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Post by Joseph Lofthouse on Dec 14, 2010 0:25:31 GMT -5
I have been sorting segregating kernels this week from my multi-colored sugary-enhanced sweet corn breeding program. My protocol for selecting the kernels is going something like this... Fill a jar about a third full of kernels, add water and shake well. Dump off any kernels that are floating. Repeat a few times until there are no more floaters. Let soak overnight (about 16 hours). Sort kernels into three classes... Hard or wrinkled kernels are discarded. Soft kernels that squirt when squeezed are discarded due to damaged hull. Soft kernels that are fully plumped are saved. Immediately dry the saved seeds in a dehydrator set at about 90F. [** See note added to bottom of post **] I taste a few kernels as I go along, and after I'm finished so that I can make sure that my selection criteria is working right. (The sugary enhanced kernels taste sweet and have a thin skin.) Any wrinkling at all in the kernel generally means it is not sugary enhanced. In some varieties, 100% of the kernels I have tasted after sorting are sugary enhanced. In other varieties it's harder to tell due to extreme diversity in the variety, but they are still coming in at around 95%. I could do this sorting just before planting in the spring, but I'm trying to minimize the spring rush. I'm being conservative in my selection criteria, so for example if a variety is expected to be 50% se+ I am only selecting about 40% of the kernels. I am also somewhat selecting for larger kernel size just cause I don't want to fuss with examining every tiny seed. It takes about 10 minutes to sort a thousand seeds. I have been really impressed this summer about what a great tool the human sense of taste is for selecting for sugary enhanced sweet corn. Here's what the seeds of one cross looks like: Spero's Red & Gold [(Shawnee Fire X se+) X se+] I believe these to be approximately 100% homozygous se. And the cobs they are coming from: The tip of most cobs is missing due to taste testing during the growing season. Ribbons were put around the cobs that were obviously high in sugar during the milk stage. Regards, Joseph [** Note added on 2011-01-11 Germination rate of the re-dehydrated seeds was around 30%, some varieties as low as 5%! I intend to run another set of tests. It's looking like this is best done just before planting. **]
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coppice
gardener
gardening curmudgeon
Posts: 149
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Post by coppice on Dec 14, 2010 10:22:27 GMT -5
Joseph, I'm curious have you made this sort of selection before? How well did re-dried seeds germinate?
I dunno if I'm bold enough to wake corn up (by hydrating) and try to put it back to sleep. Please post follow ups.
There is no criticsism implied here, just a "gosh, could this work" notion.
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Post by Joseph Lofthouse on Dec 14, 2010 12:42:26 GMT -5
I am being timid as well.... Saving plenty of unprocessed seed just in case something goes wrong.
The first time I tried this I got 100% germination in my kitchen. Better than I normally expect from corn seed. I attribute that to eliminating small and damaged kernels as part of the selection process... I'll do germination tests in a month or so. I haven't planted them into the field yet... [** Note added on 2011-01-11 Germination rate of the re-dehydrated seeds was around 30%, some varieties as low as 5%! I intend to run another set of tests. **]
Another technique I have been using is to screen cobs back-crossed to sugary enhanced corn by soaking 20 kernels in a shot glass overnight. The next day I can easily determine if the cob is 100% se+, 50% se+, or just an F1 hybrid waiting to segregate. Because only sugary enhanced pollen was used, this allows me to select some entire cobs without the soaking step.
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Post by johno on Dec 14, 2010 15:36:10 GMT -5
Are shot glasses legal in Utah?
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Post by Joseph Lofthouse on Dec 14, 2010 17:47:57 GMT -5
Are shot glasses legal in Utah? As long as they are used for sacramental wine (I mean sacramental water).
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Post by DarJones on Dec 14, 2010 22:29:25 GMT -5
The only negative I can see Joseph is that you are retaining only 25% of the genetics of the OP line. Said another way, 3/4 of the genetics come from commercial se+ highly inbred varieties. That is not necessarily bad, but it means more work to maintain diversity.
DarJones
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Post by Joseph Lofthouse on Dec 15, 2010 0:53:09 GMT -5
The only negative I can see Joseph is that you are retaining only 25% of the genetics of the OP line. Said another way, 3/4 of the genetics come from commercial se+ highly inbred varieties. That is not necessarily bad, but it means more work to maintain diversity. DarJones I agree completely... That always bothers me about back-crossing. The back-crossing was my way of taking a shortcut: To get an open pollinated 100% homozygous population going now. This population will have some Indian corn genetics in it but not as much as I would like long term. I have mostly eliminated the chloroplasts that came with the commercial se+ seed. (I kept some just for the principal of it.) If I knew a year ago how easy it is to select for sugary enhanced corn by the soaking method, I would not have done the back-cross, I would have used plain old segregation... I still have the F1 seed if I decide to try again. If I do more crosses or back-crosses, they will be done with my open pollinated sugary enhanced population so more and more Indian corn genes will accumulate in that over the years. The back-cross was beneficial in a few cases were corn that was represented as containing sugary enhanced genes had only a few percent, not the 50% that I might have expected based on the ad copy. At least next year it can segregate normally. A year ago, the only way I could envision selecting for sugary enhanced cobs was via statistical means... Destroying some amount of kernels in order to get a representative sample of the genetics of the cob. Now that I can easily select individual kernels without destroying them in the process things are much simpler. I figure that about 3000 corn plants participated in the breeding program this year either as mothers or as pollen donors. Many of them this year were flour, flint, or dent varieties, but as they segregate out they will add to the diversity. I figure that by the end of next year that several hundred families of corn (read that as varieties) will have been incorporated into my breeding program, although only about 60 of them will be represented in the homozygous se+ population by then. I sure am happy about plant breeding. Thanks all for your interest and helpful comments. And thanks for this forum in general that converted me from a company man to an honest farmer growing my own seed.
