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Post by reed on Nov 20, 2014 7:41:45 GMT -5
Carol Deppe, blueadzuki, Regarding your prior discussion on sweet corn crossing on flour you mention ending up with kernels that are basically empty shells. Is this because the sugar mutation (inhibiting the conversion of sugar to starch) is more pronounced on a flour kernel? Is soft flour endosperm more susceptible to this than hard flinty endosperm?
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Post by reed on Nov 20, 2014 7:57:25 GMT -5
Another question(s), I have noticed when I pick corn in milk stage I often notice white kernels and yellow kernels on the same ear. Actually multiple shades of yellow, probably too subtle to notice if they were not right beside each other.
I'm thinking that might be indicative of endosperm color not yet obscured by aleurone or pericarp. Is that correct, that the endosperm can have color early on and that the other colors develop later?
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Post by Joseph Lofthouse on Nov 20, 2014 8:49:08 GMT -5
There is a lot of diversity within corn... I have been selecting my version of Astronomy Domine sweet corn for bright colors in the kernels in the early milk stage. When I first started growing it, many of those colors didn't show up until dough stage. There are some pericarp colors that get dark long before milk stage. Here's an example in the early milk stage. The purples, blues, and reds are just starting to develop and obscure the endosperm color. If I had waited a couple more days to pick they would have been much darker.  |
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Post by Walk on Nov 20, 2014 10:29:14 GMT -5
Walk, I love happy accidents! Have you tried the dry sweet corn any other way? We sometimes grind the mature dry sweet corn for meal and add it to multi-grain pancakes or cornbread in small amounts. It is quite sticky but the flavor is very nice. Mostly our sweet corn is put up as dehydrated in the sweet or green stage. We blanch and cut off the kernels and put it in the solar dryer for a couple of days. When rehydrated it's a bit like canned corn and is good on it's own or added to other dishes. |
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Post by blueadzuki on Nov 20, 2014 10:44:04 GMT -5
Carol understands the empty kernel thing better than I do, but as far as I can tell it boils down to the sugary mutation doing different things to the different starches. Hard starch gets blocked from converting and so it stays sugary. Soft starch is more or less eliminated. So if you have a floury corn, which is pretty much ALL soft starch you win up with a kernel with the skin (aleurone and pericarp) the germ, and nothing else.
While Carol never said this explicitly I suppose it also means that a sweetcorn derived from a flint corn will have bigger, fatter kernels than one derived from a dent of comparable kernel size, since there is less "stuff" removed. I also imagine that that would mean that the mutation in a glassy flint would yield EXCELLENT sweetcorn, since it's pretty much ALL hard starch
As for the color thing, you are right. The endosperm basically colors up as it forms, the aleurone and pericarp color up later. That's probably one of the reasons there are comparatively few "true" heirloom (as defined as a strain that is actually old, as opposed to a recent creation done by heirloom type methods) colored sweetcorns. By the time they had colored up they had usually passed the point where they were still good to eat as corn on the cob. To get that kind of result, you have to actively select for corns that color up early like Joseph is.
The shades of yellow are due in part to the endosperm being triploid (3n as opposed to 2n) The endosperm has two major color traits Yellow (Y) and white (y). The more Y you have, the stronger the color. In a full on maximum cross where both parents are heterozygous for Y you can get four basic outcomes, white (yyy) light Yellow (Yyy) medium yellow (YYy) and dark yellow (YYY). And of course there are other genes that can modify all of this (like the one that ups the carotene content and makes the yellow more like orange)
In my experience, most ornamental corns are hetero for Y. I imagine they do that on purpose, mixing white based and yellow based corns and letting them cross with each other. If you goal is as colorful a cob as you can get, it makes sense to do this; make the corn hetero for yellow, and you've basically quadrupled the number of possible kernel colors you can get.
While I don't know this for certain I would also imagine that, if you have a corn that has the (somewhat scarcer) genes that actually allow for colored endosperm and it gets sweetcorn DNA you wind up with a corn that colors really early and really deep.
