# A Stab at explaining Mendel (breeding)



## Grubs (Apr 24, 2009)

I'm a pretty lit, so if this isn't coherient, just post a flame and move on.

A trait is something expressed (shown) by a plant. Color, leaf shape etc.

Each plant has 2 (or more but to keep things simple 2) genes for each trait.

So for example let's say we want to look at the color purple in plants.

Assuming there is a gene for purple buds, we can assign it a letter, like "p".

Also assuming that the same gene is responsible for the color in green buds, we can assign that a letter too, like "g".

Dominant traits are the trait that will win in a "tie". These are written in uppercase (like "G").

Ok, so let's look at a plant:

This plant has one of the following combinations (remember each plant gets 2): pp, pG, Gp, or GG. 

This is because there are only 4 ways to combine 2 different things (get a penny and a quarter and try if you want).

If the plant has purple buds we know that it has to be pp because the plant will have green buds if it is GG, or pG or GP, because remember, dominace wins ties.

So
pp = purple
Gp = green
pG = green
GG = green

So let's say our purple plant (pp) is female (sex only matters to special genes called "sex linked genes" most of the time the gene isn't).

And we breed it with a green bud plant.

The two plants are the P1 generation.

Now the tricky thing about dominate traits is that we can't tell if the plant is GG, pG, or Gp, because of it winning ties.

Each offspring gets one gene from each parent. One from the purple plant, and one from the green

If we cross our pp with a green plant it will be an F1 which might be one of four combinations:

pp x GG (both plants breed true for this trait):

Since they take one from each parent, they will all be pG. All the combinations you can make with one out of pp, and one out of GG, all wind up being pG. 
The four combinations are:
pG
pG
pG
pG

Get 2 pennies and 2 quarters if you want to prove it. It helps to put one heads up and the other tails up in each pair.

So all of the offspring will be green buded. 

But if the green plant was pG instead of GG it would be:

pp x pG

Since mom will always give a p no matter what, we know the first gene will always be a p. Dad could give a p, or Dad could give a G.

So our combinations are:

pp = purple buds
pG = green buds
pp = purple buds
pG = green buds

So half will be green, and the other half purple.

If dad were Gp, you would have the same result as if it were pG.

To get something to breed true, you work toward getting pp. Which when crossed with another pp will always produce purple buds. Or GG, which when crossed with another GG will always produce green buds.

Breeding is trying to get the desired combinations expressing themselves in the same plant.

A less scientific, but longer used method is just to always breed the best male to the best female.

And yes, you can see improvements if you are patient.

This is just a basic first stab, but it is the part you have to get before the rest makes any sense. 

Hopefully it will help someone get a little closer to understanding.


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## Grubs (Apr 24, 2009)

If we cross our pp with a green plant it will be an F1 which might be one of THREE combinations:

sorry, my bad.


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## Da Chef (Apr 25, 2009)

if i remember highschool biology correctly than this is all true, but i remember there being more to it in someway. i also remember using some kind of square diagram that helps you figure out what will happen with the offspring of the parents. (minutes later) just looked it up. it's called a mendelian square. i havn't gotten much into breeding, in fact i have no clue about breeding. but i will post some links about mendelian breeding techniques that i found searching google.
http://www.ndsu.nodak.edu/instruct/mcclean/plsc431/mendel/mendel1.htm
http://www.teachersdomain.org/resource/hew06.sci.life.gen.mendelinherit/
http://www.pc.vccs.edu/biology-labmanual/lab8mengen/mendelgenetics.htm

some of this stuff gets intense and i dont know how practical it is for people on this board.
but im sure if you are starting your own breeds you must have a basic understandig of mendels theories.


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## Grubs (Apr 25, 2009)

Da Chef said:


> if i remember highschool biology correctly than this is all true, but i remember there being more to it in someway. i also remember using some kind of square diagram that helps you figure out what will happen with the offspring of the parents.


The square is a way to show the combinations.
.....p......p
p...pp....pp
G...pG...pG

Of course there is a bit more to it all, but it mostly just extends these basics.


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## RandomKindness (Apr 25, 2009)

frequencies is whats really useful, of course we are limited in the population we can control(well most of us anyway!) so its hard to make education selections

as dj short says - the end product is all hes after, after high/stone he looks at taste/aroma then everything else comes into play


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## Grubs (Apr 25, 2009)

RandomKindness said:


> frequencies is whats really useful, of course we are limited in the population we can control(well most of us anyway!) so its hard to make education selections
> 
> as dj short says - the end product is all hes after, after high/stone he looks at taste/aroma then everything else comes into play


Right, if you understand the basics of how it works, you start getting a feel for sorta what to expect, and what to cross with what to give you the best chance of getting what you want.


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## born2killspam (Apr 25, 2009)

You aren't really using standard lettering conventions is your description.. You're mixing traits.. For instance if the trait is purple buds, the 1:2:1 possibilities could be listed of as PP Pp pP pp, where the capital denotes the dominant allele.. So PP, Pp, and pP will express the same.. Its also customary to letter by dominance, so if in that example purple only expressed with pp, then it would be better to swap all P/p's for G/g's, then only gg would express purple..


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## Grubs (Apr 25, 2009)

It is true that the style you described is generally used when you are dealing with known dominate and recessive traits, where you can look them up in a book.

However, the style I have described is what is commonly used when you are still trying to DISCOVER the dominate and resessive traits. It is used a fair amount, it isn't something I just made up. I think it is also easier to follow for people who don't have any background in genetics. It is simple enough to convert if you need to for a test.

