasn’t in contact with the damp peat like the parts beneath were? I have found that when I transfer my germinated seeds from the paper towels into the starter trays that if I leave any part of them above the soil they do tend to die off before sprouting as well. So I now make sure the entire root end AND the seed head are beneath the starter soil. I thought I was helping them along by not making them push their way up through any soil but it didn’t help at all.

11

Hi Judith,

let us know what you did and how it went, good luck!

12

Hi Seil,

I am really not sure why their tips which were exposed to the surface of the dampened peat (sealed off with plastic wrap) got the white molding whereas their buried portions did not.

I think it has partly to do with the moistened peat moss surface being sealed off under plastic, and not ventilated. That is why I added ventilation in the latest modification to this trial (by not using plastic wrap). I also modified by burying them entirely. It could be that there is something beneficial in the moist peat moss other than the fact it is moist and holds everything nicely packed in the jar!

What I am saying is, I am hoping that the moistened peat moss also adds the benefit of preventing overgrowth of nasty bugs, and promotes growth of the beneficial bugs as far as the embryos go, so the balance goes towards growth rather than death when the embryo is totally enclosed within the moist peat moss. That is the main reason I chose moistened peat moss as the growth media in this trial right from the start…I wondered if it had special pH chemical and microbial qualities that optimised embryo growth. It is a hypothesis, I cannot provide any proof, I can only trial and report results, and try to understand what is going on according to the trials and their results.

Having said that, these are not original ideas about peat moss and rose seed/achenes in stratification, others have suggested similar things about its qualities in the past. However I cannot recall trials done with it and embryo culture, to my knowledge.

I know for a fact that these two batches of seed I have contain embryos that are alive, but are very fastidious types, they die real easily. These “more tricky to germinate” embryos are the ones that can be most useful when we are trying to push the boundaries in EC. We may learn from them.

All I can do is try and report back.

Anyways, today they are all alive last time I peered at them through the sides of these little jars.

13

I also need to say that a group of “vigorous-type” embryos (which the above ar clearly not) are able to germinate and thrive once sown directly into ordinary seedling mix with no peroxide, fungicide, or any other antimocrobial application. This has happened too many times for me to just pass it off. It is this observation that keeps me wondering whether embryos need the correct balance of microbes to thrive and germinate instead of more sterile growth environments. Dunno!!!

14

Since I germinate all of my seeds in either paper towels, or on top of, or embedded slightly in soil, I can tell you yes, mold will grow more when exposed than when embedded in the soil (which is mostly peat). I feel the peat is an inhibitor (pH?) to the mold growth.

Some molds seem to encourage germination, but in my experience there is a white fluffy mold that almost always is associated with seed death. Whether that mold is growing on an already dead seed or it causes seed death I can’t say.

I’ve done a lot of playing around with mold inhibitors - soaking the seeds in lysol (diluted) for 15 minutes or so, and then washed off, doesn’t seem to hurt germination, but definitely inhibits fungi. Unfortunately, it’s not very effective with the white fuzzy stuff.

Oxyclean (about 1/4 teaspoon in an ounce of water) seems to be good as well and may be more effective against that nasty white fuzz. I will report back on my current experiments soon.

H2O2 seems not to be vey effective…

15

As a novice to this, can I put this forward. Could it be the impurrities that are at the surface of the peat and air.

16

Hi David,

I am no “successful expert” at embryo culture, either LOL. :astonished:)

I am happy with my embryo extracting, but consistent success with EC alludes me, hence this thread!

I really think it may have something to do with the ventilation being poor when the plastic cover is applied, contributing to overgrowth of whatever is microbially “bad” on the surface.

I am hoping that by not ever using these plastic covers, and increasing ventilation that way, this may correct the “problem” to do with molding at the moist peat/air interface.

We can only try and see what happens.

17

Hi Judith,

That will be interesting to hear about, thanks for explaining what you are doing!

I am thinking here in this thread in a slightly different way…

That is, I am trying to encourage the different microbes to play out their game by selecting a media which allows that to happen and encourages the “beneficial microbes” to “win out” if you like over the “deleterious ones”… In that context, in these trials, I am deliberately not using any antimicrobials, because there is a risk that killing some of them with chemicals might mean also killing too many of the good ones as well.

This is the crux of the hypothesis in the trials I am carrying out in this particular thread.

BTW, this is not meant to be any criticism of others’ good work in the field. We are left with no option but to try alternative methods when the best available ways just don’t do the trick.

18

UPDATE:

1b: Some embryos are showing mold (=death).

2b: One has germinated above the peat line, no molding in the remaining ones yet.

19

I have to say that some of these embryos have a bad look about them from the minute they are extracted. Some are waxy/almost yellowish-white, and many embryos are almost mushy rather than nice and firm. Most of the achenes contain outright rotted seed.

It is no mystery to me therefore that none of the #1 embryos have managed to germinate in any of the cultures so far, including published methods.

Our summer continues to be cool and wet here…so much for “Australian conditions” being thought of as" hot and dry".

o_O

The temps have hovered around 65-85F during these trials.

I just started another run with one further modification with embryos from #1 seed batch as these have proven to be the worst performers (it will be the last run of this thread).

RUN 1F: These embryos (N=5 again) were placed in a drinking glass with moistened peat moss just like in the “b” runs (i.e. the embryos were positioned on the sides of the glass and buried a little below the peat moss surface, so their progress can be monitored easily by looking at them from the sides of the glass). The modification in this run 1F is that the glass container was placed in a fridge, set to a fraction warmetr than the “medium” cold setting (I guess about 6 celsius).

20

UPDATE:

run 1b: all dead, molded (mainly white mold, some blue mold as well).

run 1F: all alive (no molds, no growth evident either).

run2b: One definite germination, hard to tell what the rest are actually doing at this point in time, some look alive.