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Old March 27, 2017   #1
BenGreen
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Default breeding 2 seasons per year

A few questions for the more experienced breeders: if you want to increase the speed of your breeding programme, can you do a cultivation in summer outside and winter in heated greenhouse? and thus capture 2 seasons in a year?

The thing I am most interested in is whether selection in the greenhouse will have undesired side effects: such as unintentionally selecting for different temperature tolerance. I know from the Netherlands that they do winter cultivation with lights and heat and it never reaches the quality of the summer crop,
but does it influence selection significantly?

I am located at latitude 39,9248, which might have an influence on winter sun hours.

Does anyone here do winter cultivations in a greenhouse for their breeding?
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Old March 28, 2017   #2
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AKMark is in Alaska and breeds his own tomatoes. He grows most of his tomatoes in a greenhouse and also has some outdoors. Why not check with him if he does not find this thread on his own.
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Old March 28, 2017   #3
PaddyMc
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How big a greenhouse do you have? How many seg's are you thinking of growing?
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Old March 28, 2017   #4
AKmark
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I can easily do two generations per year, and three if I send seed to someone who can grow in the winter. We do look for traits such as cold tolerance, production, and early fruit set. The beauty of a GH is we can tailor the environment, I have never got accidental cross pollination either.

I am so done by October I would never do any winter crops, too cold to heat our GH's up here, other places further south I would do it.
Piece of cake.
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Old March 29, 2017   #5
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if you have access to a greenhouse, two generations/yr is easy, three is possible. If you are advancing generations on early filial generations (i.e. F2-F4), you will need to be careful to advance multiple progeny per generation to manage "genetic drift", unless you are prepared to accept that risk, such as with a single seed decent strategy. When I employ a 2/3 generation/yr strategy to fine tune F5-F7 lines, I normally go with just a couple of progeny per line, and confirm uniformity. There is still some risk, but I believe it is properly balanced with the goal of "fixing"/stabilizing the inbred genotype.
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Old April 30, 2017   #6
katwest
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Hi, can you explain the concept of genetic drift a bit more? Not sure I'm following the risk...
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Old April 30, 2017   #7
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Quote:
Originally Posted by katwest View Post
Hi, can you explain the concept of genetic drift a bit more? Not sure I'm following the risk...
Genetic drift is the inadvertent loss of genetic variation due to small sample size. For example in a F2 generation derived from a F1 of dis-similar parents - there will be abundant genetic variation among F2 family members, each carrying a different combination of traits from the F1 parents. If you can only grow out 2-3 F2 individuals, you have a very small sample of the potential gene/trait combinations available - and have a high risk of not capturing the ideal combination you are looking for.

Last edited by frogsleap farm; April 30, 2017 at 02:49 PM. Reason: typo
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Old May 2, 2017   #8
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Interesting - thanks for the explanation!
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Old July 28, 2017   #9
crmauch
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Quote:
Originally Posted by frogsleap farm View Post
Genetic drift is the inadvertent loss of genetic variation due to small sample size. For example in a F2 generation derived from a F1 of dis-similar parents - there will be abundant genetic variation among F2 family members, each carrying a different combination of traits from the F1 parents. If you can only grow out 2-3 F2 individuals, you have a very small sample of the potential gene/trait combinations available - and have a high risk of not capturing the ideal combination you are looking for.
How many of the F2 generation would you usually plant? And of the resulting plants how many would you select to go forward? I'm thinking your numbers would get very large, fast. If in the F2 you grew 10 plants and 3 of those had traits you were looking for and grew out 10 of each of those for the F3 (you'd now be at 30 plants). If in the F4 you're still looking to avoid unwanted drift you could be looking at 90 plants. Are these the kind of numbers you would be talking about?
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Old March 30, 2017   #10
Darren Abbey
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Quote:
Originally Posted by BenGreen View Post
The thing I am most interested in is whether selection in the greenhouse will have undesired side effects: such as unintentionally selecting for different temperature tolerance.
Alternating selection forces can have the impact of selecting for plants that can handle a broader range of environments, or get your population stuck into something you don't want. The key is having sufficient plants at each stage to avoid too much drift. You can always keep seeds from previous generations to step back to if something goes awry.

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Originally Posted by BenGreen View Post
Does anyone here do winter cultivations in a greenhouse for their breeding?
I don't have a greenhouse, but I have grow-lights setup in my basement. I've done several chile crosses this winter, as well as ensured the selfing of the best from the previous generation of a project.

Next year I'll probably be selecting and growing micro-sized tomato plants in my basement too.
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Last edited by Darren Abbey; March 30, 2017 at 02:26 AM.
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Old April 26, 2017   #11
BenGreen
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Quote:
How big a greenhouse do you have? How many seg's are you thinking of growing?
We have a 200m2 greenhouse, but we actually use it as our nursery so it does not have too much cultivation area. I am already using it to do 2/3 generation of pot tomatoes, but those are on the tables with a more uniform temperature. So the question was mostly about soil temperature.

Thanks to all others for the very informative replies, we are simply going to give it a try
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Old April 26, 2017   #12
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Let us know how it goes for you! Good luck!
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Old August 1, 2017   #13
KarenO
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Thank you very much, I was hoping that would be the case, I thought it might be.
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Old August 23, 2017   #14
Brent M
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I've just grown 3 generations in about a year using a heated greenhouse and LEDs. It's easy to get 2 generations where I live in Arkansas. No longer than 4 months per generation. But, IMO, it depends on which generation you're growing. F2 needs a lot of plants for selection. This is the most important generation for selection. Would never do a winter greenhouse grow at F2.
Diversity tightens quickly after F2 though. My greenhouse grow this past winter was 10 plants at F4 and it's harder to make selections due to how the plants grow vs full summer sun. I won't do again unless I'm at F6 and feel it's pretty tight at that point. It's not worth risking all of the work prior to it IMO. But yeah, easily 2 generations in full sun is easy for me.
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