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stella1751
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Silly Question; Sorry!

I tried to find the answer to this question online, but apparently I'm not using the right search terms: If hybrids don't breed true, how do the seed vendors produce seeds that breed true?
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DoubleDogFarm
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Highly controlled artificially cross-pollinated plants. It's the second generation that doesn't breed true.

Hybrid Seed Production in Tomato
https://www.avrdc.org/LC/tomato/seedhybrid.pdf

Eric

TZ -OH6
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How do you get a new true breeding variety? By throwing out lots of plants and only saving seed from the one with the characteristics you want.

If I crossed Brandywine with Cherokee Purple (tomatoes) the seed would be the equivalent of the hybrid seed sold by venders (F1 generation). All plants would grow out be the same.

Step 2) Planting many seeds saved from the hybrid F1 would give me a wide range of characteristics and I would save seed from any of those plants (F2 generation) that were good and grow them out as separate lines to try to stabilize the prefered characteristics. For this example I'll save seed from the best plant only.

Step 3) Grow out several plants from the one above, keeping seed only from the best plant (F3 generation)

Step 4) Grow out several seeds from the above best plant, weeding out any that showed variation from expected and keeping seed from the best (F4 generation).This should be pretty stable at this point but there still can be some hidden heterozygous genes, especially for flavor.

Any variation is pretty much selected out by the F7 generation, so the variety is stable by that time.

Breeders generally do this for several lines from a cross (assuming more than one is good). Some of the stable varieties from Brandywine x Cherokee Purple are Gary'O Sena, Liz Birt, Dora, Brandokee, and Bear Creek.

Brandywine is a pink fruit with potato leaves and Cherokee purple is a "Black" fruit with regular leaves so the various stable offspring lines differ in these triats as well as flavor, size and productivity.


Seed farmers/venders get the varieties already stabilized from the breeders and just have to make sure the fields of each variety are isolated from others so bees can't mix up the pollen.

DoubleDogFarm
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Seed farmers/venders get the varieties already stabilized from the breeders and just have to make sure the fields of each variety are isolated from others so bees can't mix up the pollen.
This is the highly controlled isolation part.

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stella1751
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DoubleDogFarm wrote:Highly controlled artificially cross-pollinated plants. It's the second generation that doesn't breed true.

Hybrid Seed Production in Tomato
https://www.avrdc.org/LC/tomato/seedhybrid.pdf

Eric
This is what I was looking for. Thanks!
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garden5
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Wow, great info in this thread. Thanks, TZ, for the detailed explanation of tomato breeding, I've wondered what would happen with successive seed carryover.
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gixxerific
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Nice work THZ

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TZ - I just keep learning all kinds of things from you. Thanks!

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stella1751
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Yeah, thanks, TZ. I was so excited about Eric's .pdf file (it has pictures), that I forgot to thank you, too. I think I'm still at the stage where I need illustrations :oops:
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No pictures but here are my tasting notes from this morning for some of my second generation (F2) Lime Green Salad x Green Giant grow outs(all seed from one hybrid plant grown last year)

plant
1-Tastes Like crud
2 -Tastes worst than #1
3 - God that's nasty
4 - Neutral
5 - Bland and watery
6 - sour and watery
7- Ok, keep seeds
8- Tastes like #3
9 -Hey finally one that taste good, meaty and firm, Woo Hoo!
10-Bad
Last edited by TZ -OH6 on Tue Aug 10, 2010 10:42 pm, edited 1 time in total.

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stella1751
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I laughed out loud at this one, TZ; I'm not kidding you. You completely caught me by surprise :lol:
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garden5
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stella1751 wrote:Yeah, thanks, TZ. I was so excited about Eric's .pdf file (it has pictures), that I forgot to thank you, too. I think I'm still at the stage where I need illustrations :oops:
Ha, I don't think anyone ever gets tired of illustrations! Good post, DDF.

