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Post by philagardener on Feb 7, 2018 21:08:06 GMT -5
If you don't like what happens, just dig into depths of the freezer and start for the first time, all over again . . .
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Post by reed on Feb 7, 2018 21:29:27 GMT -5
I turned lots of modern hybrids loose in my sweet corn. I figured the people who breed them picked the parent varieties cause of good performance in one area or another. Maybe stalk strength, good tip cover or disease tolerance, who knows. I just figure it is a way for me to introduce high quality genetics into my mix. I only include su and se varieties and of course no GMO or patents.
The only negative I see is most modern sweet corns are bred for large ears with lots of rows and I really prefer fewer number of rows. I don't think that qualifies as feeble, it's just a trait I'll need to select back out in future while at the same time hopefully keeping the qualities I like.
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Post by rowan on Feb 8, 2018 0:25:47 GMT -5
Many people are so negative to modern commercial hybrid due to misinformation and lack of understanding of genetics, not because of any inherent problems.
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Post by reed on Feb 8, 2018 5:48:28 GMT -5
Most people around here and I guess in general don't known the difference between hybrid and GMO. Then there is all the hype about preserving "heirlooms".
I have mostly stopped de-tasseling but have done it both ways to try to mix things up a little better and keep as much diversity as possible. I tag my seed ears as su or se but at this point that only means the seed I originally started with was one of those. I alternate su / se rows when planting.
I figure the hybrid growers have to keep both parent lines as pure inbreds. I don't see a lot of difference between that and an inbred OP. I just look at it as a head start for me since someone else already did the selecting and breeding of the F1. I'v only been working on my sweet corn for four or five years but I'm very happy with what is starting to come out of it. At first I tried to keep seed from mothers of every variety I started with but now I'm selecting more on phenotype.
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Post by oxbowfarm on Feb 8, 2018 7:39:09 GMT -5
toomanyirons I think you are over-emphasizing to yourself that hybrid corns/inbred lines are "feeble". That idea comes from the classic explanation of hybrid corn, which used very "feeble" inbred lines to produce the resulting hybrids. The "feebleness" doesn't say anything specific about the genetic quality of the plant, it is simply a result of inbreeding depression in a crop that HATES to be inbred. Modern inbred lines are pretty much not "feeble" the way they were a century ago. They've selected and improved the inbreds over many generations to the point where they are very nice strong corn plants not visibly different in vigor and strength from many OP varieties. I could make an argument that many OP varieties are much more "feeble" than the inbred lines due to them being maintained improperly and poorly selected. There are lots of OP varieties for sale on the home gardener market that are basically randomly selected. cough cough Glass Gem cough cough At least with an inbred line you know they've been actively maintianing it and selecting it. The main issue with modern inbreds and/or hybrids is what traits are they selecting for, and do those match your goal? I don't know exactly what kind of corn project you want to do, but it sounded like a popcorn project? I'd have absolutely zero hesitation using a modern non-GMO hybrid as part of a popcorn breeding project. It will definitely NOT give you "feeble" genetics.
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Post by jondear on Feb 8, 2018 10:25:39 GMT -5
I may be wrong, but once two parental lines are crossed,to make the F1, they aren't really inbred anymore.
Thoughts?
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Day
gardener
When in doubt, grow it out.
Posts: 171
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Post by Day on Feb 8, 2018 12:13:43 GMT -5
Day that is sure strange. I have read a lot about strange things that can happen by planting corns outside of their daylength zones. Strange things can also happen simply by growing a corn plant in a pot, and by intentionally damaging various areas of a corn plant in certain ways at certain times during its growth period. The particular branching trait I grew wasn't as unique as I thought when I originally harvested it. It seems not a trait due to exposure to my strange 'northern' garden and growing conditions, though I don't doubt there are traits out there that due appear as a result of planting in pots or outside of daylength. So hopefully that means I can expect an extra fertile garden this year  |
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Day
gardener
When in doubt, grow it out.
