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Old December 9, 2018   #166
rhines81
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Fred, you are confusing the heck out me! Which is it?


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This is why I do not believe the practice of calling OPs hybrids is common, and why I do not believe that any large company, in particular, would be so stupid as to lie.

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I think calling OP varieties "hybrids" is a pretty common "error"
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Old December 9, 2018   #167
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The thought has often come to my mind, when considering buying an F1 from a vendor of 1 person, 3rd party vendors online or a vendor from China, am I really getting an F1 or a F1 that has been dehybridized.
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Old December 10, 2018   #168
Fred Hempel
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I think it is a common "error" by seed RE-SELLERS. For example, I occasionally find companies who have clearly purchased bulk seed calling my OP varieties hybrids.

I do not think it is a common practice by seed companies who are offering varieties that THEY THEMSELVES HAVE BRED.

Sorry for the confusion.



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Fred, you are confusing the heck out me! Which is it?
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Old December 10, 2018   #169
Fred Hempel
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Disease resistance is very tricky, because there are cases where being homozygous for a resistance gene will result in a "cost" (less vigor, etc.). However, there must also be cases where homozygous is better. That said, disease resistance stacking at many loci is probably both very difficult to achieve, and will lead to vigor costs. And it is important to note that vigor is also one general way to "fight" disease, so reducing vigor reduces general disease resistance.

One reason I think I generally see better "general" disease resistance in hybrids is because my experience tells me very clearly that plant vigor is generally enhanced in hybrids -- probably due to the genetic diversity increase in hybrids (because the two parents will have alternate forms of genes at many loci, and thus more genes and more "solutions" to problems)

I do find that OPs have better resistance in earlier generations, when they are still genetically more diverse. I have had countless examples where OPs I am developing get "weaker" over time. My general selections are based on taste, but I still always try to also select for vigor when I have a number of plants in a population with equivalent taste.

I do not choose parents specifically to be more productive, and I don't follow disease markers or "vigor" markers.

I do try to start with parents that are generally decent with regards to vigor and disease resistance. And my parental lines clearly do have some genes that have been specifically put there by other breeders. I just don't follow them molecularly. But, I assume that I select for them in the field.


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Do you consider (1) as inevitable or is it more so by design? I mean if genes were stacked deliberately to get disease resistance, it stands to reason they will outperform.


Regarding OP's, do you find that they have better disease resistance in early generations of breeding( when less genetically stable), and that it is harder to find that by F5,6 and beyond? Or did the OP varieties you compared, simply have less in the way of disease resistance genes from the early stages? (less than tailored for resistance F1s I mean)


As regards productivity, I haven't been able to generalize about F1's being more productive and as I understand it, that is dependent on some very specific genes being present in the two parents. So I wondered, did you choose the F1 parents' genetics deliberately to get the 'extra productive' effect? And in the created OP's, would you generalize that there is a decline in vigor as they become closer to stable?
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Old December 10, 2018   #170
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I think when it comes to hybrids, it is best to go with companies that are "professional". And that includes vendors like TGS, Johnny's and High Mowing (small companies).

While it is true that a 1 person mom-and-pop seed companies may be selling legit hybrid seed, I think your risk goes up when purchasing, particularly on Etsy or Ebay.

That said, I have a seed business that is by most all measures mom-and-pop, but I do sell legit hybrid seed. So, there are exceptions to every rule.

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The thought has often come to my mind, when considering buying an F1 from a vendor of 1 person, 3rd party vendors online or a vendor from China, am I really getting an F1 or a F1 that has been dehybridized.
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Old December 10, 2018   #171
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From what I am seeing in a Google search, I can not find any hybrid Porter cherry tomatoes. Seems like maybe a mis-labeling.

You won't find much on Google because the nursery (Bonnie Plants) made up the name. Porter is an old Texas seedsman from the Great Depression era and he and his company never marketed a "Porters Dark Cherry" that started this.
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Old December 10, 2018   #172
rhines81
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Quote:
Originally Posted by Fred Hempel View Post
I think it is a common "error" by seed RE-SELLERS. For example, I occasionally find companies who have clearly purchased bulk seed calling my OP varieties hybrids.

I do not think it is a common practice by seed companies who are offering varieties that THEY THEMSELVES HAVE BRED.

Sorry for the confusion.
Now that makes perfect sense
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Old December 10, 2018   #173
Zone9b
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Originally Posted by Fred Hempel View Post
Disease resistance is very tricky, because there are cases where being homozygous for a resistance gene will result in a "cost" (less vigor, etc.). However, there must also be cases where homozygous is better. That said, disease resistance stacking at many loci is probably both very difficult to achieve, and will lead to vigor costs. And it is important to note that vigor is also one general way to "fight" disease, so reducing vigor reduces general disease resistance.

One reason I think I generally see better "general" disease resistance in hybrids is because my experience tells me very clearly that plant vigor is generally enhanced in hybrids -- probably due to the genetic diversity increase in hybrids (because the two parents will have alternate forms of genes at many loci, and thus more genes and more "solutions" to problems)

I do find that OPs have better resistance in earlier generations, when they are still genetically more diverse. I have had countless examples where OPs I am developing get "weaker" over time. My general selections are based on taste, but I still always try to also select for vigor when I have a number of plants in a population with equivalent taste.

