distinguishing snow and snap peas

[diane]

I crossed some purple, yellow and green snap and snow peas in the spring, germinated the seeds while they were still green, and now have pods.

I want to keep all the seeds for growing the next generation. Is there a way I can tell what type of pods I've got without destroying them?

[raymondo]

If this is first generation, F1, from the cross, that is pods from the crossed seeds, then any with at least one snow parent will be a snow type pods. It is in the second generation, F2, that segregation snow/snap will occur. In other words, it is the seeds you are about to collect that will start separating out.

[diane]

Thanks, Ray.

Then, I will need to know how to distinguish the next generation.

I'm just amazed that I can grow three generations in a year (or maybe even four.)

I can remember talking to a breeder (of what, I've long since forgotten) who grew one generation in Canada and the second in Costa Rica. It would be fun to go to Costa Rica, but sure is a lot cheaper doing it all at home.

[Joseph Lofthouse]

Aug 22, 2012 23:24:42 GMT -5 diane said:

I crossed some purple, yellow and green snap and snow peas in the spring
...
Is there a way I can tell what type of pods I've got without destroying them?

I crossed a yellow snow pea and a purple snap pea last summer. All of the (F1) descendants were very fibrous podded: Not any kind of edible-pod pea. I'm expecting that if I have enough seed during the next growing season that some (of the F2) may end up as snap peas again, and some may end up as snow peas... I guess it all depends on how many genes are working together to produce the various types, and whether I plant enough seeds for the statistics to work in my favor.

[raymondo]

Actually, Joseph has a point. It is possible to get fibrous pods in the F1. I'd forgotten that the snow type can come from either of two genes. If the snow has the appropriate gene versions or alleles for one gene and the snap has the snow alleles on the other gene then the combo will be fibrous. Apologies Diane.
In any case, it's the next generation you're interested in. I find growing the original parents alongside helpful. Snaps are pretty easy to distinguish from snows after only a short time. They tend to be more rounded in the 'waist' sense and just get more plump as time goes by. The snows will eventually fill out too but you'll quickly learn the difference, especially if you grow a couple of the original parents alongside. Distinguishing snaps from fibrous types is simply a matter of eating a few pods as they grow. The fibrous ones will be obvious.
Good luck with it and keep us posted on progress. You too Joseph. I love reading about other people's projects.

[Joseph Lofthouse]

I generally only get one crop per year of peas. So for this year my F2 pea seed has been harvested and run through the freezer twice to kill weevil. I'm not expecting to do anything else with my red-podded pea project until next growing season. However, I did plant some F1 seed of an attempted cross between my earliest shelling peas and Austrian winter peas (which survived the winter as small plants). Some of those are currently blooming. Our fall frosts will be upon us in a jiffy, so if there is any news to report I'll let you know. I'm not likely to post anything if they get frozen before producing seeds. If they don't get frozen, I'll plant the F2 seed this fall.

I have really come to like surveyor's ribbon and a permanent ink marker for use while plant breeding. I can go out into the field, taste a sample of each plant and write notes on the ribbon about what I thought, or what I saw, or smelled, etc... Sure makes it easier a month or two later when it's time to pick seeds.

I also attempted a few crosses between my earliest shelling peas and yellow podded snow peas and purple podded snap peas... However surveyors tape was not appropriate for marking them (it fell off), so some of the seed from the crosses may have got incorporated into my earliest shelling pea population. I aughta be able to tell which ones if any of the blossoms have purple coloration in them. Makes me not want to share the seed... I'd hate to loose a cross after all that effort. But can I really plant all the earliest seed that I grew?

[templeton]

Diane,
As Ray says, and you might already know, pod fibre is controlled by two recessive genes, denoted as p and v - they both reduce pod fibre, but distribute it in different areas on the pod.
Snap peas have the reduced fibre - so they are palatable - but also include a recessive gene for 'fleshy pod wall', denoted n.

I'm struggling with this a bit myself at the moment, trying to figure out if my F2s are snows or fibrous.
One experiment I tried last season was to nip a few millimtres of pod off the end of the developing pod, but leaving the rest of the pod to develop seed. It's a bit tricky telling if they have fibre or not, because of the string in the suture (pod seam). But at least you can test for taste. The one or two pods I tried this on last summer went on to develop proper seeds in the pod with no problems, apart from a slightly chewed end. Try this on some of your non-crosses to see if it works for your varieties and climate.

Growing snows and my F2s together is useful - the snows as the pods develop try to stay flat and the developing peas inside bulge inside the pod. Normal fibre podded pea pods just swell into a continuously fat pod.

The snaps to my eye seem to be much thicker even as early as petal drop. This will tell you if they have nn for thick pod walls, but as Ray says, they might be carrying a dominant V or P, which would give a fibrous but thick pod wall.

I think good snows, and good snaps should be homozygous for both v and p, that is maximum fibre reduction, but I can't be sure.
My first F2s are just developing pods at the moment.