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Post by Joseph Lofthouse on Nov 20, 2014 12:14:08 GMT -5
Here's what a sweet corn looks like that has been partially pollinated by a flour corn:  And a dissection of a couple of the kernels. Flour-pollinated on the left. Sweet on the right. For what it's worth, the flour kernel weighed 230 mg and the sweet kernel weighed 140 mg.  I have found that during segregation in succeeding generations, the sweet type reverts to it's archetype regardless of whether one of the ancestors was a flour corn, or a dent, or a flint. That might just be me... Selecting for the sweet corn archetype that my family/society brainwashed me into believing. Carol: It's a joy to have you here. The idea that "There is only breeding" is a powerful thought to me. It gets to the heart of why I distrust the heirloom preservation movement so much... Nothing is static. Growing a variety is changing it in some way or other even if we don't see the change. |
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Post by Walk on Nov 20, 2014 15:54:48 GMT -5
Carol, I too loved what you said "There is only breeding." I don't think the majority of seed savers realize the potential power they are exercising when they make even basic selections. I was corresponding with someone the other day about how to thresh sorghum. The person was left with about 10% of kernels that weren't threshing free of their glumes. I told her that she had several options to deal with this, one of which was to use these seeds for planting stock instead of cleaning sufficiently for eating. But I warned her that this approach could inadvertently be selecting for sorghum that doesn't thresh easily. One of the dumb seed saving decisions I made early on was to select Ponca Butternuts for extra large necks and very small seed cavities. Eventually the variety didn't make seed and it was a dead end, the result of my pursuit of a narrow focus on yield over the plant's ability to reproduce successfully. Perhaps that's why I now like weedy/seedy crops more than I might have in the past.
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Post by reed on Nov 21, 2014 4:30:30 GMT -5
The first ear in Joseph's AD photo is what I'm used to seeing but with different shades of the yellow. If I wait till the slightest hint of another color ( or even if any yellows get too dark) it isn't good for corn on the cob any more. Joseph's photo of AD is an actual sweet corn though so that explains that. I wish I had known about AD before I bought all those other sweet corns but o'well. If I decide in the end not to abandon the sweet corn part of my project I may try to get some AD to add in, I mean why try to reinvent the wheel.
Knowing that the endosperm color can be determined at this stage I'm wondering if one could pull down the shucks and tag kernels somehow and then know which was which later on. That would be very useful for segregation in something like "Big Red".
The picture of the sweet ear with some flour pollinated kernels is also very instructive and is what I pictured in my imagination it might look like. Easy just to leave the plump ones out of the next years seed and it sounds like it has a tendency to pretty easily revert back to sweet anyway. I also bet for corn on the cob a few flour cross kernels wouldn't even be noticeable. Especially to someone like me who likes a good amount of corn with their sugar.
That might solve the problem of growing two kinds right together from the sweet end of the patch but what about from the other end? Are there other issues that make it more complicated from the other end?
One I'm thinking of is that if crossing occurs you could end up with a normal looking flour / flint kernel that still had the sweet gene hiding inside. You could easily pluck out the sweet looking ones but others with the sweet gene might still be there. I also have this notion in the back of my brain that since I'm not really after an absolutely pure flour this issue could be different than for someone who is.
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Post by Joseph Lofthouse on Nov 21, 2014 12:46:07 GMT -5
The ear on the far left is Ambrosia se+ commercial sweet corn. It was grown by my daddy. I often mark corn kernels, while still on the plant with a sharpie marker... It's hard to see the marks on dark colored kernels. Perhaps there is a suitable paint pen. A little bit of sweet genes running around in a flour corn would be acceptable to me. I see it frequently in decorative corns at the grocery store. I wouldn't pick out the kernels before cooking. A little bit of off-type isn't going to affect the culinary traits enough to worry about. However, if I ever see sweet kernels on a flour or pop corn, I use that cob for food but don't save seeds from it. I know that half of the kernels on that cob carry a recessive sweet corn gene. Sure it shed some pollen, but not saving seeds from cobs that show recessive sweet traits pushes the population hard towards the flour/flint side of things. You can do other things to keep them more separate: Isolation by time, or by distance. In my garden, most corn pollen falls mostly straight down most of the time. We didn't find any Astronomy Domine pollen that did it's thing in my daddy's ambrosia patch. They were flowering at the same time and separated by about 100 feet. Even in a 10 MPH wind, corn pollen only travels about 25 feet. I grow small patches of what I call semi-isolated corn so that I can concentrate the various colors. I get around 5% or less crossing between them when separated by 11 feet. Can you hear the drum beats? The marketing departments of the mega-seed giants? Telling you how critical isolation is? And how vital to your survival that you only grow pure seed? Besides impurity is a sin? And pollen is traveling from Africa to infect your corn? And from Iowa? Worry about uniformity is important when crops are being harvested and processed by machine. It is important when a few percent of off-types can make a difference between profit or loss for a business. I think that uniformity is detrimental to small scale growers who do the work by hand. The truth about pollination is that when plotted on a bell curve that it is an extremely local event. And while pollen might travel from Iowa, for every grain of pollen that makes the trip, there are trillions of pollen grains being generated locally. Here's what that looks like mathematically for a couple of carrot patches separated by about 10 feet. Sure there is a little bit of cross-pollination going on. Does a home-grower care about that? I wouldn't.  