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Old July 12, 2017   #1
StrongPlant
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Default Heterosis

When it comes to genetics heterosis phenomenon is the one I've probably read the most about.And it's still not completely clear why it occurs.
I've seen it in action in tomatoes,but I noticed one interesting thing.
I made 3 crosses,the same strain of s.pimpinellifolium with 3 different s.esculentum varieties.Thing is,the cross with esculentum parent which was the most inferior in terms of yeld and vegetative growth gave the most vigorous and high yielding F1 out of the 3.Why would this be?
To me it made sense that if 2 parents are both superior genetically,that would make a better F1 then if one of the parents is inferior.
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Old July 14, 2017   #2
crmauch
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Originally Posted by StrongPlant View Post
When it comes to genetics heterosis phenomenon is the one I've probably read the most about.And it's still not completely clear why it occurs.
I've seen it in action in tomatoes,but I noticed one interesting thing.
I made 3 crosses,the same strain of s.pimpinellifolium with 3 different s.esculentum varieties.Thing is,the cross with esculentum parent which was the most inferior in terms of yeld and vegetative growth gave the most vigorous and high yielding F1 out of the 3.Why would this be?
To me it made sense that if 2 parents are both superior genetically,that would make a better F1 then if one of the parents is inferior.
I remember reading a book about breeding that overall wasn't all that useful as it was mainly about breeding grains and mass selection.

However, the author stated something at one point, paraphrasing here (breeding inferior to inferior is almost never useful, superior to superior is obvious and beneficial, but some of the most surprising and beneficial results are breeding inferior to superior). He didn't explain why.

If I had to guess, I would say that the inferior has so many homozygous genes that are slightly harmful that the hybrid created eliminates all these suppressed homozygous impediments allowing the hybrid result to be drastically improved.
I am somewhat surprised that you've seen so much improvement. I'm under the strong impression that though tomatoes do suffer some inbreeding suppression, that it wasn't that significant (as compared to corn, etc).

the Wikipedia article about heterosis was good and talked about the ideas of dominance/ over-dominance and epigenetics.
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Old July 14, 2017   #3
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I remember reading a book about breeding that overall wasn't all that useful as it was mainly about breeding grains and mass selection.

However, the author stated something at one point, paraphrasing here (breeding inferior to inferior is almost never useful, superior to superior is obvious and beneficial, but some of the most surprising and beneficial results are breeding inferior to superior). He didn't explain why.

If I had to guess, I would say that the inferior has so many homozygous genes that are slightly harmful that the hybrid created eliminates all these suppressed homozygous impediments allowing the hybrid result to be drastically improved.
I am somewhat surprised that you've seen so much improvement. I'm under the strong impression that though tomatoes do suffer some inbreeding suppression, that it wasn't that significant (as compared to corn, etc).

the Wikipedia article about heterosis was good and talked about the ideas of dominance/ over-dominance and epigenetics.
In tomatoes it's definitely less dramatic then in corn,but...I've read that crosses of domestic tomato with some strains of S.pennellii were quite impressive in terms of vegetative frowth,i.e. biomass acumulation.

The cross I mentioned has such fast growth,that is now over 4m tall,while both parents are just reaching 2m.Planted at the same time of course.
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Old July 20, 2017   #4
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The cross I mentioned has such fast growth,that is now over 4m tall,while both parents are just reaching 2m.Planted at the same time of course.
That sounds impressive for growth, but are you also seeing differences in flower production and fruiting? I have heard of cases outside of tomatoes where the the hybrid was very vigorous, but not particularly fruitful (the Jostaberry is the one that comes to my mind [if you're not familiar it's a hybrid of black currant and gooseberry, compared to gooseberry it's a monster of a plant, but not very fruitfull])
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Old July 21, 2017   #5
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That sounds impressive for growth, but are you also seeing differences in flower production and fruiting? I have heard of cases outside of tomatoes where the the hybrid was very vigorous, but not particularly fruitful (the Jostaberry is the one that comes to my mind [if you're not familiar it's a hybrid of black currant and gooseberry, compared to gooseberry it's a monster of a plant, but not very fruitfull])
I actually have jostaberry in my garden,can't say anything for productiveness yet as it started producing only this year.

While the hybrid I mentioned has smaller fruit,and even smaller total fruit weight per truss than the parent with higher yield/truss,it is so vigorous that when the total yield per plant is taken into account,it is higher.
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Old July 24, 2017   #6
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In tomatoes it's definitely less dramatic then in corn,but...I've read that crosses of domestic tomato with some strains of S.pennellii were quite impressive in terms of vegetative frowth,i.e. biomass acumulation.

The cross I mentioned has such fast growth,that is now over 4m tall,while both parents are just reaching 2m.Planted at the same time of course.
I can confirm that the F1 cross of Solanum Pennellii x domestic tomato is VERY cool and has impressive growth. I am using it to develop a possibly drought tolerant tomato that thrives in my climate with my soil. So far i am VERY impressed. Can't wait until the F2!

http://tomatoville.com/showpost.php?p=656562&postcount=5
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Old July 28, 2017   #7
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I can confirm that the F1 cross of Solanum Pennellii x domestic tomato is VERY cool and has impressive growth. I am using it to develop a possibly drought tolerant tomato that thrives in my climate with my soil. So far i am VERY impressed. Can't wait until the F2!

http://tomatoville.com/showpost.php?p=656562&postcount=5
If pimp x lycopersicon is this vigorous I can only imagine what the cross with penellii,which is more distantly related,is like.My cross is currently 5m tall and 15th truss is ripening...It's a monster.The fruits are 18g and there's 20 on avarage on each cluster.That's over 5kg of deliciously sweet cherry tomatoes,and counting.My other hybrids have more than 5kg so far but I doubt they'll keep up with this monster for long.
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