TZ, it sounds like tomato breeding isn't as glamorous and we imagine :lol:. Good luck with the good one.
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gixxerific
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Sounds good and than bad and than worse and than maybe okay and than bad again THZ. If only I had the room and the time I would dabble in breeding. But until than I will just absorb as much as I can from you. :D

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Yeah, space (well, actually lighting) is my main stopping factor as well. I'd like to have a go at developing my own variety, but I'd need at least another 3 grow lights (which I'll probably get anyway :roll: ) and a lot more space :lol:. Well, slowly but surely I'll keep expand in the growlight setup and, in turn, the gardening experiments.
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TZ -OH6
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You can cut a lot of corners with space because all you need is a single stem, so plants can be spaced less than a foot apart if needed, and you can pull the plants after you taste the first couple of fruits. That means you can cram them in with your other plants for the first half of the season. Another option is to play with dwarf varieties, which can be grown full term in 5 gal buckets or grow bags alongside the driveway etc.

I grow the F1 plant (hybrid from my cross) in a 4" pot starting in winter then take seed from the first little fruit, which can be planted in time for summer grow out.

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stella1751
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Suppose I wanted to reverse the process? If I have an F1 pumpkin I seriously like and want to keep seeds from it for fun (to experiment with selection), would the next generation revert to either of its two parents and the third generation remain fixed? Or will that pumpkin's offspring always remain questionable, generations down the road?
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TZ, It is my understanding that if a variety has been grown out to F7 and is considered an open pollinated variety, the desired characteristics of the variety can deteriorate after many generations. The size may get smaller. The taste may become bland. The color may change. The disease resistance
may change. I think I have read that many people who have saved pure seed over many generations probably are not growing the same tomato as when they first started saving seed. Is that true? If so, why? What breeding tricks can be performed to maintain the genetic characteristics the variety was first bred for?

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Okay, I've read through this one a couple times and still not positive on this............. I bought an F1 hybrid cantaloupe plant. Will the seeds from the fruit from that plant germinate and produce fruit? If so will the fruits be the same as the ones from the plant I bought this year?

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Short answers:

Yes, you can grow seeds from a hybrid. They will be more or less different than the hybrid depending on how different the parents of the hybrid were. In school we are taught that hybrids can't reproduce (horse x donkey = sterile mule), this is generally true with different species but with vegetables the different varieties are the same species so it is like two people having a child.

Growing out a hybrid will not get you back to the parents because each gene segregates independently of the others (more or less). It is like putting into a bag 100,000 pink balls, and 100,000 green balls, (the hybrid) shaking up the bag and then trying to pullout 100,000 pink balls.

Will an open pollinated variety degrade over time? Not on its own. The chance for a random mutation is about 1 in a million genes per generation, or one per one million seeds for a given gene.

The father of modern tomato breeding, Alexander Livingston, "discovered" that once a variety is stable it is that way forever as long as you keep other varieties away from it, so he contracted seed growers that would only grow his varieties in different fields/farms. It was also the way that he was able to select out new varieties and stabilize them by selecting seeds from from the best plants rather than saving seeds from the best fruits from differnt plants.

https://www.archive.org/details/livingstontomato00livi

You can still buy most of these old varieties from Victory seeds and others.

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So, I may not be able to stabilize a variety that is exactly like the F1 plant that I started with (as the characteristics will vary through F2, F3, etc.) but I may be able to create a variety with characteristics close to those of the F1 plant. Is this right?
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TZ -OH6
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Exactly, but it is still a god idea to grow out several/many F2s next to the original F1 to select for similarities.

It isn't that difficult with modern hybrids because for the most part both parents were very similar (round, red, productive, average flavor) and the hybridizing is mainly to produce the disease resistances (which most likely won't all be transfered intact to the offspring you end up with.) Grape cherry from the supemarket is like that. What you grow from saved seed is almost identical to the hybrid.


Burpee (who believes that hybrids are better in all cases) goes the other direction and makes hybrids that mimic the open pollinated varieties. Bucks County F1 is identical to red brandywine from what I hear.

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