Some seed questions.

General Discussion
1

Hi Everyone!

I’ve germinated a fair number of rose seeds, but I’m by no means an expert. So I have some questions that I’ve always wondered about for the experts out there:

  1. Are floaters always non-viable?
  2. Is there a definitive correlation between seed size and viability, and/or eventual seedling survivability?
  3. Can seeds die if left on the plant over the winter in a cold climate (Zone 4 here)?

Thanks!

Tony

2
  1. No. Rugosa seeds, for instance, seem to always float due to surface tension. See also my suggestion in #2.
  2. There are certain roses that just have small seeds, and they can be perfectly viable. However, I think you’re asking about seeds of different size from the same hip. I’d recommend taking a fingernail clipper to a few dispensable seeds to see what the embryo/testa/whatever looks like inside - you can draw your own conclusions about viability related to relative seed size. I’ve been doing this and it is kind of fun. Plus a couple of the embryos that I’ve cut out and shoved in some germination mix have actually sprouted.
  3. I don’t know. Again, you can probably tell by cutting some open and looking at the embryo.
3

Thanks for your help! I’m going to ask some follow-up questions for each original question:

  1. In non-Rugosa seeds, is there a correlation between floating and being non-viable?
  2. I’m going to rephrase my question to read “Is there a definitive correlation between relative seed size within a given hip and viability, and/or eventual seedling survivability?” I’m noticing huge seeds in some of the hips I’ve been processing, but then also many tiny seeds. I’m wondering if anyone has drawn a correlation so I don’t waste my time cleaning and treating all those tiny seeds if they’re likely to be non-viable.
  3. I haven’t done any dissection of seeds to look at the embryos before. What should I look for as far as how a viable embryo would look compared to a non-viable one?

Thanks again for your help! I appreciate it!

Tony

4

Don Holeman would be the best person to answer these questions.

When I attack a seed with the clippers, I figure if it looks white and somewhat plump inside it’s probably still good. Usually I screw up and squish out some white stuff. If the embryo is dead, missing, or non-viable it would likely be brown inside or absent. Don’t be afraid to just try it with seeds that are fully expendable - just start clipping away with a fingernail clipper until you get to the middle. There is a brown skin over the embryo, but if you squish it it should be white inside.

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Thanks!

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I’m hoping Don Holeman will see this and give some advice. I can’t find him on the list of members. Not sure what his username is.

7

Hi Tony. I’m a beginner here. Don Holeman’s guide to embryo extraction, plus videos by others of the process at: Embryo Extraction from Spinosissima(?) Scotch Rose Seed - Rose Hybridizers Association Forum

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Are floaters always non-viable?

Peter Harris once sent me a batch of floaters to test this question, I extracted embryos from a couple hundred of them. The first 199 had no embryos. The very last one had a fine embryo.

Is there a definitive correlation between seed size and viability, and/or eventual seedling survivability?

This is basically the same situation as floaters. In a batch from a single cross having a bimodal distribution of large seeds and very tiny seeds the tiny ones probably do not have embryos but you just cannot be certain. I decide which to keep and which to toss depending on how important the cross is to me.

Can seeds die if left on the plant over the winter in a cold climate (Zone 4 here)?

It depends on how well dessicated they are before they freeze. I just recovered three hips off of Bill Reid that I had missed in the fall and queued them up for extraction, and I do the same pretty much every season. Keep in mind that the international seed repository is located in the arctic. In fact, I once extracted embryos from omeiensis seeds obtained from the USDA that had been in the deep freeze for 25 years. Two embryos out of (iirc) 19 seeds germinated and I still have both plants (last I checked).

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Thanks, Don!

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Yes, thanks very much Don! And thanks to jbergeson and Roselyn too!