I do not choose parents specifically to be more productive, and I don't follow disease markers or "vigor" markers.

I do try to start with parents that are generally decent with regards to vigor and disease resistance. And my parental lines clearly do have some genes that have been specifically put there by other breeders. I just don't follow them molecularly. But, I assume that I select for them in the field.
That explains a lot. In a couple of occasions, I have grown hybrids that I liked and were quite productive. However, to keep growing them I had only one vendor to buy from and they had no other seeds I was interested in. It was hard for me to justify buying a single packet of seeds along with shipping, so I just starting savings seeds. It is easy for me to get a few generations away from the original seeds, given that I grow 2 crops a year and can save seeds twice a year. But ultimately, they got to a point where their performance was so poor that I just give up on them. Thanks
Larry
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Old December 11, 2018   #174
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Originally Posted by Fred Hempel View Post
I do find that OPs have better resistance in earlier generations, when they are still genetically more diverse. I have had countless examples where OPs I am developing get "weaker" over time.
I wonder if this is simply a result of the fungi/bacteria themselves adapting, much in the same way we see bacteria that infect humans adapt to overzealous use of anti-biotics, and not so much a genetic trait, or "problem" of OP breeding?

I suppose it would be an interesting experiment to see if the later generations which appear to lose some of their disease resistance when grown by you locally, gain it back if grown in other parts of the county/state/country/world
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Old December 11, 2018   #175
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I think you are right that changes in field conditions do partially explain the "reduced resistance over time" that we sometimes see.

There may be cases where pathogens evolve in a field after successive years of tomato growing (even if you are practicing crop rotation). But this is hard to separate from the effects of simple buildup of diseases that can occur in a field over time if tomatoes are consistently grown.


Either way, the increasing genetic uniformity that comes with the selection of an OP variety is not the sole reason one might see poorer vigor and/or disease resistance over time.

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I wonder if this is simply a result of the fungi/bacteria themselves adapting, much in the same way we see bacteria that infect humans adapt to overzealous use of anti-biotics, and not so much a genetic trait, or "problem" of OP breeding?

I suppose it would be an interesting experiment to see if the later generations which appear to lose some of their disease resistance when grown by you locally, gain it back if grown in other parts of the county/state/country/world
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Old December 11, 2018   #176
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Originally Posted by Fred Hempel View Post
I think you are right that changes in field conditions do partially explain the "reduced resistance over time" that we sometimes see.
There may be cases where pathogens evolve in a field after successive years of tomato growing (even if you are practicing crop rotation). But this is hard to separate from the effects of simple buildup of diseases that can occur in a field over time if tomatoes are consistently grown.
Either way, the increasing genetic uniformity that comes with the selection of an OP variety is not the sole reason one might see poorer vigor and/or disease resistance over time.

Does this mean that my old school attempts to improve the productivity of an OP variety in my harsh growing conditions is of little, if any, value? I continue to choose the largest tomato from the best vine to save seeds from. This has seemed to work well for me on at least one variety. This fall season it produced its largest tomato yet after growing for approximately 7 seasons, also its productivity is very good. Thanks,
Larry
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Old December 11, 2018   #177
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I select based on plant total production and usually toward the end of the season. It's not always the largest fruit I choose but not the runt either.


Each year I test new OP varities to see which work best for me and they are always compared to the better hybrids for production. Not that close yet except for cherry tomatoes but I guess that is why the hybrid seed business can continue over a 100 years.

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Old December 11, 2018   #178
Fred Hempel
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I think continued careful selection of OP varieties to improve them is well worth it!

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Does this mean that my old school attempts to improve the productivity of an OP variety in my harsh growing conditions is of little, if any, value? I continue to choose the largest tomato from the best vine to save seeds from. This has seemed to work well for me on at least one variety. This fall season it produced its largest tomato yet after growing for approximately 7 seasons, also its productivity is very good. Thanks,
Larry
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Old 1 Week Ago   #179
frogsleap farm
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Originally Posted by Zone9b View Post
Does this mean that my old school attempts to improve the productivity of an OP variety in my harsh growing conditions is of little, if any, value? I continue to choose the largest tomato from the best vine to save seeds from. This has seemed to work well for me on at least one variety. This fall season it produced its largest tomato yet after growing for approximately 7 seasons, also its productivity is very good. Thanks,
Larry
There's no question that selecting for healthy plants in disease and stress prone areas can lead to improved tolerance to some diseases and general improvement in plant health. However meaningful tolerance to some pathogens (e.g. late blight, fusarium wilt and TSWV) require specific resistance genes. I've found that a combination of phenotypic selection for plant health and incorporation of resistance genes via molecular markers gives the best result.

All the fruit on a plant has the same genotype, so there is no possible benefit from saving seed from the largest vs smallest fruit on an individual plant.
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Old 6 Days Ago   #180
hl2601
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So if all the fruits on one plant have the same genotype-which are the best to select for seeds? Earlier, later, largest,very ripe?
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