Posts: 171
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Post by Day on Feb 8, 2018 12:51:38 GMT -5
But if the seed produced from that F1 generation is saved and replanted the F2 plants will not show the same vigor as in the F1, so is that the negative traits of the inbreeding of the parentage carrying over or is it because the crossing of the F1 plants produce open pollinated strains that are inherently weaker than that F1 hybrid? My understanding is that the main theory behind hybrid vigor (Heterosis) is heterozygosity. In this sense, crossing two inbred strains that are very similar and with similar weaknesses (especially if those weaknesses translate into homozygous recessives) would not make a hybrid of significant vigor or improvement on the parents. Crossing two very genetically different inbreds, matching up the strengths and weaknesses of each parent carefully (taking into account what is dominant and recessive) will, on the other hand, create a hybrid of much greater 'quality' than the parents and also that of the first F1 example from closely related parents. So the F2 loss in vigor would be the result of the heterozygous genes of the F1 (Xx), segregating in the F2 into XX, Xx and xx if the F1 plant is selfed. From my study of the issue, my take-away is as follows -- hybrid vigor can be useful, but the most important issue is ensuring the genes you need/want match up the way you want them to. If you'll allow me to luxury of a human example: Let's say a man from Papua New Guinea and a woman from Iceland (both of whom likely have very different genetic backgrounds) decide to have children together -- those children have very high heterosis. However, let's say the Papua New Guinean father and Icelandic Mother are also both carriers of the autosomal recessive for sickle cell anemia ( ok, this would make them heterozygous for that trait, but let's table that). If so, then their child will still have heterosis from the combinations of all the other varied genes... but could also have sickle cell anemia. The latter of which is will likely negate any benefits the individual would have derived from their genetic heterozygosity. So while hybrid vigor can be an important factor in health and growth, the individual genes in question are often more important. I know of founder's effect, or more colloquially called Founder's curse, if the trait is negative. In horses, an example would be the Carthusian strain of the Andalusian breed (Pura Raza Espanola (PRE)). |
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Post by reed on Feb 8, 2018 13:39:44 GMT -5
But if the seed produced from that F1 generation is saved and replanted the F2 plants will not show the same vigor as in the F1, so is that the negative traits of the inbreeding of the parentage carrying over or is it because the crossing of the F1 plants produce open pollinated strains that are inherently weaker than that F1 hybrid? My understanding is that the main theory behind hybrid vigor (Heterosis) is heterozygosity. In this sense, crossing two inbred strains that are very similar and with similar weaknesses (especially if those weaknesses translate into homozygous recessives) would not make a hybrid of significant vigor or improvement on the parents. Crossing two very genetically different inbreds, matching up the strengths and weaknesses of each parent carefully (taking into account what is dominant and recessive) will, on the other hand, create a hybrid of much greater 'quality' than the parents and also that of the first F1 example from closely related parents. So the F2 loss in vigor would be the result of the heterozygous genes of the F1 (Xx), segregating in the F2 into XX, Xx and xx if the F1 plant is selfed. From my study of the issue, my take-away is as follows -- hybrid vigor can be useful, but the most important issue is ensuring the genes you need/want match up the way you want them to. If you'll allow me to luxury of a human example: Let's say a man from Papua New Guinea and a woman from Iceland (both of whom likely have very different genetic backgrounds) decide to have children together -- those children have very high heterosis. However, let's say the Papua New Guinean father and Icelandic Mother are also both carriers of the autosomal recessive for sickle cell anemia ( ok, this would make them heterozygous for that trait, but let's table that). If so, then their child will still have heterosis from the combinations of all the other varied genes... but could also have sickle cell anemia. The latter of which is will likely negate any benefits the individual would have derived from their genetic heterozygosity. So while hybrid vigor can be an important factor in health and growth, the individual genes in question are often more important. I know of founder's effect, or more colloquially called Founder's curse, if the trait is negative. In horses, an example would be the Carthusian strain of the Andalusian breed (Pura Raza Espanola (PRE)). That is pretty much how I understand it as well. Inbreeding depression (specifically to corn) it is when a single phenotype or I suppose actually genotype is grown in small populations. I'm guessing there is basically a certain minimum amount of variation within any particular strain and apparently not all of this minimum is contained in any small set of plants. That's why and again this is just my understanding if you save seed of a single strain from less