tracking seed germination

Post a reply

BBCode is ON
[img] is ON
[flash] is OFF
[url] is ON
Smilies are OFF

Topic review

If you wish to attach one or more files enter the details below.

Expand view Topic review: tracking seed germination

Re: tracking seed germination

by jbergeson » Sun Jan 19, 2020 7:33 am

Not adding much here:

I remember two batches of R. foliolosa seed, pollinated by different parents, seeded in the same tray on the same day, germinating distinctly a few days apart. This would seem to indicate an influence of the male parent. However, the extra variable is hip ripening time. I didn't keep track of when I made the cross, and one of the two batches could have been from hips pollinated a week or two earlier than the other.

(I remember posting about it at the time, so more details should be here somewhere if you search.)

Re: tracking seed germination

by Larry Davis » Sat Jan 18, 2020 11:23 pm

Sorry, had to go for supper before finishing that one. Rushed a bit too. What happened with R. canina seems to be that there is a critical stage of ripeness when they germinated fairly fact and very well. Too early, or too late and they are much harder to get to sprout. I the UK this was studied decades ago. Their conclusion was that red ripe but not soft was optimum. I would agree. I've no idea how this applies with other species, or complex hybrids. I have found that in many cases, a warm spell after a long cold vernalization/stratification in refrigerator, will allow germination i the next winter. Sometimes a whole lot. And those picked too early or too late for easy first year germination often pop up a lot.

My conclusion, it's really complicated. Probably I should take all the failed achenes at the end of 2 years and see if there is still an intact embryo inside. Don H has found that in some lines, maybe many, there may be a rather high % of non-viable seeds. But if they are viable, how can we get them out of dormancy? No good ideas.

Re: tracking seed germination

by Larry Davis » Sat Jan 18, 2020 7:20 pm

AS I recall, the original observations by Risley were for looking at just one parent, pollinated with a range of donors. He was interested in noting that whatever regulates germination, the pollen donor introduces something (presumably genes but possibly methylation patterns) that affect the production, degradation or sensitivity to hormone. When he was writing, it wasn't yet clear that abscisic acid (ABA) from tha testa was a likely determinant of germination. But even now we don't know how sensitivity to ABA is modulated, or genetically determined.

Vernalization in plants that act as biennial (such as some strains of the weed arabidopsis, depends on modifying the methylation status of a specific gene which then in turn affects expression of a bunch of genes. So it is likely that something similar happens to break dormancy in rose seeds. I observed that nitrate hastens the process somehow, but doesn't seem to affect the total germination in the long haul. In one rose species, an ingredient of smoke also has this effect, as it does in arabidopsis. So there must be multiple pathways controlling.

I have noticed that when the pollen donor is something that ripens very fast, the hips formed on receptor plants may ripen faster than when the pollen donor is slow maturing its own OP hips. For instance R pomifera normally ripens seeds from May 1 flowers by July 1. Above and Beyond tends to make hips ripen faster than some other pollen donors on the same female. But germination times are not tightly related to this if my casual observations are correct. I will make a more careful count of last year's results and post it.

What I do notices, for sure, is that some combinations have very synchronous germination, while others spread over several months. I also notice that the exact time of harvest can really have big effect in some strains or species. For sinstance R. canina really vary a huge amount over a couple months of harvest time, in the same year.

tracking seed germination

by mntlover » Sat Jan 18, 2020 6:21 pm

What kind of information do you keep track of in your records?
What details about germination do you keep track of?

I just realized (and, yes, I'm a little slow in this) that if the male is responsible for length till germination (as someone was kind enough to share on here recently) Karl?, then perhaps my germinations are not as spotty as I was thinking. It seems that I'll get a few or a burst (depending on number of seeds from a certain pollen parent) then I will have a lull for a bit and then another spurt of seeds germinating.

I just realized that I should have expected this since I have tested anywhere from a couple to a handful of pollen donors on a bush, mainly because I am testing the seed parent to see what it does. I didn't (due to moving) keep the seeds from the different pollen parents separate, just the seed parents. This would explain why I have bursts in distinct time periods of germinating seeds. Has anyone else noticed this? And, yes, in the future I plan to keep separate the seeds from different pollen parents.
Do you think this is an accurate assumption?
What are some other details you have noticed in recording your germinations?
Also, any high percentage germinators you would recommend?

Thanks for any thoughts!