understanding corn genetics

[Deleted]

Joseph,
Most modern hybrids' genes are sourced chiefly from the eastern USA, aren't they? It's no wonder then that they do poorly in the mountainous West, given how different the environment is there. Also, is it true that 43% of the USA's corn acreage is derived from 6 inbred lines? That seems like a recipe for another 1970 to me.

[DarJones]

I'm not the person with the experience to give a really good answer re your question of developing a synthetic corn race. I can say that if you put enough time and effort into it you should be able to develop significantly better production potential than many hybrids. From your description, that could take 20 to 30 years. Please read the history of Reid's Yellow Dent for a better understanding of the requirements involved. One of the early problems I foresee is that you will have a huge number of deleterious genes to weed out. This is because the 4 racial groups mentioned are adapted to widely divergent climates.

DarJones

[Joseph Lofthouse]

A study I'll link to later on found that the sweet corn they looked at is 72% derived from the Northern Flint race.

I have a number of social and climatic issues that interfere with my ability to get good results growing highly inbred commercial hybrids.

• I won't apply poisons to my seeds or garden, so inbreds that have been selected to depend on poison to germinate or grow do not do well for me. [Yes I think that could very well be another dirty seed company secret plan to make farmer's dependent.]
  
• I don't apply commercial fertilizers which puts the inbreds at further disadvantage.
  
• I don't currently have a genetically diverse open pollinated homozygous se+ sweet corn. So I am comparing the reliability and adaptability of an open pollinated line to the fickleness of highly inbred lines. The inbreeds are at a severe disadvantage.
  
• My climate and altitude is radically different from Iowa's.
  

Nov 9, 2011 0:28:49 GMT -5 DarJones said:

the 4 racial groups mentioned are adapted to widely divergent climates.
DarJones

Based on the phylogenetic tree of Zea Mays, the race most likely to contribute significant advantage to a breeding program is the Tropical Highlands race.
www.genetics.org/content/165/4/2117.full.pdf
This is also the most difficult for northern temperate growers to deal with.

[Deleted]

"One of the early problems I foresee is that you will have a huge number of deleterious genes to weed out."
DarJones

Yeah, the article I posted earlier talked about that: supposedly, 52% of the plants from the F2 generation of a Virginia Gourdseed X Longfellow cross either produced hardly any seed or were totally barren. I suspect the number would be even higher if, say, an Abenaki were bred to a Cuzco Gigante (both strains I plan to use). With the way I'm trying to pair up the varieties now, the differences will (hopefully) be fairly incremental rather than night and day so that I can avoid some of the combining problems as I progress toward the final product. I know the project will take a long time, but the feeling of satisfaction and possibility of making something that can help other people is more than incentive enough to go for it.

[12540dumont]

Dar/Joseph/Corny guys,
Now that all the corns are out of the field, dried, shelled and jarred up for storage, I can get on with all my corny questions.

One of the Italian corns that I planted, which has really great flavor had an abysmal yield. It yielded only half of the amount of the Texas Gourdseed and only about 1/4 as much as the Cascade Creamcap.

So, how could I go about increasing the yield of this variety?

Also, in Carol's book she talks about gently folding corn varieties together. I'm familiar with folding and do a mean t-shirt and tea towels, but I have no idea what she is talking about.

I do love that Texas Gourdseed and may have to grow it again just because I so love that flavor. It makes awesome bread.

[DarJones]

Seriously? You mean you never folded corn? What on earth do they teach in home ec these days.

There is no "gentle" way of folding varieties together. What you would do is find a highly similar variety and cross your low producing corn with it in hopes of improving the overall production. Presume you are using a variety like Floriani Red Flint polenta corn. Select a complementary variety like Abenaki flint to cross it with.

Floriani is a red corn with slight white caps, conic seed form, slight conic ear form, which means is could very well be derived from the Conica race group.

Abenaki is a mix of yellow and red kernels that are oval flint and very early maturity. You would select the red kernels to cross with the Floriani.

The traits you would like to combine include the high cooking quality of the Floriani with improved vigor and early maturity from Abenaki.

Start by making a small cross involving 20 or 30 plants of each variety for example planting the Floriani 2 weeks before the Abenaki to account for the difference in maturity. When the corn starts to tassel, pull out all the Floriani tassels. This will force a cross with the Abenaki pollen which is all that will be available. Save the seed from this cross and plant it the next year but this time, plant 200 to 400 Floriani plants and at least 100 of the Floriani X Abenaki. Again detassel the Floriani and let the hybrid plants produce all of the available pollen.

At this point, you have produced a hybrid and backcrossed it so the concentration of Floriani genes is 75% of the population. Grow the corn for 6 more generations and each time select for the traits you want to emphasize. You should get segregation for earliness, productivity, and eating quality.

