|
|
Post by oxbowfarm on Dec 18, 2017 7:18:02 GMT -5
You have to grow out 30+ plants to find a naked segregate. . . It might be a bit easier with a backcross than a selfed plant. Anyone know how many genetic loci are involved? (These numbers suggest at least two.) Three. At least two of them are recessive and so need to be homozygous, that's why backcrossing probably would reduce the number of F2 plants needed, but I actually haven't done a Punnet square for that one. three trait Punnet square is a PITA. |
|
Day
gardener
When in doubt, grow it out.
Posts: 171
|
Post by Day on Dec 18, 2017 18:45:47 GMT -5
oxbowfarm - Yeah the f2 would definitely be my biggest hurdle, as I cannot mass plant in my wee 1200ish sqft garden. I'd probably end up only able to plant a half dozen plants each season at most (keeping room for my other projects), which would severely slow the selection process. I have had some luck in the past with mass sowing a lot of squash seeds in a very close block, as you would corn, then viciously 'culling as they grow' based on earliness, fruit shape, color, whatever I'm after. There are usually so few left they end up with quite decent growing space. Of course, this would be much harder with nakeds, unless it's possible to chop immature fruit quite early to identify the seed type.
|
|
|
|
Post by oxbowfarm on Dec 18, 2017 21:26:39 GMT -5
oxbowfarm - Yeah the f2 would definitely be my biggest hurdle, as I cannot mass plant in my wee 1200ish sqft garden. I'd probably end up only able to plant a half dozen plants each season at most (keeping room for my other projects), which would severely slow the selection process. I have had some luck in the past with mass sowing a lot of squash seeds in a very close block, as you would corn, then viciously 'culling as they grow' based on earliness, fruit shape, color, whatever I'm after. There are usually so few left they end up with quite decent growing space. Of course, this would be much harder with nakeds, unless it's possible to chop immature fruit quite early to identify the seed type. It might be faster to backcross to the naked parent vs self the F1, and then do that again to the F2. Then start growing out the progeny. The F3 seed would still be 25% of the hulled genotype, so you should still have plenty of segregation for seediness etc? It does seem like increasing pepita yield per fruit is a useful goal, but I think its also just about the hardest thing to do. The fat and protein the plant has to produce to build the seeds are way more effort than fruit flesh, which is basically water plus starch and cellulose. |
|
Day
gardener
When in doubt, grow it out.
Posts: 171
|
Post by Day on Dec 18, 2017 22:21:26 GMT -5
It might be faster to backcross to the naked parent vs self the F1, and then do that again to the F2. Then start growing out the progeny. The F3 seed would still be 25% of the hulled genotype, so you should still have plenty of segregation for seediness etc? Very smart - so, tossing the idea around, say I use Howden pumpkin (biggest pepo I can think of), you'd be suggesting a Pepitas x Howden = F1 x Pepitas = F2 x Pepitas = growout would result in apx 25% hulled which can be culled, and the remaining 75% selected for size/seediness/etc. Pepitas is also an F1, which may need some factoring it. I grew two plants this year with no other pepos present, so in theory I should have pure seed from a pure of selfed Pepitas to grow out this spring and observe any segregation. It does seem like increasing pepita yield per fruit is a useful goal, but I think its also just about the hardest thing to do. The fat and protein the plant has to produce to build the seeds are way more effort than fruit flesh, which is basically water plus starch and cellulose. A very good point I hadn't even thought of -- so the first step might be finding out approximately how many seeds one can expect in a large pepo such as howden vs. pepitas; which is to say for each additional pound of squash, how many more seeds can be expected. It may very well be a diminishing return, which would make for both a very difficult/long term and ultimately uninspiring breeding project. Lots to think on ~ |
|
|
|
Post by troppo on Dec 18, 2017 23:20:07 GMT -5
I've often thought about conducting a similar project over here in OZ as we are pretty limited compared to you guys with different varieties. One of my thoughts was what would be the resulting effect of increasing fruit size on over yield? As such, does number of fruit per plant decline when selecting for size? Would it be better to select instead for total seed yield per plant rather than individual fruit size? Would it also be better to select for a bush-type plant structure so as to allow narrower crop rows/increased plant densities?
|
|
Day
gardener
When in doubt, grow it out.
