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Post by DarJones on Aug 6, 2010 0:46:28 GMT -5
I'm making a cross between Silver King which is a standard se+ variety and Cherokee Squaw which is a vigorous and healthy mid-flour/dent corn. The Cherokee Squaw will be the female parent. I am only growing about a dozen plants of each so it will be a limited genetic base. The Cherokee Squaw will be the female parent.
The corn is about 18 inches tall at present and is growing rapidly. I am watering it because of the extreme dry conditions in my garden. I have also fertilized it heavily.
The Cherokee Squaw seed I am using is from carefully selected ears grown in 2009 that exhibited long full ears with maximum row count and that had white cobs. The overall background of Cherokee Squaw is a mid to long season corn with very good shuck cover and medium height stalks. Production is high to very high for an open pollinated line. The kernel type is similar to a dent corn but it is softer. Kernel thickness is about 1/8 of an inch. The kernels were individually picked for bright creamy white color.
The breeding objective will be to isolate out an open pollinated line that is se+ within 2 generations and then to grow the OP line for several more generations to see if it can be stabilized. Primary selection criteria will be heavily biased in favor of plant health and vigor. Production will be evaluated on a per stalk basis rather than sib-line selection though that may change if there is evidence of an advantage to some lines vs others.
I will target a yield of homozygous se F2 seed in the range of 10 pounds. With a bit of luck, I will be planting the F1 seed next spring. It should take about 4 rows 120 feet long to produce this volume of seed.
Here are the selection criteria I am planning to use: 1. Plant Vigor 2. Ear weight and production 3. Kernel shape and characteristics 4. Shuck Cover 5. Cob color (white) 6. Flavor (yes, I will eat some to see how it tastes) 7. Stalk strength 8. Maturity date 9. Disease and pest tolerance
DarJones
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Post by grunt on Aug 6, 2010 1:30:11 GMT -5
Dar: Please keep us informed. I'm thinking of trying to do a bit of crossing here, with Painted Mountain as part of the base, but I'm not sure what I'll try crossing it with yet.
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Post by Joseph Lofthouse on Aug 6, 2010 5:22:48 GMT -5
Here are the selection criteria I am planning to use: 1. Plant Vigor 2. Ear weight and production 3. Kernel shape and characteristics 4. Shuck Cover 5. Cob color (white) 6. Flavor (yes, I will eat some to see how it tastes) 7. Stalk strength 8. Maturity date 9. Disease and pest tolerance How does selection for homozygous se fit into your selection criteria? How much of this list do you expect to give up in order to get se+? How are you planning to identify se+ kernels? and/or plants? (Or to eliminate those plants that are obviously not se+?) I am attempting to breed se+ sweet corn this summer. I sure have been disappointed with the se+ pollen donors. They sure seem like wimpy plants compared with some of the Indian corns I am crossing them with. Perhaps there is hope after all since the se crossed seeds that I got from J Spero sure are vigorous. Hopefully the poor vigor of the commercial se+ corns in my garden is due to being highly inbred, and is not a trait that is closely linked to the sugary enhanced gene. In my garden, if I ever am successful in getting a homozygous se+ sweet corn, one of the most important selection criteria will be that it must germinate readily in cold/wet/clay soil very early in the spring. I am so tired of my first few plantings of se+ corn not germinating first thing in the spring when normal sweet corn does fine. At least with my growing/selection protocol, I am not able to begin selecting for se+ until I grow out the F2 seed. (Which is not technically for me an F2 but an F1 back-crossed to se+) The back-cross is the only way I can envision to eliminate that pesky gene that would lead to a few percent of normal sweet corn showing up in my population every year. I almost failed with my first planting because my Painted Mountain corn came up fast and vigorous in early spring and the 65 day se+ corn I planted the same day didn't germinate well, so by the time the Painted Mountain was silking I didn't have a pollen source. Fortunately the painted mountain was still receptive to pollination when the second planting of se+ started shedding pollen, so I was able to gather pollen from another part of the garden and carry it to the plants. Regards, Joseph
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Post by Joseph Lofthouse on Aug 6, 2010 11:54:36 GMT -5
I will target a yield of homozygous se F2 seed in the range of 10 pounds. With a bit of luck, I will be planting the F1 seed next spring. It should take about 4 rows 120 feet long to produce this volume of seed. In my garden, growing commercial seed, 10 pounds of dried down sugary enhanced corn seed can be produced in about 50 row-feet. [1/10th pound seed per cob, with 2 cobs per plant, and plants 1 foot apart.] Regards, Joseph
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Post by DarJones on Aug 6, 2010 16:10:35 GMT -5
That works if you are growing pure seed but if you are only expecting 1 seed in 4 to be pure homozygous se, then you have to grow at least 4 times as much. Note that I will be planting the F1 seed next spring presuming I manage to get a fall crop from the plants growing now.