DarJones

[canadamike]

I share your frustration.

I am working my ass off to make OP corn more mainstream. But alas, we have to be frank, it is usually poorer in total yield, if yeild means weight.

But it is often higher in yield in terms of proteins per acre, at least for the selections made for today's for productivity.

When you deal with heirlooms, PLEASE forget productivity and concentrate on nutrition and taste.

Old corn will ALWAYS TASTE BETTER AND BE MORE NUTRITIOUS, but less productive.


We are working hard to bring old genetics to modern standard of productivity, it is now achieved with sileage corn, basically animal feed, because there is almost as much protein in the stalks than in the ears. But we are not here yet, almost there but not here, standability being where it all hurts first...then yield, but this one would be improved by much better standability.

The natives were wise when growing the 3 sisters, the beans kept the plants together in a tangled mess of some sort.

But today only 3% of the people are growing the food of the others, and the 3 sisters are not much of an option.

It pisses me off...this is a true case of getting the truely best food in a smaller system built on self reliance.

We are working hard to bring OP corn to modernish ( kind of) standards of production. Production does not means productivity in a commercial way... non ecological..it means productivity within a biological system that is alive...we bet it will beat chemical growing..we might be dreamers, but it has been done with sileage corn, we have a victory here, and more work to do...

[Joseph Lofthouse]

Nov 21, 2011 22:13:12 GMT -5 canadamike said:

The natives were wise when growing the 3 sisters, the beans kept the plants together in a tangled mess of some sort.

The first year I grew turnips for seed, they fell over, popping the roots out of the ground and killing many plants.

Most recently when I grew turnips for seed, I wrapped the stems around each other early in the season so they were all a tangled mess of some sort. They stayed upright and in the ground until harvested.

[12540dumont]

This was a corn called Nostrano Agostinello. It's a gorgeous orange color that when ground and cooked is brown.

It made the best grits! With a fried egg on top...mmm.

But the corn only made central corns, no side shoots and mostly only one corn per stalk. Very very few doubles. I planted this on July 1 and harvested it on Oct 22.

I dunno, I had home-ec in 1970. We made bread and t-shirts. Corn was never mentioned.

I suppose I should grow it again to get a big population before I start fooling around with it. Thanks, Holly

Attachments:

[Deleted]

Okay, I've finally gotten ahold of the tropical varieties I was interested in, and I have my composite's pedigree figured out. Here it is. (Please feel free to critique.)
Group 1:
Double Red Sweet
Gigi Hill
Painted Mountain (50%)
Rhode Island White Cap
Roy's Calais

Group 2:
Mayo Tuxpeno
Pepitillo
Tohono O'odham June
Virginia White Gourdseed

Group 3:
Aztec Red
Aztec White Giant
Cherokee White Flour
Jala

Group 4:
Cuzco Gigante
Hickory King (50%)
Maiz Morado (Cuzco Morado, I believe)

Group 1 is all Northern germplasm and are around 7-8 feet, 8-12 inch ears, 8-10 rows (except Double Red), and 105 or fewer days to maturity. The Double Red is for anthocyanins only, and the sweet gene will be bred out. Group 2 is entirely Southern dent / Northern Mexican, at around 10-14 feet, 7-10 inch ears, 12-18 rows, and 130-140 days. Group 3 is the most heterogeneous, but the Jala and Cherokee White should pair up reasonably well in terms of height and ear characteristics, and the shorter Aztec Red & White should moderate the height down to a more manageable 12 feet or so and thicken up the other 2's thin ears. Group 4 is all 12-16 feet, 6-8 inch ears, 8-10 rowed, big kernelled, and late (130-150 days, I think). I'll have to do a couple cycles of tropical backcrossing in it to recover the Andean genes.
Groups 1 and 2 will be crossed and selected for flinty kernels, anthocyanins, strong 10-12 ft stalks, lower row numbers (10-12), and longer ears (9-12 inches). Groups 3 & 4 will be crossed and selected for long ears (14-16 inches from the Jala), lower row number (10-12), stout 12-14 ft stalks, big kernels, and anthocyanins (from the Morado). The final two strains will be bred together and selected for all the traits of the groups 3 & 4 cross plus flinty kernels. I'd like a maturity date at around 140-150 days (our growing season is fairly long) for maximum productivity. I figure at least a good 30 years to the final product, but I'll be growing corn each year anyway, so why not make something new at the same time?

[oxbowfarm]

Once you start getting the groups selected for what you want I hope you will share them with other folks. You might find something valuable long before your endpoint. Plus it would preserve your work at other locations in case something happened to you and you couldn't complete the project yourself, a lot can happen in thirty years.

