Flint/Flour crossbreeding

[acxlll]

Hi,

I'm looking to start a corn landrace that will be able to mature in our short season and northern latitude in Latvia.
Actually - make it 2 landraces - flint and flour for different uses.
I want to throw a lot of genetics together and then select the best survivors over time.

The question now is - to mix flour and flint or not to mix them in the initial planting?

I know it is relatively easy to select for a recessive trait, just eliminate everything that shows the dominant trait and eventually you will have the recessive ones only. So flint, which as far as I know is recessive, will be easy to select.

However, I don't really know how to best separate the flour corn out of the mix. There will always be a small percentage that carries the recessive flint gene and when crossing with another carrier will make the flint trait appear. So no matter how many years I replant floury kernels only, I will still get some flint. Right?
Does anyone have any strategies for selecting for a dominant trait?

Am I setting myself up for a headache by mixing both types together? Would it be better to start with two separate populations right away? (although there is no guarantee that my initial flour corn seed will not have recessive flint genes hidden within)

[reed]

I'm doing something similar only I am selecting mine to be flint. I didn't know that flint was recessive so that is good for me. All I got to do is make my crosses and select the flint kernels. Are you sure abut that though? Seems to me that they are kind of quantative and can exist in varying amounts inthe same kernel.

As far as selecting for flour, assuming it is dominate is a problem cause if even one flint kernel shows up on an otherwise flour ear you know that the mother of that plant is carrying the flint so all of the other kernels are too. Only thing I can think to do is grow as large a population as you can and look for ears that have no flint kernels at all. Still I imagine you could be chasing the flint for a log time. 

[Joseph Lofthouse]

I mixed flint/flour when I started some of my landraces. They separate fairly easily after mixing. Though it seems easier to select for a pure flint than for a pure flour.

Genetically, it seems to me like the flint/flour trait is sorta codominant, and it is occurring in triploid tissue which muddles selection. Also, I think that there may be other genes involved, which modify things like where the soft starch is located. 

[Dale Wilson]

Joseph,
I'm very interested in this subject right now, and want to pick your brain about this.  We crossed Mandan Bride and Hopi Blue with various inbreds, no truly flint inbreds, but some pretty darn flinty, like CML103, LH51 and LH82.  One objective is to find the right balance between soft starch and hard starch for tortillas (not that we really understand what the right balance is quite yet).  I have a couple questions: 1) can we select kernels by candling or flotation on solution based on density? 2) When should we select? right now in the crossed seed?

It would seem like the cross with a homozygous flinty inbred, especially with the inbred as the female, might provide a good opportunity to simplify the population WRGT flinty/starchy genes.  If, for example, we kept only the most floury kernels (assuming that is possible) we could eliminate flinty genes that came from the OP side of the cross.

Also, you mentioned POSITION of soft starch.  Where can I get information on that?  One of the varieties we grew is Texas Gourdseed, with abundant soft starch at the kernel apex, so much it usually does not dent.  It will be interesting to see what happens when that is crossed with other things.  My thought is that for tortillas, we want plenty of soft starch, but maybe not on the surface where is subject to overly rapid alkaline degradation and loss.

[Joseph Lofthouse]

Dale:

My first suggestion is to get detailed feedback from people that have spent a lifetime making masa from corn. Find out what characteristics they value in their corn. The cost of a trip to the Hopi, pueblos, or Mayans would be more than amply repaid if you can gain wisdom about what makes a great nixtamalized masa corn. Perhaps there are people close to home that can give you feedback or seeds. I hope you seek them out and learn from them. There is little gained from developing an agrinomically pleasing corn, if people won't use it in the kitchen.

We've made tortillas from popcorn, the hardest of flints. After making tortillas from across the whole spectrum of available endosperm types my tribe prefers softer flour corns, because they are easier on equipment, and the muscles that operate it. The softer flour corns make tortillas that are more tender. Flint corns make rubbery, gritty tortillas. The soft flour corns make hominy that is more tender, and easy to eat. The soft flour corns make better cakes and cornbread. The flinty types make better grits.