One issue with growing in off seasons can be poor seed production, and for me at the moment, disease and poor seed set.
I grew a few experimental F1s last summer in shade from my spring crosses, and while I got a few seeds off, they really struggled. I planted the resulting seed - we have relatively mild winters with no killing frosts - but I have had some nasty black spot and powdery mildew, and some of the F2s just will not set seed even though they are flowering madly. So while 4 crops a year are possible, its not optimal. Growing out crosses in sub optimal conditions will exert some selective pressure for adaptation to these less than desirable growing conditions - not a great idea unless that is what you want. hmmm, should do a blog post on it (he shamelessly self promotes ;D )

Sorry, raving a bit - I've been out all day creating beds for my spring growouts - hundreds of seed, a dozen different crosses to explore, F2s ripening everywhere across the beds, and not enough space!
T

[templeton]

A further question on this - apart from chewing up pods, is their an examination methodology that will allow visual discrimination between the two fibre reduction genes, v and p?
The John Innes pisum database says
v..."Removes most of the sclerenchymatous membrane from the inner pod wall. Edible podded. Small patches of sclerenchyma (slightly shiny) on inside of pod wall, or a thin layer unevenly distributed, often only towards both ends of the pod. See also p ."

and p..."Removes most of sclerenchymatous membrane of inner pod wall. Edible poded. P V normal parchmented pod; p V strip of sclerenchyma; P v inner membrane reduced to patches of sclerenchyma; p v entirely without parchment. Spontaneous mutation rate from p to P from 0.05-0.2%."

I've had a look at a few pods over the past week, and can't visually see parchment or lack of it - I've tried dried down pods, just fertilised pods, maturing pods - obviously I don't know what I'm looking for. Any advice on this? Microscope? Staining?
T

[raymondo]

Although I did well in my plant anatomy theory exam my practical skills left, and still leave, a lot to be desired!

[templeton]

Yesterday I culled all the green podded peas in my F2 purple pod growout, and reserved the maturing pods. My F1 should have been PpVv, homozygous for the two genes that produce pod fibre.

That means 1/4 of the F2 plants should have been pp, one quarter vv, and the rest fibrous. I just pooled all the pods, then sat down in front of the TV with a scalpel, and slit open the edge of each pod. The pods were at different stages of maturity, mostly quite small.
The inside walls of them were all identical to my examination. By folding the fresh pod wall inwards it was easy to see the parchment layer on the inner side of the pod wall - in the fully fibrous pods it was possible to gently peel the clear fibre layer from the inside by peeling one broken bit from the other.

There were some pods that had much thinner layers, the layer snapped rather than peeled away. With care, you could still see the fibre layer, it was just much thinner. Taste tests confirmed the visual evidence.

However this morning I went and picked some real snows to compare. I tried 'chinese snow pea' and Golden Podded. The chinese snow pea (from a research station accession so i have no details on its variety name) was a tasty, single flowered snow, that broke readily with no fibre.
GP has always struck me as a semi fibrous snow from chew tests. The pod snapped in half, no fibre layer on the inside of the pod, but dentating it softly between my front teeth (sorry for the gruesome detail) it was possible to extract a fibre layer from the outside of the pod. I then tried it with the snow - same thing, but more palatable.This fibre business is not as straightforward as Mendel and co would have us believe. Palatability for fibre might have some other factors going on.
T

[steev]

So there may be more than one fiber layer determined? Interesting. Clearly that could be determined by different genes, if so. Plant science marches on.

[templeton]

I'm not sure what is going on Steev. I think I've never really thought about fiber in pea pods before, so it's probably a case of look and you'll start seeing new stuff.
My totally layman guess is that there is an unpalatable parchment layer inside the pod that is regulated by the advertised genes, but that there might be some fibre in the pod wall that is not regulated by these genes - perhaps its always there, and I've never thought about it before, or maybe its an environmentally or age regulated factor. I'll start paying a bit more attention about what i put in my mouth
T

[iva]

Read through the whole thread, and am now even more confused than before. Putting genes aside, how do you tell them apart?
Ok, so snows remain thinner and the seeds bulge out more? How about snaps? And what are then sugar pods - snows or snaps?

Sorry for the dumb questions, but I'm just getting into peas myself and want to know as much as possible. If I don't know what they are, I might be using them the wrong way. Help much appreciated...
To make things more interesting, here is a list of varieties I've grown so far, can anyone please tell me what type of peas these are?
Dwarf Grey Sugar
Curruther's Purple Podded
Golden Sweet
Thomas Laxton
Laxton's Exquisite
Little Marvel
Dwarf Telephone (Carter's Daisy)
Parsley pea
Rondo
Capucijners
Blauwschokkers

Thanks so much!

[Joseph Lofthouse]

snap pea: Have thick walled pods. Can be snapped in half. Pod is easy to chew and not fibrous. (Sugar snap is the name of one cultivar.)
snow pea: Have thin walled pods. Easy to chew and not fibrous (may have a string attached to stem.)
Shelling pea: Immature peas taste sweet. Mature dried peas are wrinkled.
Soup pea: Not good to eat by any of the above methods. Pods are normally fibrous. Immature peas are not sweet.

Little Marvel: Shelling
Capucijners: Soup

[iva]

Thank you sooooo much, Joseph!! That just about explains everything to me