than 200 plants you are likely losing some of that necessary minimum and the crop degrades. I can't grow enough, especially of sweet corn to accomplish that and still have any left to eat. My theory on getting around it is for my crop to be from many varieties. Hybrids and hybrids of hybrids on and on. Carol Deppe said that the wider a cross the less plants are needed to make a new strain, even to the point of a single ear or even a single kernel but only if the cross is wide enough. That's a lot like what Day said. I'm guessing what Carol means by wide cross is that the parents are vastly different. Two similar sweet corns or two pop corns for example probably don't fit that bill. As far as effects of inbreeding depression continuing in future generations after cross(es) are made, I don't think that is the case. You have just preserved what you liked about the depressed strain in a renewed form and can select for it again. As long as the cross is fairly wide the depression is cured immediately. If your cross isn't wide enough then simply involve more strains. It's logical I think that once you settle on a new mix and start selecting for specific traits the slide toward depression begins anew, at least in my case, case cause I only grow small populations. Still, by mixing over 50 kinds of OP and about 20 F1 hybrids (two for the price of one) and including even non sweet (which were detasseled at first) I figure as long as I save from say a minimum of ten plants each year and add in seeds from prior years the slide to noticeable depression can be effectively eliminated even though I select for particular traits like flavor, row number and quick maturity. I figure as long as a gardener is OK with slightly different flavor, color and the like from season to season or even plant to plant then the issue of inbreeding depression for small scale seed saving, is eliminated indefinitely. Also if I trade my seeds to someone who grows larger populations they could easily select more specifically for whatever they like. I'm basically just doing the same thing that Alan and Joseph did with AD, I'm just re-Hooserizing it a little and selecting on slightly different criteria. |
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Day
gardener
When in doubt, grow it out.
Posts: 171
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Post by Day on Feb 8, 2018 14:42:10 GMT -5
As far as effects of inbreeding depression continuing in future generations after cross(es) are made, I don't think that is the case. You have just preserved what you liked about the depressed strain in a renewed form and can select for it again. Well said. |
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Post by walt on Feb 8, 2018 16:49:37 GMT -5
This has been an amazingly intelligent and informed discussion. I expect such to break out here now and then. That is why I try to get online and see what is going on nearly every day.
So I will add my $0.02.
Allard, Robert W., Principles of Plant Breeding. This was a textbook for 3 grad courses in plant breeding I took. That was back in 1977-78. It is still in print for good reason. And while it covers some complicated topics, it is written in clear English. I re-read it every winter for a couple of decades and still get it out. I learn something new every time. Yet a beginner will get a lot on the first reading. Used copies are available from Amazon.
So, he has a chapter on synthetic varieties, using examples from corn. A synthetic variety is a variety synthethised from inbred lines (of corn in this example, but the method works for any cross fertilized crop).
To decide which inbreds to use to make a synthetic variety, take a bunch of inbreds and make crosses in all combinations. Those that make the best F1 hybrids are then intercrossed in all combinations and the result can then be used as an open-pollinated variety.
The yield of the resulting synthetic will be the mean of the F1s used, minus (the mean of the inbreds divided by the number of inbreds). That doesn't look exactly right. I'll try to find the equation and get back to you.
In practice, 8 to 12 inbreds has generally been found to be the optimum number of inbreds. So no inbred should be more than 1/8 of the population. An F1 hybrid corn is the result of two inbreds, typically, so it shouldn't be more than 1/4 of the population. So Too many irons should use a backcross to his open-pollinated population. Or at least that would be predicted to be best. The real world doesn't always conform to mathematical models.
2 other papers on corn breeding may be of interest.
Clarence Genter (1967) "Inbreeding without inbreeding depression" In John Southerland (ed), Proceedings of the "Twenty-second Corn and Sorghum Research Conference. Washington D.C. American Seed Trade Association.
Clarence Genter (1982) "Recurrent selection for high inbred yields from the F2 of a maize single cross" In Harold D. Loden and Dolores Wilkinson (eds) Proceedings of the Thirty-seventh Corn and Sorghum Research Conference Washington D.C. American Seed Trade Association.
What Dr. Genter did was take a locally adapted and locally recommended commercial F1 hybrid corn variety. He grew out the F1 as usual. But starting in the F2 he started crossing pairs of plants, each pair from one ear. . He would grow 100 such sib crosses. He'd run replicated trials and select the best 10, or was it 16?, pairs and intercross them to make the next generation.