If you don't mind doing destructive testing, cutting or breaking the kernels open is a great testing mechanism.

Flotation is an easy way to mass-select for density of corn kernels. Winnowing might also work if the air stream was very strong. Candling is great for selecting specific kernels from a mixed-heritage cob. If you don't introduce non-desirable seed traits into the population, then you don't have to remove them later on.

Because much of your current seed is F1, the seed will tend towards being homozygous in this generation. Next year, the seed will segregate wildly. That's the best year for doing selection. If you started with parents that are totally unsuitable for making masa, now would be a great time to eliminate them before they contaminate your project (unless they have unique agronomic traits that you want to retain). From the list of varieties, the two that I would prefer for tortillas are Mandan Bride, and Blue from Hopi. Soft flour corns are more susceptible to huitlacoche, and to animal predation.

In the crosses that are [inbred flint X open pollinated], you could select for floury kernels this year, which would help to minimize flint in the future.

You could learn a lot about the suitability of each variety by making a tortilla from say 40 kernels of each of the crosses. (I imagine nixtamalizing in the oven, in those little steel condiment cups, or steel measuring cups, and grinding in a mortar/pestle.

I don't notice the alkali dissolving the starch. I think because alkali preferentially targets protein, and the pericarp is protecting the endosperm when temperatures are hot.

[spacecase0]

I sure don't have a lifetime of making masa,
but I have done it a fair number of times,
and I have talked with people that have done more than me.
what Joseph said seems to match

as a side note,
if you have wood ashes you are using,
my advice is to boil out it separate and then pour out the liquid into another pan
then add the corn.
leaving the bulk ash in the mix is just a horrible mess.
and never use any aluminum pan anywhere near this.

[Tim DH]

We use wood ash straight off. ... It's no problem if the seed quality is good.

We sieve any large lumps out of the dry ash first. (In fact we do this once every few months and have a large jar of sieved ash in the kitchen which has a scoop in it.)

If the seed quality is poor then it can rupture in the ash, which adheres to the ruptured surface. But normally seed comes through whole, even after an overnight soak. The ash washes off very cleanly, even if you aren't trying to rub the skins away.

Apart from Corn, we also ash prepare beans to soften the skin. Pre-boiling the ash and decanting it would be a pain.

Tim DH

[Dale Wilson]

Joseph,

Regarding flint/flour balance in the new populations we made, for the time being the focus will be mass-selection for earliness.  But we have enough resources only to do that with a few of the populations.  For some of the others the plan is to grow just a hundred or so plants and try to chain-sib them, with little or no selection.  But at least that will propagate and break up linkages.  One thing that occurred to us is that we don't necessarily need to achieve a good flint/flour balance within kernels.  Since kernels are ground to make masa, the proper balance could be achieved with heterogeneous kernels.  In other words, we could adjust, or even customize seed (say, using top-cross) to achieve the flint/flour balance for particular consumers.

Dale

[Dale Wilson]

Dear acxIII,

Sorry this reply is so late, I have been too busy hoeing my corn nurseries, and now picking and shelling.  But corn breeding is slow in any case.

Regarding selection for a dominant trait, you will have to self pollinate a number of plants and select the ears  that are 100% floury.  Seed from those should breed true for the dominant trait.  Below is an example of what we did in our little tortilla corn consortium.

We crossed Pioneer 207 (Iodent progenitor inbred) with Bloody Butcher in 2021, and chain-pollinated in 2022 and 2023 to shuffle the genetic deck and select for earliness.  We determined that the family makes good tortillas, is earier, and makes beautiful kernels (207 seems to accentuate color...and it is EARLY).  But we wanted an OP population that makes only red and purple kernels.  So this year I planted only purple kernels and selfed about 100 plants.  I discarded ears that had yellow or white kernels, and kept (among other selections) ears that look like Bloody Butcher.

Unless there is something I don't understand about the genetics of kernel color (which is quite possible) we should have a population that breeds true for the appearance of Bloody Butcher, but is earlier and shorter.  Next year I will chain pollinate the mixed seed from the selected ears to finish the variety.  Hopefully I won't see any yellow or white kernels!

Dale