I might however worry about having a weed growing inside my patch. For example one QAL plant growing in a row of carrots. The bell curve for that event looks like this:  I made this graph 2 dimensional... I got D grades in the advanced mathematics classes that I was required to take in college. A true 3D graph would show less contribution from the weed. When I find sweet kernels on a decorative cob at the grocery store it is typically around 2% that are sweet. |
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Post by Carol Deppe on Nov 21, 2014 18:30:14 GMT -5
Carol Deppe, blueadzuki, Regarding your prior discussion on sweet corn crossing on flour you mention ending up with kernels that are basically empty shells. Is this because the sugar mutation (inhibiting the conversion of sugar to starch) is more pronounced on a flour kernel? Is soft flour endosperm more susceptible to this than hard flinty endosperm? It seems to me that su eliminates most, in some cases even all of the floury endosperm from the mature kernel while having little or no effect on the amount of flinty endosperm. In the F2 of crosses between pure floury varieties and sweet corn you usually get segregtion for different degrees of dentiness and and endosperm amounts, with some of the sweet kernels having very little endosperm at all. In crosses between flint varieties and sweet, in the F2 you see segregation for sweet and for endosperm type from more dentish to more flintish. And you don't see empty kernels. |
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Post by Carol Deppe on Nov 21, 2014 18:41:25 GMT -5
Carol understands the empty kernel thing better than I do, but as far as I can tell it boils down to the sugary mutation doing different things to the different starches. Hard starch gets blocked from converting and so it stays sugary. Soft starch is more or less eliminated. So if you have a floury corn, which is pretty much ALL soft starch you win up with a kernel with the skin (aleurone and pericarp) the germ, and nothing else. While Carol never said this explicitly I suppose it also means that a sweetcorn derived from a flint corn will have bigger, fatter kernels than one derived from a dent of comparable kernel size, since there is less "stuff" removed. I also imagine that that would mean that the mutation in a glassy flint would yield EXCELLENT sweetcorn, since it's pretty much ALL hard starch In sweet corn, the conversion of sugar to hard starch is delayed, but apparently not actually blocked, because you end up with a kernel that has plenty of hard starch. And yes, you can get very fat sassy looking sweet kernels when sweet genes contaminate a flint variety. I'm speculating that a sweet corn variety that was a purer flint background (instead of the more typical dent background) might potentially have more vigorous germination and early growth and maybe better cold germination than most (dent-background) sweet corns. So I've tried more than once to breed from sweet contamination in flint varieties. To no avail. Usually there are multiple different genes for sweet in there (not just su but also sh), so I when I just pick out the sweet kernels and plant them in a patch, I get a mix of sweet and field, not pure sweet. I'm enough interested in the potential of a sweet with a pure flint background that this year I'm planning to make some deliberate crosses of flint corn and sweet corn and go from there and see what happens. |
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Post by Carol Deppe on Nov 21, 2014 19:10:08 GMT -5
Carol, I too loved what you said "There is only breeding." I don't think the majority of seed savers realize the potential power they are exercising when they make even basic selections. I was corresponding with someone the other day about how to thresh sorghum. The person was left with about 10% of kernels that weren't threshing free of their glumes. I told her that she had several options to deal with this, one of which was to use these seeds for planting stock instead of cleaning sufficiently for eating. But I warned her that this approach could inadvertently be selecting for sorghum that doesn't thresh easily. One of the dumb seed saving decisions I made early on was to select Ponca Butternuts for extra large necks and very small seed cavities. Eventually the variety didn't make seed and it was a dead end, the result of my pursuit of a narrow focus on yield over the plant's ability to reproduce successfully. Perhaps that's why I now like weedy/seedy crops more than I might have in the past. Exactly. The essential genetic method involved in seed saving is selection, and selection is actually much more complex than people often realize. For example, if I have a room full of ears of corn and choose the biggest for seed, I may actually be selecting for lateness. Often it's the later, bigger plant that produced those biggest ears. If you transplant a variety that has big vigorous roots, you not only are no longer selecting for ability to germinate and grow outdoors in real soil and weather, but you may also be selecting for slower germination or wimpy root systems. (The fast germinating seeds with big root systems are more likely to overgrow the pot or have their roots damaged in transplanting.) My corn, beans, and