[Deleted]

I'd be more than willing to give out seed from my crosses if they're worth anything at all. Thankfully, some of them have already been done before, so I know they should work (Northern Flint x Southern Dent for cornbelt dent & Tabloncillo x Cuzco for Pardo). And you're absolutely right: 30 years is a mighty long time. Come to think of it, I'll be 50 by then! Man...

[Joseph Lofthouse]

I'm very disorganized about plant breeding... It's just too hard to predict ahead of time what is going to do well in my garden, so I might as well start with planned chaos. That way I'm not disappointed when chaos arrives.

I can't trust descriptions about plants that I find on the Internet. I can't trust that the varieties sent to me are the varieties I ordered. There is just too much chaos especially when dealing with rare and/or heirloom varieties.

After 2 years of trying I still haven't got a cross between a tropical highlands corn from Oaxaca and a northern sweet corn. Maybe next year will be a charm and maybe it won't. I didn't even get an increase of seed this year.

If this were my project: To make a semi-formal synthetic composite between unpredictable and unknown corns, I'd do it as: a couple years worth of modified hybrid swarm crossing followed by some years of mass selection.

The first year I would plant equal numbers of seed of each type as a variety-to-hill (5 to 7 seeds) planting, and replant any kernels that didn't germinate. I would stagger the planting times so that there was a good chance of the early varieties and the late varieties cross pollinating. (I'd do this both by replanting seeds that didn't germinate, and by extending the length of each variety's row or adding another seed to it's hill.) I would detassel half the varieties and then I'd save seeds only from the detasseled plants. This would ensure that every saved seed is a hybrid cross. (Except for the kernels that get self pollinated by a sneaky chaos-inducing tassel.)

I would only save one cob from each mother plant, and I would combine equal numbers of kernels from each cob, into a blended mix for each mother variety. This would insure that a plants genes don't get over-represented early in the project just because it produces more cobs, or more seeds per cob.

I'd grow two patches separated by perhaps a hundred feet. In the second patch, I'd detassel the varieties that are the pollen donors for the other patch. This would insure that every variety's cytoplasm is carried through to next year.

The second year would be a repeat of the first year, except that I'd mix up the planting order, and I'd plant a larger number of seeds as a variety-to-row planting (10 to 30 seeds per variety).

The third year I would plant equal numbers of seeds from each variety randomly jumbled up into the field with random planting times. I would let them openly cross pollinate. This year I would start selecting for corns that meet my desired phenotype by saving one cob from about 25% of the plants that are approaching my ideal. I'd save the seed as ear-to-packet, and plant it as ear-to-row or modified-ear-to-row the following year.

Then a few more years of modified-ear-to-row selection and I'd be content with my great new variety.

That's the ideal, but with my luck, some varieties are not going to grow in my garden. Some may be incompatible with others. Some will be lost due to bugs, or weather, or pigs, or voles, or all-terrain-vehicles. So I'd muddle through.

In practice though, I don't set out to make synthetic composites... I am content to add diversity to my current landraces by hybridization followed as needed by segregation. For example: I am adding diversity to my open pollinated sugary enhanced sweet corn in the following manner. 1- make a cross between a southern dent and a sugary enhanced sweet corn. 2- plant the F1 seed and allow it to segregate. 3- Select kernels of the desired phenotype. 4- grow them out one year and if phenotype is acceptable add to my main population.

In general, whenever I add a new variety to my landrace corn, I do so by trialing the new variety as a detasseled mother plant inside the main patch. That way if it grows acceptably, it's children are kin to my existing landrace. If it doesn't grow acceptably, then no harm has been done.

This past year I planted Alan's F5 seed of Astronomy Domine sweet corn inside a patch of Astronomy Domine that has been adapted to my garden. I detasseled the newly arriving corn. Alan's version averaged about 10 days later maturing than my version, and some of it was up to 3 weeks later. I was able to incorporate many individuals from the trial into my existing landrace. However, if I had willy-nilly intermingled the two versions of the same variety of corn as if they were commercial clones, I would have seriously impacted next year's corn harvest.

[Deleted]

The diversity issue is one I've been torn on. Should I keep a boatload of traits in the genepool to maintain more heterosis? But, would I be including genes that actually reduced productivity and vigor if I didn't select heavily enough? Also, like I said a while back, my "Nanapu" (my grandmother's affectionate name) corn is going to be bred for dual purpose as a pole bean support, so I'll have to select pretty strongly for stalk strength and bracer roots. But I figure I can be pretty lenient about plant & kernel color, exact row number, ear length, and kernel type. Maturity dates and strong 10-14 ft stalks with bracers are the only two traits I want to be uniform.

[oxbowfarm]

I figure you have to select for what you want or like otherwise its just a mishmash. If you keep everything the corn won't work for much. Offer the stuff you don't want to other folks or eat it or feed it to something. Clearly you have to get rid of a lot of the genes, thats what selection means.