DarJones
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Post by canadamike on Aug 6, 2010 17:39:15 GMT -5
Dan: one of the main problems of indian flour corns is lodging. I sure can tell you Painted Mountain is not a very robust plant. Grin has a few selections created in Canada, CG Stiff Stalks....(whatever the number or rest of the name). There is also Meskakie ( if I spell it right), available through our friend George in the SSE catalogue. It is a dent that resistent 70mph winds, with a huge root system. Ican tell you one thing, if we come up with a stiff stalked native flour corn, a lot of dairy farmers in North America will love us. And it is not because it is unachievable, it is simply because the industry is revolving around VERYT VERY average corns, it pays much more to feed 5 kilos of corn per day of an average corn than 3 of a good flour corn.
I have gone through almost all that is available to dairy farmers, even in the organic corn industry. I met and talked to breeders too. And while the farmers request more soft starch, you talk to the guys telling them flour corns DO EXIST and they look at you as if you were an alien...
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Post by darwinslair on Aug 6, 2010 18:23:23 GMT -5
Huh. Now Painted Mountain is one of them that has NOT been a lodging problem, and I have it planted in the wide open with no protection at all.
Worst is Mandan White Flint. But picked itself up. I think it was meant to be hilled up as it grew.
Tom
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Post by Joseph Lofthouse on Aug 6, 2010 22:25:12 GMT -5
That works if you are growing pure seed but if you are only expecting 1 seed in 4 to be pure homozygous se, then you have to grow at least 4 times as much. Note that I will be planting the F1 seed next spring presuming I manage to get a fall crop from the plants growing now. DarJones Since the sugary enhanced gene and the sweet gene are on separate chromosomes, I only expect 1 kernel in 16 of the F2 to be both sweet and homozygous for sugary enhanced. Regards, Joseph
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Post by Alan on Aug 6, 2010 23:09:09 GMT -5
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Post by atash on Aug 6, 2010 23:26:55 GMT -5
Interesting discussion. I learned something today.
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Post by DarJones on Aug 7, 2010 10:04:44 GMT -5
Nice article Alan. It goes a long way toward explaining why I need about 10 pounds of seed to work with. Joseph, I hope to take advantage of a trait influenced by the se gene that has not been widely documented. It has nothing to do with color or with sugar content and it is only expressed in the homozygous state. If I am correct - and tests made this past season look promising - then I will be able to identify homozygous se plants when the seed germinate. To get a population of se+ plants out of the F1 cross, 1 in 4 seed should indicate a normal sugary expression after the seed dry. I will sort out the seed that have that phenotype. That should give me a large volume of seed of which 1/4 should be se+. I will then start about 1000 seed in cell trays and evaluate them for this trait. www.globalsciencebooks.info/JournalsSup/images/0706/IJPB_1%281%2927-30o.pdfDarJones
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Post by Joseph Lofthouse on Aug 7, 2010 11:52:41 GMT -5
If I am correct - and tests made this past season look promising - then I will be able to identify homozygous se plants when the seed germinate. That would be really clever! Can you share the technique? Regards, Joseph
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Post by DarJones on Aug 7, 2010 19:25:31 GMT -5
Joseph, The pericarp of (su/su se/se) seed is very thin compared to any other combination. Look it up in the literature and you will find only brief mention of this effect. You cannot tell when the seed are dry, but after they germinate.......
DarJones
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Post by Joseph Lofthouse on Aug 7, 2010 20:06:09 GMT -5
Joseph, The pericarp of (su/su se/se) seed is very thin compared to any other combination. Look it up in the literature and you will find only brief mention of this effect. You cannot tell when the seed are dry, but after they germinate....... DarJones That would be a tremendous boost in our ability to select for se+ sweet corns. Thanks! I'll start reading and sprouting corn. Regards, Joseph
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Post by grunt on Aug 7, 2010 22:01:18 GMT -5
You probably have this site marked already. I stumbled on it trying to find info on pericarp thickness = www.maizegdb.org/ Database goes back to 1932.
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