Galanthus breeding

[Martin Baxendale]

'Normal' in plants is diploid (as in animals) where the adult plant (or animal) has two sets of chromosomes. During the formation of reproductive bits the chromosome count halves, so a pollen grain  has one set of chromosomes and the ovule also has one set. When the pollen meets the ovule to form a seed, their two sets join again to create a new diploid adult with two sets of chromosomes.

Triploid is where the adult plant has three sets of chromosom es, tetraploid is where the plant has four sets, hexaploid is six sets, etc.

Triploids are not uncommon in the wild. They happen where a plant makes pollen which (due to a blip) still has both sets of chromosomes. This then pollinates a normal plant ovule with one set, creating a triploid seed with three sets of chromosomes. Tetraploids are rarer as a non-reduced pollen grain with both sets of chromosomes would need to meet up with a non-reduced ovulve with both chromosomes, and many plants are self-infertile, so that means the pollen finding another plant which has had the same blip, which is far less likely.

For breeding purposes tetraploids are desirable because (like triploids) the extra chromosomes tend to make them  bigger, stronger plants; but tetraploids are fully fertile while triploids are almost sterile, so you get lots more seed with tetraploids, which is what you need for breeding - obviously trying to breed with plants which produce hardly any seed is a pretty useless endeavour (except when like me you are trying to cross them to get your first tetraploids).

There have been investigations to find which snowdrops (wild and cuiltivated) are triploid and tetraploid. Many infertile triploids have been found, but virtually nothjing in the way of tetraploids.

[loes]

don`t you end up with 'Down'snowdrops!

[Brian Ellis]

Thank you Martin for an excellent explanation for thickies like me.   

One question that springs to mind is how do you tell whether it is triploid, tetraploid etc other than resorting to (I presume) cutting them up and looking under a microscope?

[Rob]

I'm attaching a general pic showing some autumn snowdrops next to the rhubarb, some colossus type top left, some atkinsii type just coming through in the foreground and maybe a couple of doubles top right.

[Martin Baxendale]

Thank you Martin for an excellent explanation for thickies like me.   

One question that springs to mind is how do you tell whether it is triploid, tetraploid etc other than resorting to (I presume) cutting them up and looking under a microscope?

Cutting them up and looking at them under a microscope is about it - or a more complicated thing called flow cytology analyses which tells you the DNA mass, from which you can deduce ploidy levels.

OR - if it's from a cross between known triploids or a known triploid onto a diploid, the resulting seedling is big, strong and healthy, with thick leaves, thick petals etc then it's most likely polyploid - and if it then won't set seed readily it's most likely a triploid, but if it sets lots of seed easily then it's quite likely a tetraploid.

For definite confirmation, though, you do need laboratory confirmation.

[rob krejzl]

Martin,

Oryzalin is considerably safer to use than cholchicine.

http://members.tripod.com/~h_syriacus/tetraploidy.htm - I'm sure that if you search you'll find newer references.

It might be worth mentioning that triploid lily hybrids can produce more seed if their partner is tetraploid. Would this be the case for snowdrop cv.s too?

[johngennard]

At the risk of offending Martin and noting his comments about 'Cotswold Farm' not being worth growing and also his desire to grow big strong snowdrops as with daffodils I consider that the big strong snowdrop that bears his name is not worth its place either.Last year I dug up a large patch with bulbs the size of daffodils and did'nt consider them worth passing on to anyone as they had produced so few flowers from such robust growth and I burnt them.Why anyone should be chargingŁ6.50  or even perpetuating 'Blaxendales's Late' is beyond me.

[Martin Baxendale]

At the risk of offending Martin and noting his comments about 'Cotswold Farm' not being worth growing and also his desire to grow big strong snowdrops as with daffodils I consider that the big strong snowdrop that bears his name is not worth its place either.Last year I dug up a large patch with bulbs the size of daffodils and did'nt consider them worth passing on to anyone as they had produced so few flowers from such robust growth and I burnt them.Why anyone should be chargingŁ6.50  or even perpetuating 'Blaxendales's Late' is beyond me.