squash varieties are always direct seeded, and they germinate fast and have extremely aggressive roots. It's quite possible if you transplant that a variety that puts out a more restrained root system might be better for you. Full bush squash varieties normally don't even survive under my growing conditions because they have restricted bush root systems that don't get down to moist soil fast enough to survive on my regime of little or no watering in spring. But such varieties would undoubtedly have root systems more amenable to being potted and transplanted. I think a concept of whether the variety is to be direct seeded or transplanted needs to be a basic part of the definition of the variety. (All my corn, beans, and squash are designed for direct seeding.) If you do your thinning of corn or peas or beans before the plants are about 4 inches or so high, you are actually not selecting the best most vigorous genomes. I've seen plenty of chlorophylless mutants. The plants are yellow. They grow to 2" high just as fast as the rest. Then they come to an abrupt halt and cease all growth and die. This tells me that big-seeded varieties have enough food and biochemistry established by the mother that their own genes don't express enough to affect their performance until they are pretty big. So to select for vigor and rapid growth, I let the plants get to at least 4" high so they have had a while to show what they can do based upon their own genes. Only then do I thin. In that way I get powerful selection for vigor and growth rate just by thinning, which has to be done anyway. But it's all in exactly when and how you thin. I think the reason most squash varieties deteriorate so rapidly once the breeder releases them to the commercial trade is that the seed is collected by big machines rolling through the field. The fruits with big seed cavities (meaning thin flesh) are the ones with more seed. So commercial squash seed production selects for thin flesh, big seed cavities, and lots of seed. Likewise, more smaller seeds are selected for over fewer big seeds. If you save seed from all your squash without deliberately evaluating each fruit for flesh thickness, you too can select for thin flesh, large seed cavities, and small seed. :-) |
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Post by Carol Deppe on Nov 21, 2014 19:40:57 GMT -5
The truth about pollination is that when plotted on a bell curve that it is an extremely local event. Joseph, you seem to have unusually little wind. At least during whatever part of the day and year your corn is releasing pollen. How local pollination is or isn't undoubtedly varies widely depending upon just whose corn patch and region we are talking about. Pollen release of my early corns is usually about 11 am or so. (In hotter drier places it is much earlier.) By then we always have a good stiff breeze whipping through. (I really notice because it interferes with garden photography.) If I pour out some threshed beans at this time, the chaff is carried an obvious 30 feet or more. When people till at that time of day on ground that is dry, the cloud of dust billows out for hundreds of feet (their topsoil blowing away). Corn pollen is much lighter than most of that visible dust or bean chaff. So, not surprisingly, pollination isn't so local in my corn patches. For example, when we planted an early white flint and a late yellow sweet, the pollination windows overlapped just a little. Yet this was enough so that even though we ate the four rows of flint closest to the sweet, the next four rows or so also had lots of contamination (multiple kernels on every ear). (We harvested them separately.) There were also occasional other contaminants on the rest of the ears. Enough so that had I not had screened them out, my 'Cascade Creamcap' flint would have taken a huge step backward toward mixed endosperm color instead of being pure for white. Pure white has a neutral flavor that is great with fine cheese, fish, smoked salmon, and for sandwich bread. Yellow corn tastes more like commercial corn, an OK flavor, but it doesn't go with everything. So a mixed endosperm type might be ok with some people, but I bred Cascade Creamcap for the particular flavor of white flint corn, and do not want the yellow in there. |
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Post by Joseph Lofthouse on Nov 21, 2014 19:58:58 GMT -5
A recent inadvertent selection that I became aware of in my garden was for tomatoes with an "arching vine" arrangement. I call it that because the tomato vine forms an arch that holds the fruit above the ground. I grow my tomatoes sprawling, and I don't like to save seed from rotting fruits, so I have been inadvertently selecting for plants that hold the tomatoes out of the mud. (Also I expect that I'm selecting for thicker skin.) I became aware of this trait when I trialled a bunch of new varieties, and they sat heavy on the ground and rotted much more than I was used to.
I keep doing "direct seeded tomato" experiments, but haven't been successful yet. It's been a low priority project, but something I put a little bit of effort into most years.
To avoid the issue with "prolifically seedy" plants taking over the population, I plant some things fruit-to-row. If I also harvest per-row, then I can evaluate for productivity and/or other traits that are important to me.
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Post by Joseph Lofthouse on Nov 21, 2014 20:03:52 GMT -5
In thinking about wind... I have very little during the summer. I sprinkle irrigate, and only remember a couple of times in the last few years when the wind was blowing hard enough to interfere with irrigation. We get thunderstorms once in a while, but they come and go in an hour or so. There definitely isn't a prevailing wind that makes the trees grow side-ways. I give very little thought to selecting against lodging in any crop.
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