Old seeds...

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philip_la
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Old seeds...

Post: # 66640Post philip_la
Tue Dec 12, 2017 12:05 am

Apologies -- I know this has been addressed time and time again, but cannot find info...

I have seeds that are 2 years old, having remained in the hips (now completely desiccated, or course) and in the fridge for *most* of this time with only a paper envelope for protection... These include well over a dozen crosses involving plants I no longer possess in my collection, and some are IMO very interesting/difficult crosses, so they have value to me.

From earlier posts, I know there is a remote chance of viability. What would be the best/safest technique for germinating them successfully and within a reasonable time frame?
1. Best means of reconstituting dried seeds/hips?
2. safest means of extracting from the leathery hips?
3. Best technique for germination?
4. Anticipated time for germination (modern hybrids) and guidelines as to when to throw in the towel?

Thanks!
Philip F.
[size=small][color=#669966]Zone 8 / Sunset Zn 30 (Austin, TX -- formerly New Orleans, LA)[/color][/size]

Don
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Re: Old seeds...

Post: # 66644Post Don
Tue Dec 12, 2017 3:20 am

A lot depends on the condition they were in when harvested and dried. Assuming the best then your favorite germination protocol will work as well as anything else. Make sure to imbibe them well with cold, cold water to revivify them.

I have found reduced viability with embryos extracted from aging seeds but not catastrophic by any means. I have mentioned before I have two plants of omiensis from seeds that were twenty-five years old.
What doesn't kill them makes them stronger.

Karl K
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Re: Old seeds...

Post: # 66654Post Karl K
Thu Dec 14, 2017 9:50 am

This is from The Rural New-Yorker, 66: 304 (Apr 6, 1907)
Old dried [rose] seeds are very unsatisfactory, but if valuable, may be to some extent revived by packing in layers of moist sand in a perforated box—or in other words, stratifying them—and burying the box in well-drained soil 20 inches or more deep for a year before planting. This depth is so great that sprouting is not likely to occur, but the living kernels remain dormant while the hard, bony shells soften and decay. We have had a fair proportion of old rose seeds thus treated come up within two weeks after planting.
http://bulbnrose.x10.mx/Roses/breeding/ ... e1907.html

Reychler (1938) took a more direct approach, that does involve more effort:
In September 1937 I threw some peach kernels (amygdalus) into a box. This box, put away in a corner of the kitchen, drew my attention in June 1938. On June 6th I broke 10 kernels with a hammer, took the flat, dried and hard seeds out and placed them in the hothouse at 20-25 degrees (C) on very wet sphagnum. After two days, on June 8th, the seeds, saturated of moisture, looked like fresh ones. Of 8 seeds I uncovered the germ by operation, removing the membrane that covers them. Two were left undisturbed, as witnesses. After 24 hours I noticed the change in all the individuals that had been operated on; 48 hours later germination was obvious (1). The photo opposite was taken on June 16th. It shows how far germination has progressed with the eight individuals that were operated on, whilst the witnesses did not show any change.

This experiment gives ground to the opinion I so often expressed: that with many seeds, those of orchids included, the difficulty of germination resides in the weakness of the germ that must pierce the enveloping membrane.
http://bulbnrose.x10.mx/Heredity/Reychler/reycseed.htm

Rick and Bowman (1961) described methods for improving germination of Galapagos tomato seeds that seem to support Reycher's opinion.
Seedlings have been observed literally to pop out of the seed coats within minutes after these repeated treatments as if they had been simply unable to break through the seed coats.
http://bulbnrose.x10.mx/Heredity/RickTo ... d1961.html

The embryos of old seeds are weakened, reducing their ability to push through membranes and shells.

philip_la
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Re: Old seeds...

Post: # 66675Post philip_la
Mon Dec 18, 2017 12:39 am

Thank you both for your insights. I have never had any success with old, dried seeds in the past. Don, thanks for the water temperature info -- I probably would have tried with tepid water. I've also never attempted any embryo extraction, but might do a little practice run on the White Out hips I collected, also now dried out. <sigh> This parenthood thing seems to keep me a tad distracted...
Philip F.
[size=small][color=#669966]Zone 8 / Sunset Zn 30 (Austin, TX -- formerly New Orleans, LA)[/color][/size]

Don
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Re: Old seeds...

Post: # 66678Post Don
Mon Dec 18, 2017 3:05 am

>> I probably would have tried with tepid water.

The solubility of oxygen in water is inverse to the temperature. I once had a baggie full of seeds germinate in the middle of winter in the refrigerator almost at the freezing point because they had been sitting under the drip outlet from the freezer defrost drain. Ice cold water had been dripping on them for months, apparently both oxygenating them and flushing away the abcissic acid.
What doesn't kill them makes them stronger.

Karl K
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Re: Old seeds...

Post: # 66681Post Karl K
Mon Dec 18, 2017 12:23 pm

Don wrote:>> I probably would have tried with tepid water.

The solubility of oxygen in water is inverse to the temperature. I once had a baggie full of seeds germinate in the middle of winter in the refrigerator almost at the freezing point because they had been sitting under the drip outlet from the freezer defrost drain. Ice cold water had been dripping on them for months, apparently both oxygenating them and flushing away the abcissic acid.
If someone doesn't have a suitable defrost drain, hydrogen peroxide can be used to provide extra oxygen.

Babcock (1912)
"The best results have been obtained when the washed seeds were placed between filter papers that were moistened with a 3 per cent solution of hydrogen peroxide, which supplies oxygen in abundance and keeps molds from gaining the ascendency, until after the sprouts start. Treated in this way the fresh melon seeds germinate nearly as quickly and as well as dried seeds."

"In the case of corn, this change in viability is not due to preliminary drying, since soft kernels from the same ears, when immersed in hydrogen peroxide, all germinated within two weeks, without having been dried at any time. This indicates that direct respiration is the chief factor in bringing about those changes in the seed, that are essential to germination. Further confirmation of this view is supplied by failure of such seeds to germinate after being kept, for a similar period, in carbon dioxide or in boiled water, where no free oxygen was available."
http://bulbnrose.x10.mx/Heredity/Babcoc ... e1912.html

A quick google on hydrogen peroxide germination turned up 18,600 records that can provide further information.

Don
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Re: Old seeds...

Post: # 66682Post Don
Mon Dec 18, 2017 1:56 pm

>> hydrogen peroxide can be used to provide extra oxygen

True enough though 3% is, imho, too aggressive. I would still use very cold water and, personally, use a 1:20 dilution, or even a 1:100 dilution. Testae have stomata, you risk damaging the stomata and testae at higher concentrations. Just my opinion, of course. The objective is to keep a lot of O2 around the embryo, if the water is not cold the oxygen will just diffuse out as it is formed from the peroxide.
What doesn't kill them makes them stronger.

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