What to expect from flour x sweet

[reed]

Started to put this in raymondo 's flour x flint thread but didn't want to hijack it with adding in sweet. I detasseled Painted Mountain and crossed it to early se and su sweet corns. It dired down and the f1 generation is now about 4 inches tall. I didn't get any wrinkled kernels and didn't really expect to. I did notice the seed has a more flint looking appearance than another patch of PM that pollinated itself. 

Any guesses what the f2 generation will look like? Can I expect some percentage of wrinkled kernels? 

[Joseph Lofthouse]

In the F2, if you allow it to self pollinate, you can expect 3/4 of the kernels to be floury, and 1/4 to be sweet (wrinkled when dry). Among the sweet kernels you can expect 1/4 of them to be sugary enhanced.

If you detasseled the F2 and pollinated it with a sugary enhanced variety, then you could expect 1/2 of the kernels to be sweet.

[DarJones]

3/4 of the kernels will be SU/SU, or SU/su in other words, not a sweet kernel.
1/4 of the kernels will be su/su, or sweet kernels
3/4 of the sweet kernels will be floury endosperm which tastes nasty at the milk stage
1/4 of the sweet kernels will be flint endosperm which tastes sweet at the milk stage

This gets us to 1 kernel out of 16 that should be selected to grow.
If the cross was with an se/se line, then from the selected sweet flint kernels:
1/4 will be se/se plus su/su plus fl/fl

in other words at the F2, 1 kernel in 64 will have the desired genotype. It is not possible to reliably select that 1 in 64 based on any tests short of gene sequencing so you wind up growing the kernels which are su/su and fl/fl because they are visually recognizable. Then you have to self the plants to get the 1 in 4 that will produce se+.

The only caveat is that there are multiple floury genes so in some cases it may be much worse odds than above. Floury is not entirely dominant so make a point of picking the most translucent kernels at the F2 because they are less likely to have one of the floury genes. An ear of corn with 500 kernels should yield about 20 kernels with the desired phenotype. Be very picky, it will save a lot of time later.



I am working on bringing se/se into Country Gentleman. Barring incident, this year I will have 1 or 2 plants out of 20 that produce the desired combination. With those F3 seed, I will grow a bulk quantity of F2 seed next year and use the F3 as a pollen source which will yield corn that is 1/2 se/se and 1/2 se/SE. The following year, I will be able to isolate enough pure se+ to produce breeding stock.

[reed]

Aug 4, 2015 15:36:17 GMT -5 DarJones said:

The only caveat is that there are multiple floury genes so in some cases it may be much worse odds than above. Floury is not entirely dominant so make a point of picking the most translucent kernels at the F2 because they are less likely to have one of the floury genes. An ear of corn with 500 kernels should yield about 20 kernels with the desired phenotype. Be very picky, it will save a lot of time later.

Thanks for all the good info. That's very interesting about the different floury genes. Of the threes ears I planted from one in particular even at the F1 looks more flinty that the others and definitely more flinty than my other PM seed. It also had, at least to me, a slight sweet taste even past the milk stage.  I have about a dozen plants of it about a foot tall in another spot. The other ears tasted rather like paste but I planted them for a little more diversity. I also have some ears of Cascade Cream Cap x se, maybe I it isn't too late to stick a few of them in the ground. Trying to see if it might really be possible to grow two generations in one year is a big part of the project. 

I doubt if I go on with the Oaxacan or Hopi x se, those ears are much larger and taking too long to dry down. It is easy enough to grow corn but to be sustainable in small populations I'm thinking it has to be very diverse, never really settling into a stabilized variety. Also I am finding that growing corn and growing corn seeds are in a way not exactly the same thing. 

I didn't really anticipate crossing PM to sweet to bring about anything particularity worthwhile but now I'm not sure. I'm pretty sure that none of the dehybridizing se or any of the su would have any chance of two crops in one year. I'm starting to get visions of a short season, drought tolerant  sweet corn with long skinny 8, maybe 12 row ears. That way I can not only breed two generations per year but more important I can snatch up viable seed before the coons, mold or bugs. Another bonus would be that limited space could be double used, growing something else before or after the corn.