Maintaining hybrid vigor in an IBL

bf80255 said:

This will be a thread for serious discussion of tips, techniques and articles relating to the maintenance of hybrid vigor in inbred lines, heterosis and the polyploidy condition.

Everyone is welcome to chime in but please mention your experience level along with your comment so we dont have a bunch of know nothing assholes leaving dumb posts on here and people actually taking there advice.

Please, lets keep this civil and academic in nature. The only stupid question is the one you dont ask!

So, I came across these 2 beauties the other day and just had to share, very good article on hybrid vigor and the 2nd one mentions how they got the highest levels of heterosis by ------"The main conclusion is that the sharpest rise in yield of the F1 is manifested by crossing high yielding varieties which differ in origin and agronomic characters."

I think this has some merit to it and have considered sourcing to very unique genotypes for canni (both high yielding) and doing a little experiment. whattyu guys think?


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2821985/

http://link.springer.com/article/10.1007/BF00038966


I am particularly interested in heterosis as I am maintaining a line of autoflowers I have bred from an autoXsativa cross back to auto and am now at the F7-F8. From my understanding I should have noted a huge drop in vigor about 3-4 generations ago but as far as I can tell I have observed no such decline.

The other reason being, I know of at least 4 (tom hill and greengenes) IBLs that have been bred well past the F10 and are still producing vigorous and stunning plants. so what gives? why am I not seeing a decline? Have my choices on genetic diversity made that large an impact on such a small population size?

Greengeans has bred a line from a 1970s maui wowie cutting and maintained it past the F20 until he passed (i own a few dozen of them) and growers report extremely vigorous plants produced from his lines to this day!

What about farmers in other countries that maintain landrace strain for decades with no outcrossing? how do they maintain vigor?

I would love to hear y'all chime in and give me your opinions on these matters.

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GreenSanta said:

Thanks for starting up this thread I have been thinking the same thing for some time now. My goal with breeding is to use random males from IBLs and always use them on my best females. I am not worried about stabilizing anything at this point just create a very diverse gene pool that will eventually become narrowed down to my favorite smells and highs. The road is long. I believe the very best plants will be hidden in the most complex poly hybrids scenario. I forecast 3-5 years of goofing around and by then I should have the very best genetics that suites my needs and my liking.

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Yekke said:

Just use many moms and dads for each generation. If you enhance and maintain high genetic variance (wide gene pool) your plants will be more dominant - more vigorous.
Not that easy to smoke test big selections for multiple winners but I love it
You can check my signature for my current breeding project. Up to F4 I've used multiple parents and enhanced the gene pool as much as possible. For the F5 I will choose the most different mom and dad possible to maintain some heterosis and a stable seed lot.

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bf80255 said:

I think you are grossly undersimplifying things. "Just use many moms and dads"? are you referring to open pollination? F4 off of a cross isnt very far in I doubt youd even notice any degree of inbreeding depression if you didnt know exactly what you were looking for. Ill check it out, sounds interesting.

I would be very interested to hear from someone who has maintained an IBL past the F6 and has more than 1 line derived from the original cross (I do) I am curious as to the degree of heterosis observed in 2 lines so closely related when crossed. especially if the lines have been selected for opposing or similar traits (those are of particular interest to me) I want to know which causes the greatest increase in hybrid vigor, Im kind of leaning towards the least closely related plants producing the greatest degree of hybrid vigor based on all the scientific articles and journals ive read on the subject. but we wont know until we try it

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Yekke said:

I am talking about open pollinations with finely picked parents.
Genetic-wise, the wider your gene pool the less inbreed depression you will get. If you can combine very different genetic matter it should result in a more dominant progeny, and the less differences in genetics between the parents the more inbreed depression you will get. I doubt it gets much more complicated than that.

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GreenSanta said:

it has been many years of pollen chucking, recently i have used a male Blue City Diesel on some females. My current keeper is a ((Chemo X Respect) X Ancient OG), I used a random male from that batch of seeds to create F2s and also used it on my BCD female... down the road I will probably keep crossing those as my '' blue berry line '' while keeping the good yielders of most resinous buds with blueberry flavor. Other projects includes miss jack crosses, missjack is my Pennywise male X Senora Ampero female for a medicinal cross... eventually creating a ''medicinal line'' and a ''recreational line'', or more of each...I can already see that hybrid vigor yields great results!

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Aruanda said:

I'm new to breeding. Been studying up on it for some time. Ran across your other post with a lot of info in it (relating to BC, etc.) too.


I'm curious at this point in how to maintain IBL, or to say, how to maintain specific cultivars and how to stabilize them and continue with them indefinitely. I think you could do it the way Yekke is describing it by just allowing a large enough population and genetic crosses to happen, even if selecting multiples and you wouldn't get inbred depression or loss of vigor. I think another way is developing several 'lines' of varying phenotypes/genotypes within the population and inbreed them to stabilize the lines then every so often cross those lines to maintain vigor. Then I suppose you could then redefine the lines on any new novel traits or eek out the same lines after a few generations and repeat.

That is my speculative contribution thus far. I've been reading through several books related to the subject, specifically for cannabis. Trying to now determine some general genetic/plant breeding material that may provide more in-depth information.

It also seems that it may be less an issue than people claim it to be? As you are saying @bf80255, some farmers have been isolated for long times with the same genetic material, and certain cultivars have been maintained through line breeding for long times too.

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