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Post by DarJones on Dec 16, 2010 2:17:50 GMT -5
One thought about narrowing the genetic base Joseph, since you backcrossed to se+, that means you have twice as many se+ seed to work with. As long as you maintain large populations, you can still get the desired result.
I would still suggest a further backcross to native varieties to improve the genetics.
DarJones
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Post by Joseph Lofthouse on Dec 16, 2010 11:46:42 GMT -5
I would still suggest a further backcross to native varieties to improve the genetics. I like that idea.... So far my strategy has been moving things closer to commercial sweet corn... I could just as easily be moving the se+ gene into Indian corn by doing the back-cross in the opposite direction. This year I made crosses of se+ to the following (native) varieties: Blue Hopi Taos Blue Pink Hopi Painted Mountain White Dent Red Dent Purple Flint Decorative Indian corn Peruvian Purple Flour Aztec Black sweet Nevada Black sweet Missouri Indian corn (Earth-tones dent) Anasazi And a few others that failed I'm guessing due to day-length issues. I intend to let them grow out and segregate without back-crossing. I'll be growing out that beautiful lavender dent corn from DarJones. I also made se+ crosses with these sweet corns: Painted Hills, LISP Ashworth su/se, (haven't processed it yet) LISP Festival su/se, (not as much se as I hoped) Astronomy Domine, (tiny amount of se found) Hooker's Triple Play, Sweet corn kernels found in Indian corn at farm stands. (no se found) And back-crosses which are providing my first (nearly) homozygous se seed. Inadvertent crosses from last year (Indian corn x Bodacious) and (Popcorn X Bodacious) Spero's Sparkler (Anasazi X se+), Red & Gold (Shawnee Fire X se+), and 51-A (Black Aztec X se+) I'll have enough seed to plant a huge patch this summer. Most of the diversity doesn't get incorporated until the summer after. And you know what I keep thinking? I really don't like how unreliable commercial se+ corn is for me in early spring... What if I do all this work and then I can't plant it until the middle of June? Maybe I'll decide that I prefer growing F1 hybrids in which only 25% of the kernels of the cob are expressing the sugary enhanced gene.
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Post by Joseph Lofthouse on Dec 16, 2010 12:01:00 GMT -5
Here's a photo of the variety that I am working on today: Spero's 51A (Black Aztec X se+) back-crossed to se+ sweet corns.
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Post by Hristo on Dec 16, 2010 13:21:41 GMT -5
What is your goal regarding sugar content? I see you mark the "obviously high in sugar during the milk stage" ones, but how sweet you like them? Here sweet corn was nearly unknown for the regular gardener 15+years ago and we ate dent corn until still tender. When I started to grow sweet corn I found that I do not like the really sweet ones, I'm just accustomed to less sweetness and more corny flavour.
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Post by Joseph Lofthouse on Dec 16, 2010 15:06:57 GMT -5
What is your goal regarding sugar content? I see you mark the "obviously high in sugar during the milk stage" ones, but how sweet you like them? Here sweet corn was nearly unknown for the regular gardener 15+years ago and we ate dent corn until still tender. When I started to grow sweet corn I found that I do not like the really sweet ones, I'm just accustomed to less sweetness and more corny flavour. My primary goal is to sell corn and/or seeds... The higher the sugar the better it sells. Multi-colored is healthier and has a marketing advantage at the farmer's market. Except early in the season, whoever gets corn to market first has a huge advantage regardless of how sweet it is. Traditional sweet corn is around 11% sugar in my garden. Ears with around 17% sugar are noticeably sweeter. Around 23% sugar it seems more like candy instead of corn... As a market grower, I have customers that like more corny and less sugar, and I have customers that like sugar, the more the better. I figure that the more sugar group is about 3/4. So I expect that I'll end up maintaining three populations... Main season corns around 11% sugar and 23% sugar. And a very early corn with low sugar since the sugary enhanced corn has not been reliable for me in early spring.
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Post by keen101 (Biolumo / Andrew B.) on Dec 16, 2010 15:13:46 GMT -5
What is your goal regarding sugar content? I see you mark the "obviously high in sugar during the milk stage" ones, but how sweet you like them? Here sweet corn was nearly unknown for the regular gardener 15+years ago and we ate dent corn until still tender. When I started to grow sweet corn I found that I do not like the really sweet ones, I'm just accustomed to less sweetness and more corny flavour. I too am curious to know what your overall goal is. That's probably one of the reasons i'm not particularly interested in growing out new sugar mutants myself. Most of the sweet corn already grown seems to have pretty good sweetness as they are. Once in a while i do taste one that is too sweet, and just irritates the taste buds on my tounge. Sweeter isn't always better, but i suppose it depends on what your aiming for. I do like the idea of crossing sweet corns with hardier ones to get something that grows in harsher conditions than most commercial varieties.
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Post by Hristo on Dec 16, 2010 15:19:45 GMT -5
I figure that the more sugar group is about 3/4. Interesting. I wonder if there is a significant difference of these stats between the people living in different states.
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Post by silverseeds on Dec 16, 2010 15:58:20 GMT -5
I figure that the more sugar group is about 3/4. Interesting. I wonder if there is a significant difference of these stats between the people living in different states. I find that interesting as well. I worked on a farm in ohio for many years, and also saw what joseph is saying in regards to the earliest corn, people only care that its corn. Possibly one of the corn experts here will chime in, but on our farm we grew what was one of the sweetest as of the mid to late 70s. when we grew the newer super sweets, very few liked them. Im not sure the percentages of sugar on those, but they sure werent the super sweet ones... Where I live now the sweet corn is very low on the sweetness factor, its all trucked in. So ANY fresh sweet corn would be a major improvement.
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