Posts: 171
|
Post by Day on Dec 19, 2017 1:19:04 GMT -5
One of my thoughts was what would be the resulting effect of increasing fruit size on over yield? As such, does number of fruit per plant decline when selecting for size? Would it be better to select instead for total seed yield per plant rather than individual fruit size? Would it also be better to select for a bush-type plant structure so as to allow narrower crop rows/increased plant densities? I think seed yield per plant could also be a very smart way to go about it. There are so many other variables that could also come into play, like length of growing season. If the growing season is short there may only be time for a plant to produce a few fruit before frost shuts it down, in which case larger size fruit could be advantageous. On the other hand, in a long season, copious production of small fruits may beat out much slower production of large fruits. And then weighing which would be more useful for consumption -- a larger quantity of seeds less frequently, or frequent small amounts. As for bush vs. vine, I planted two plants of vine type mini red turban last year. I got approximately twenty five between the two plants. The fruit ranged in size from the size of a golf ball to the size of a slightly flat basketball. I also planted 3 bush type buttercup squash and got approximately 3 fruit per plant, all relatively uniform in size, unlike the turban. Though the majority of the turban squash were approximately the same size as the buttercups. The bush buttercups each took up about 1/3 the space of the turban, so by that math they were much less productive for the space they did take up per fruit, though that would have to take into account the several oversized and undersized turban squash. But I don't know if that's typical of bush vines, or if that's simply how it worked out in my garden. oxbowfarm - how is the Ned Kelly's vining habit? |
|
andyb
gardener
Posts: 179
|
Post by andyb on Dec 19, 2017 2:05:17 GMT -5
Day, for purely practical reasons, why not grow the smallest bush plants you can? That way you could keep the population size up and avoid having to spread each generation over several years.
|
|
|
|
Post by oxbowfarm on Dec 19, 2017 7:00:18 GMT -5
Day Ned Kelly is a pretty standard long vining indeterminate. I don't think there are any genes for bush habit in it, but Thelma Sanders and Lady Godiva are both indeterminates. Here's the original naked F2 plant, you can't see much of it but you can tell its a long vine.  In terms of the backcrossing idea, I'm not sure if I am reading you correctly, but I was meaning to do one backcross to the naked parent after the original cross. I'd say that should give you approximately 75% of the nuclear genome coming from the naked parent. I don't know if it wouldn't be better to use the hulled parent like Howden for the mother of the original cross, so you'd be keeping the cytoplasm from Howden. I remember Carol Deppe writing about using Howden as a mother plant in her Delicata/Howden cross (Snack-something? she never released it) that she talked about in BYOVV specifically to keep the "vigorous" cytoplasm from Howden.
|
|
Day
gardener
When in doubt, grow it out.
Posts: 171
|
Post by Day on Dec 19, 2017 14:12:11 GMT -5
andyb - I think that could be a very clever way to handle the population size grow out issue. I wonder though, if the goal is to breed for large size/many seeded hull less fruits, how many bush options I have. I can't think of a large size pepo that grows bush, and to the best of my memory I haven't seen a hull-less variety gadvertising bush vines. It might be something that would have to be breed in, which might cause more a headache, though I agree it could be very beneficial down the line in terms of saving space. Actually according to cuke.hort.ncsu.edu/cgc/cgcgenes/gene14squash.pdf bush is dominant (always though it was recessive) so it may not be that big of a detour to breed it into the line, though breeding the other imported material out might prove the bigger challenge. oxbowfarm - I'm going to repeat some things and might sound silly, so forgive me if I've misunderstood or our wires crossed somewhere. When you say the picture is of the original naked F2 plant, I read that as: I planted the F2 seeds and this grew, with the seeds inside it being F3. Or is it that the picture is the F1 grow out, with the seeds inside being the F2? I don't have many people in my life willing or able to talk plant genetics with me, so while I know a lot of genetic terms, I sometimes struggle with how they're used conversationally. The info about Howden/Deppe is extremely useful - thank you! I've read several (but not all) of Carol's books but don't remember that bit. Though I wasn't breeding, or intending to breed, pepos at the time so I may not have stored it in my long term memory. If I start on this project, perhaps I will do exactly as you suggest and use Howden as the mother to get the most out of the variety, since I won't be backcrossing to Howden. I feel like I've hijacked this board -- I've started a thread HERE so as not to clutter this one up with side tangents and my own personal project
