Effect of drying seeds

I’m in process of testing for one CV (Country Dancer) both short and longer drying, freezing in the hips, holding in frig of the hips, etc.

I’ll be interested in seeing your results, Larry.

I can’t speak to the effect of drying on germination by the usual method of refrigeration and stratification. However, drying does not appear to have a detrimental effect on the viability of rose seeds that are germinated using embryo culture. In fact, refrigerating seeds that have been thoroughly dried seems to be a very effective way to store them. For me, this has been true for seeds from a wide variety of roses, not just species.

In my experience freezing of seeds seems to be a risky thing to do, especially without first shelling them out and drying them completely using a desiccant such as silica gel.

Don and Larry.

Pierre’s Rutten’s very interesting observations in his “septic way sowing” thread (posted late 2009) are what got me to speculate here that dried Clinophylla achene may germinate significantly faster than the fresh equivalent. It is just speculation on my part.

I love the simplicity of Pierre’s method, and I am giving it a try this season (I am still not sure if I will also do the 6 week fridge stratification, or not).

For all the readers here who are interested in the jar method of embryo culture of rose seed, I would now also like to post the results of a little comparison study I did a few weeks back (please refer to discussion above dated Fri, Feb 12, 2010).

To recap, I chose a four-cotyledon embryo and its sister seedling which had the usual two cotyledons to act as a control (both derivatives of ‘Flower Carpet-white’). I wanted to show what for some time I have repeatedly come across, namely that germinations are happening with a high % of success, when they have been cultured in a jar only up until they start to green a little, and well before they grow a rootlet (this is a considerably shorter duration of jar culturing than I used to do last year, when I first experimented with rose seed embryos as opposed to other plant embryos).

Both of these germinated after a few days of burying, as can be seen in the pictures below.

I have definitley changed my position on when I personally will be happy to remove embryos from jar culture and plant them directly by burying them completely (but near the surface) in commercial seed raising mix.

This sort of germination success has happened using modern cultivars, as well as a variety of rose species like Multiflora, Bracteata, Clinophylla, and others.

These conclusions relate to the jar culture method of rose embryo culture, and are not intended to contradict or challenge the wonderful work of others here, who use different methods of culture, and for whom I have absolute respect, by the way. It is all in the name of observing things, that’s all!


Germination at day 4 after burying rootless 4-cotyledon rose embryo with greening cotyledons

Germination at day 4 after burying rootless 2-cotyledon rose embryo with greening cotyledons

Here, the 4-cotyledon embryo at day 7 of germination.

(Note the mould-resistant snail baits…thank goodness for that invention…lol…the mouldy ones nearly made me vomit).

And finally, the 2-cotyledon embryo shown here, also at seven days following its germination.

Here you can see one of my multiflora seedlings, just emerging, this morning. This one was cultured in the jar for something like 4 days, and it greend partially but had not developed a rootlet. It has germinated after only 2 days!

I have noticed that some diploid species embryos are much faster at germinating than things like flower carpet, the slowest of which can take up to one week to germinate after being buried in the same manner, and at the same immature stage of development (ie. partially green/no rootlet).

One incidental advantage to burying them at this early stage of development, is that by definition they dont get any root damage in the transfer from jar to planting medium (which would spell death), as there is no root!

Another huge advantage to there being no rootlet, is that the embryo can basically be plonked into the little hole any wich way it goes in. It will orientate its roots down and germinate with no troubles, sometimes it even has the typical hair-pin bend appearance.

Here is how I transfer them from jar to seed raising mix:

I just pre-wet (flood) the pot containting the seed raising mix until it has settled and formed a nice flat surface after the water has drained. I then swirl the jar containing the embryo(s) on the side of the jar until the water on the bottom of the jar scoops them all up. Then I tip the water plus embryos onto the surface of the seed raising mix. Using a small wooden skewer, or flat knife (or whatever similar is available), I make a tiny hole in the wet seed mix, scrape the embryo into the hole, and then gently water over a little mix to bury it, using droplets of water to make sure the embryo does not sink any lower than a few millimetres.

Because the mix has been pre-wetted, and the mix holds moisture well, I never water the surface, save for a few squirts with my hand held mister in case the weather has been so hot as to dry the surface out (rare, as the embryos germinate many days before this usually happens!).

I keep the pots in a shaded position and sheltered out of the rain and elements.