I couldn't agree more. I didn't name it, and neither did anyone in my family. Baxendale's late was among various Gal. plicatus that Philip Ballard had from my mother and father's garden in the 1970s (Philip being husband of Helen Ballard of hellebore fame, both of them keen snowdrop growers).

My parents didn't rate it as particularly good but Philip wanted some as it was quite late flowering. And without their knowledge he passed it around as Baxendale's Late (after my father), which is what it's now known and sold as. I bought a couple of bulbs out of curiosity one year but let them die out as it really was a pretty poor plant, shy flowering and squinny when it did venture a flower. I certainly wouldn't recommend anyone to buy it.

I doubt I'll ever raise any snowdrops as big as trumpet daffs. It's just not in their genes to get as big as that. The wild trumpet daffs that the cultivars are raised from are, of course, much bigger than most wild snowdrops. I do like big snowdrops, as I think does everyone, but not that large      It's as much the vigour and disease resistance I'm after as the increase in size - but I doubt you'd ever get much bigger than some of the existing large cultivars. But there's a lot you can breed for - such as strong stems, late flowering and early flowering, new flower shapes, new markings, etc. However, as I say, vigour and disease resistance are equally important. I think it would be nice to have some new snowdrops that are really strong and disease free and fast to increase in the garden instead of needing cossetting as some of the older ones do. That doesn't mean I don't like the older cultivars either, nor that I'll stop growing them or expect anyone else will.

[Martin Baxendale]

Rob, thanks for the link re. Chemical treatments to induce tetraploidy - I've had a quick look and it's very interesting. I'll be studying it at my leisure after the New Year festivities.

[Martin Baxendale]

John, I didn't say Cotswold Farm wasn't worth growing, just that I didn't think it was any great shakes. It's nice enough, but not a first-rank snowdrop. I don't know if Ruth Birchall named it or someone else. Actually, I like the recent idea that people should ask permission before naming a snowdrop after someone. There've been some cases where a snowdrop was named after a grower and it turned out that grower didn't much like the idea (didn't like the snowdrop much) and Baxendale's Late is a perfect example. If Philip Ballard had asked my parents they'd have said no thanks.

[Paul T]

Martin et al,

I would love if the postings within this thread about breeding Galanthus could perhaps be put out into their own discussion thread, so that they aren't in under a month (i.e the pre January).  That way we can continue to contribute to the thread for time to come.....

I have an associated query...... I have never been able to find any pollen on my snowdrops, except on VERY rare occasions.  Is there a time of day, time since opening, temperature etc that triggers pollen release?  Maybe it is just too warm when they're open here and the pollen just shrivels quickly?  I have intended to try some hybridising, but I haven't even managed to self-pollinate the darn things usually, as I can't find pollen on them.  I think that only twice have I ever found pollen.  Now I must admit I haven't been out checking at various times of day, or out with the torch at night, so I'm obviously not THAT dedicated!!    I'd just like to try it successfully for a change.

[Brian Ellis]

Martin is there any correlation between a plant being diploid, triploid etc and the ease of gaining bulbils from chipping/twin-scaling?  I cut Primrose Warburg, Three Ships, Wendy's Gold and others a couple of years ago as an experiment and certainly the yellows were not as fecund as the others, but I don't know whether it is because I chipped the expensive ones (heart in mouth) and tried my hand at twin-scaling the common ones.  Hopefully I will have some decent clumps in a shorter time.

[mark smyth]

what can be seen when a leaf is cut?

Paul it's possible that the pollen on your snowdrops falls too quickly due to warmth. When I bring mine inside to force them to open I see pollen falling out when I touch the flowers

[Paul T]

So does that mean you bring yours in for their first opening, or does it mean that there is pollen each morning?

[mark smyth]

I bring them in so they open for me to take a photo. I assume warmth makes the pollen fall