|
|
|
|
Post by tpeltan on Jan 5, 2018 13:06:11 GMT -5
oxbowfarm - Yeah the f2 would definitely be my biggest hurdle, as I cannot mass plant in my wee 1200ish sqft garden. I'd probably end up only able to plant a half dozen plants each season at most (keeping room for my other projects), which would severely slow the selection process. I have had some luck in the past with mass sowing a lot of squash seeds in a very close block, as you would corn, then viciously 'culling as they grow' based on earliness, fruit shape, color, whatever I'm after. There are usually so few left they end up with quite decent growing space. Of course, this would be much harder with nakeds, unless it's possible to chop immature fruit quite early to identify the seed type. It might be faster to backcross to the naked parent vs self the F1, and then do that again to the F2. Then start growing out the progeny. The F3 seed would still be 25% of the hulled genotype, so you should still have plenty of segregation for seediness etc? It does seem like increasing pepita yield per fruit is a useful goal, but I think its also just about the hardest thing to do. The fat and protein the plant has to produce to build the seeds are way more effort than fruit flesh, which is basically water plus starch and cellulose. While it might be faster it also decreases the share of genes from the hulled parent (1/8 after two backcrosses) - and that was the reason for crossing at the first place, wasn't it? |
|
|
|
Post by diane on Jan 5, 2018 14:55:11 GMT -5
Day I don't know if it wouldn't be better to use the hulled parent like Howden for the mother of the original cross, so you'd be keeping the cytoplasm from Howden. I remember Carol Deppe writing about using Howden as a mother plant in her Delicata/Howden cross (Snack-something? she never released it) that she talked about in BYOVV specifically to keep the "vigorous" cytoplasm from Howden. Carol wasn't crossing for naked seeds, but for a bigger delicata with thicker flesh. That's why she used a pumpkin. Will Bonsall wrote: the naked seed trait is maternal and recessive, so crosses must be made on the hulless parent (assuming only one is hl) and then backcrossed to recover the hulless gene. Will Bonsall wrote "Oilseed Pumpkins" in the MOGFA periodical (Maine Organic Gardeners & Farmers Association). Read more: alanbishop.proboards.com/thread/9226/seeded-hulless-pepos-crosses#ixzz53LDaFotF |
|
|
|
Post by oxbowfarm on Jan 5, 2018 15:54:05 GMT -5
diane She also specifically mentioned using Howden as the mother to preserve the Howden cytoplasm. Thats the aspect I was getting at. Naked seed is maternal, but that doesn't mean you can only use the naked seeded parent for your female parent. Offspring will segregate for naked either way. I was suggesting that Day use the pumpkin as the mother for a similar purpose of retaining the cytoplasm from the pumpkin side. I like WIll Bonsall, but when it comes to breeding naked seeded squash, I listen more to the pros like Brent Loy and Michael Mazourek. tpeltan The problem is number of progeny you have to grow out, the more backcrossing you do the fewer segregates you have to grow out to find a naked seeded one. If Day had more room then it wouldn't be necessary to backcross so much. It really sets back your project if none of your F2s or whatever have the phenotype you are looking for.
|
|
|
|
Post by tpeltan on Jan 8, 2018 10:48:45 GMT -5
diane She also specifically mentioned using Howden as the mother to preserve the Howden cytoplasm. Thats the aspect I was getting at. Naked seed is maternal, but that doesn't mean you can only use the naked seeded parent for your female parent. Offspring will segregate for naked either way. I was suggesting that Day use the pumpkin as the mother for a similar purpose of retaining the cytoplasm from the pumpkin side. I like WIll Bonsall, but when it comes to breeding naked seeded squash, I listen more to the pros like Brent Loy and Michael Mazourek. tpeltan The problem is number of progeny you have to grow out, the more backcrossing you do the fewer segregates you have to grow out to find a naked seeded one. If Day had more room then it wouldn't be necessary to backcross so much. It really sets back your project if none of your F2s or whatever have the phenotype you are looking for. But what is the sought-after phenotype? Is naked seed enough? If the space is limited why not to consider bush type as (one of) the goals? This will alow to pack more plants on the same space. The gene for bush growth should be "dominant to vine habit" so there might even be some (66 percent) chance to return to vine habit in next generation. |
|