In just a few generations, about 5 if I remember right, one of his F5 crosses outyielded the origional F1 variety which was grown as a controle. By the F10 or so, all the sib cross families were outyielding the origional F1. Yet given the population size, his population was as inbred as a single F3 plant grown from a single F2 plant.
And when outcrossed to unrelated corn, his inbred population showed little or no hybrid vigor.
By the way, corn grown at high altitude in the Andes where corn fields are small, show little or no inbreeding depression when selfed, and little or no hybrid vigor when outcrossed. Corn can adapt to inbreeding as well as tomatoes have. Heck of a deal.
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Post by oxbowfarm on Feb 8, 2018 18:29:35 GMT -5
I know you have negative opinions regarding Glass Gem corn. I am abivalent to the whole Glass Gem wondercorn hype thing but you really have me wondering about the true story behind GG. If I may respecfully ask, what am I missing that bothers you (and many others) so much about it? Again, I am just curious. I mean, it seems to be strictly an ornamental corn so why is there any issue regarding its provenance? There is a valid market out there for pretty ornamental corn, even if it is just a vanity thing. I guess the thing that bothers me about Glass Gem is the BS hype and misleading hucksterism that surrounded the GG craze. Starting with the backstory around Carl Barnes. I've got nothing against Carl Barnes, but the story was told as if he was a Cherokee amalgam of Obi-wan Kenobi and Luther Burbank. The emphasis on his native american heritage seemed deliberately over-hyped to try and sell the corn as if it was for all intents and purposes a sacred Cherokee heirloom instead of Carl Barnes' personal work product of his own intentional breeding program. The focus on his RACE vs his personal accomplishments as a plant breeder bugged me a lot. I guess any corn is cooler if you can say you got it from an Indian? To me its way more interesting that a guy in Eastern Oklahoma was breeding his own corn varieties, than that he was a Cherokee. Cherokee people are not particularly difficult to find in eastern Oklahoma, but amateur plant breeders are kind of rare everywhere. To top it off, most of this BS hype was begun and perpetuated by Native Seeds/SEARCH, including the rainbow photo that kept going viral and getting used on ebay etc. And NS/S was charging more for GG than all the other ACTUAL HEIRLOOM varieties they have collected. And they were putting people on a waiting list etc to amp up the viral furor, and then Bill McDorman got all bent out of shape that other people were selling it on ebay, when HE CREATED the whole artificial scarcity that made it possible. It was very disappointing to see one of my favorite seed companies behave so unethically (JMO). I also am just frustrated with the way people are only interested in pretty corn, vs all the other really interesting corns that are out there. Painted Mtn is a great corn, and an amazing bit of plant breeding work by one dedicated creator, but the reason its so popular is because there are lots of pretty ornamental colors in it. Being someone who raises two different grexes of corn that aren't visually dazzling like that (although I find them beautiful) but are being selected for nutritional/culinary quality, it rubs me the wrong way a bit that most folks just look at corn as a decorative object. And so I like to shit on GG when I think of it. |
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Post by walt on Feb 9, 2018 18:02:00 GMT -5
I knew Carl Barns. He seldom spoke of his Cherokee roots himself. Others did. He loved corn and collected all the kinds he could. He spoke of them constantly, which was good with me as I was learnibg much from him.
The history of each corn was important to him. History is much less important to people here. We are talking about food for today and tomorrow. But there's nothing wrong with others trying to preserve history. Of course preserving names and colors without preserving the vigor and adaption of a variety is not really preserving history. But it is no worse than people writing their limited version of history.
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Post by steev on Feb 9, 2018 20:12:56 GMT -5
I'm interested in my familial history, so knowledge of the crops they likely grew and the breeds of critters they kept and ate would add color and nuance to the story; I'd like to know where my Native American genes came from, let alone the Neanderthal genes. I'd like to know how I got here, in this hand-basket, and where I'm going.
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Post by steev on Feb 10, 2018 0:48:26 GMT -5
Day: While I realize your Papua/Iceland example contains no sickle-cell genes whatsoever, I get the concept; the thing about sickle-cell and thalassemia is that they give some protection from malaria, which is generally more fatal, though still a physical disadvantage, in areas where the benefit is not relevant. My understanding of the situation is that, while something genetic may be locally relatively advantageous, that doesn't make it a general advantage.
I think this is the whole point of landrace crops: that they work where they are, with minimal tech, chemicals, and fiddling.
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