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Post by kazedwards on May 28, 2016 16:32:10 GMT -5
So I have two projects going on right now. One is TGS and the other is the Jalapeño Cross that showed up last year. The TGS I will more than likely keep everything that grows and keep general notes on the whole project. I might separate it in to different categories once the plants get to mature size. The Jalapeño Cross is in the F3 stage so I need to start thinking of ways to select and organize this project into something that can be reviewed in future. What are different ways of doing this? Also what are different ways to measure heat levels in peppers besides eating them?
I was thinking of breaking the F3s into groups or families. Growing the F4s next year and then narrowing down to new varieties from there. Or should I start separating and choosing varieties this year?
Any help is great.
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Post by darrenabbey on May 31, 2016 21:47:14 GMT -5
What are your goals for your pepper project? I like the idea of screening lots of F2s (even if over several years) to find the closest match to the goal before moving on to later generations.
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Post by kazedwards on May 31, 2016 23:08:27 GMT -5
Well last year the F1 was great. Heat and taste like a jalapeño with the same thickness but a light green color and larger. I would like something similar to that as well as one that has thinner walls perhaps. Both with the taste and heat of a mild jalapeño. Here's a picture of the F1 fruit last year and a jalapeño. Some of the fruit were larger than this too but most were that size.
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Post by darrenabbey on May 31, 2016 23:27:41 GMT -5
Stabilizing the F1 phenotype can sometimes be difficult. There is the possibility that some key trait is caused by the heterozygous condition at some gene. I've got a carrot line I'm working with where the color I like best is [pretty definitely] a heterozygous trait, so no matter how many generations I select for the trait it will never stabilize. I'm fine with always saving seed from the heterozygous individuals and having the resulting population being a mix each cycle.
That said, generally the only way to find out if this will be an issue is to keep selecting for the type you like, but pay attention to the distribution of off-types in each generation. Maybe photos of fruit from each plant, with some sort of standard scale item in each photo for later comparison.
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Post by kazedwards on Jun 1, 2016 9:42:54 GMT -5
Why are heterozygous traits hard to stabilize?
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Post by nicollas on Jun 1, 2016 12:58:43 GMT -5
Because Aa x Aa has as much homozygous (AA and aa) than heterozygous (Aa)
So each self pollination will lost half of heterozygous state. And in a crosspollinated population, you need homozygous alleles to generate heterozygous alleles in next generation (AA x aa = Aa)
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Post by darrenabbey on Jun 1, 2016 23:27:35 GMT -5
Why are heterozygous traits hard to stabilize? Here's a hypothetical scenario... AA x aa -> [F1] Aa Aa x Aa -> [F2] 1 AA : 2 Aa : 1 aa To be sure of continuing to get the heterozygous trait (Aa), you would have to actively select for it in each generation. With small populations, genetic drift will take over when you stop selecting for Aa. This can result in the population randomly becoming all AA (or aa) in a few generations. (With a theoretically infinite population and random crossing, the heterozygous condition would be maintained at 50%.) Homozygous traits (AA or aa) are stable. Once the population has reached one of those end-points, the population can't drift any further. How do you know if this is happening? Unless you're lucky (unlucky?), you have to pay attention for a while. If you keep selecting for the trait you want, but half the population in each generation is always off-type (and the off-type sub-population has two types in roughly even numbers)... then you might be selecting for the heterozygous condition of some gene. In my carrots, I recognized a heterozygous color trait in the F1s (a pale-red skin color) which was indeterminate between the parents (dark-red and white skin colors) and it happened to be that I found the intermediate color far more attractive than that of either parent.
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Post by templeton on Jun 2, 2016 8:45:14 GMT -5
So I have two projects going on right now. One is TGS and the other is the Jalapeño Cross that showed up last year. The TGS I will more than likely keep everything that grows and keep general notes on the whole project. I might separate it in to different categories once the plants get to mature size. The Jalapeño Cross is in the F3 stage so I need to start thinking of ways to select and organize this project into something that can be reviewed in future. What are different ways of doing this? Also what are different ways to measure heat levels in peppers besides eating them? I was thinking of breaking the F3s into groups or families. Growing the F4s next year and then narrowing down to new varieties from there. Or should I start separating and choosing varieties this year? Any help is great. kazedwards, at the risk of over doing the explanation, if your notjalapeno in the pic was F1, then it is probably hetero at lots of genetic locations, as darren and nicolas described. If that was last year, the this year will be F2 (not F3). You will get recombinations as darren pointed out, some homo aa, some aA, some AA. The only way to tell if you have a hetero trait is to grow some more out. Some characteristics are the result of multiple genes interacting, some are single genes that are either off or on, and some are intermediate, like darren described, requiring the aA combination, (or whatever symbol is relevant in your case). Ultimately, the genetics dont really matter, if you end up with something you like (which more likely than not is not what you initially intended to aim for). That said, the way to proceed depends a bit on time, energy, and space, and how lofty your goals are. Grow as many plants as you have time to look after, and assess. You will always end up with too many choices. If you have the time, collect a few sedds from each plant, well labelled, so you can retrace your steps if needed. Without having looked into the genetics of peppers - which i recomend you do- i would collect seed from the best sized plant, the nicest heat plant, and the right wall thickness plant, and replant them. 6 of each sibling group gives about an 80% chance of at least one plant turning up in the next generation if it is a simple dominant/recessive trait. That's my usualapproach with peas, but i have limited resources. 12 plants of each sibling line gives you a bit more certainty, but 80% I reckon arent too shabby odds. Picking multiple lines to go on with would be nice, but i dont have the time or space. Once you get something with the fruit characteristics you like, you can always cross it back to another parent to introduce othrr characteristics, like yield and etc. Big breeders can do this in big trials, but with limited resources, we often need to do it in one or two steps, spread over a number of different breeding trials. Excuse tablet typos, please. t
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Post by kazedwards on Jun 2, 2016 9:49:44 GMT -5
I plan on seeing what I get and going from there. This year I have 6 plants planned and a few extras I might try to find room for.
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Post by darrenabbey on Jun 2, 2016 23:36:08 GMT -5
I plan on seeing what I get and going from there. This year I have 6 plants planned and a few extras I might try to find room for. The general rule with F2s is "The more you can grow the better". There are so many possible combinations of genes/traits, that only growing a few will greatly limit what you can see. You can grow F2s over several seasons to make more 'room' in your limited growing space.
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Post by kazedwards on Jun 3, 2016 1:20:43 GMT -5
This year it will only be 6 plants. I miscounted how many I had. Next year I plant to grow more.
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Post by reed on Jun 4, 2016 4:40:41 GMT -5
I'm growing about 20 each of my dehybridizing tomatoes and planning on saving seed from at most the two favorites of each kind. Just four of the forty. Will I be losing possibilities by discarding the other 36? Nothing I can do about it if so as even that is pushing my limits on space.
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