I'm not saying that born2kill is wrong, I'm just saying that we are both right in our own way. Born2kill obviously understands the concepts behind what I am trying to explain.

Use whatever works for you.


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## Grubs (Apr 25, 2009)

Speaking of which. Does anyone know anyplace to look up or find out the dominate/resessive/single gene/multi gene/sex linked alleles for marijuana? Or does everyone just keep thier own notes?


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## Da Chef (Apr 27, 2009)

sounds like youre getting into industry secrets!! that would be pretty cool though. 
a comprehensive list of marijuana alleles pertaining to THC, potency, flower weight, flower size, color, etc... pretty sweet if you could maximize your own strains yourself from seeds you buy from seed banks. 
but i guess that is the whole concept of breeding anyway.


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## Grubs (Apr 27, 2009)

Well, we got growers here, and I am sure a few hobby breeders. If we weren't a bunch of stoners we could put our results on a wiki kind of thing. Have a huge chunk mapped out in no time.


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## MEANGREEN69 (Apr 27, 2009)

yeah i love breeding cannabis...hey grubs are u breeding anything right now?? i got some auto ak47Xhindukush X one of my indica's and 2 satvias...also breeding some purps with a nice plant i got (i wont say)...also going to breed some og thai hazeXsunk#1 but just going to add touches to it nothing major...MEANGREEN..


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## CaGeD (Apr 28, 2009)

"stacking traits" for expression.


Good thread.

I have always said that weed strains need pedigrees.


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## McNea (Apr 28, 2009)

it's called a pugnent square, and i have a biotechnology degree, and if anyone needs some explanations i got all the answers


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## bicycle racer (Apr 28, 2009)

i always watch the breeding threads my favorite


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## born2killspam (Apr 28, 2009)

McNea said:


> it's called a pugnent square, and i have a biotechnology degree, and if anyone needs some explanations i got all the answers


You mean Punnett square??


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## Ghost420 (Apr 28, 2009)

we dont know how the cannabis species reproductive system works. what i am try to say is that peas are complete dominant plants.(yes thats right Mendel got lucky and had a good scientific model) we dont know cannabis heritability works. 

there are so many phenotypes to play in a situation like this. the punnit square is simply not fit for cannabis breeding


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## Grubs (Apr 28, 2009)

Although completely mapping out marijuana is a very daunting task, and at least some of the desired traits are likely to be complex and multi-gened, but there are really only a good sized handful of traits we really care about. BUT, dogs, cats, cattle, chickens, pigs, corn, wheat, and others were successfully improved well before people had much of a grasp on the mechanics of genetics. You don't have to be a geneticist to make progress, you just need to know what to look for, get a little lucky, and know how to capitalize on successes. 

While it may be true that some "breeders" just got really lucky, there must be many more (many of which never make it out of the growers "circle") that have some great information they could share. Not everyone is into it for the $$. I am about a year into a NLxBB strain I want to use as a base for other things. It's going to take at least another year (if I am lucky) just to get it into ok shape (I hope). Even knowing a couple of ressessive traits would be a huge help. When I figure any out (still not 100%, or even 80% sure). I'm going to post them all over.

Ok, in the interest of those who might want to know: Here is what I do to help with my recordkeeping (lotsa labels).

Date seed or clone started. 
Male, female, or ?. While it might be obvious in flowering, while vegging I really don't want to scrog a boy. 
Generation from original seeds P1,F1,F2,F3... 
Strains of the P1 ancestors, with percentages if not 50-50
Number sets to ID a mother and all clones. When I find something I like, I want to know where they all are.

As if that wasn't enough labeling, there are the award stickers. Yup, I give my babies awards. IF I can find one that deserves one. 
For awards, all clones of the plant are treated as the same plant.

The best plant in veg gets an award.
The best plant in flower 
The best taste
The best color (iffy on this one, might just ignore until I can get lavender or blackberry, so far no color to judge)
The best potency
The best trics.

But Grubs, you ask, a bunch of those awards are for things that are after harvest. What good does it do you then?

Because remember what I said about numbering mom & clones, when I harvest I put the same number on the jar. If I light up and find something I dig, I look at the number and go back and give the award to the clones (same plant) still in veg. If it isn't special, those are the ones to go when I want space for a "better" plant, or just outright killed off.

That really isn't all that hard, and I am sure someone here knows a better method, but you could do most of that without understanding much about genetics. And if you take the time to learn a little about it, you can make even better guesses.

On the other hand, keep in mind that my best accomlishment so far with this is to make male that's freakin awesome. Dude could run down to the park and buy for you, if it were a female I'd have to change my pants. But I like the plants I have now, better than the plants I started with (and I know 'cuz I am bonzi-ing a couple of the original P1s), and that's enough to keep me futzing with it.


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## Grubs (Apr 28, 2009)

I probabbly should have mentioned that breeding decisions are based on the awards, just to make sure that was clear.


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## bicycle racer (Apr 29, 2009)

a good cross is often more than the sum of its parts. hybrid vigor it seems most strains are inbred crossing revitalizes the gene pool. f-1s grow better than either parent in my experience as long as of relatively different lineage.


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## Grubs (Apr 29, 2009)

Correct Racer, that's why a good strategy is to stabilize two different strains, and then cross them for the hybrid vigor. F1 hybrids also are very similar to each other. If one is AA and the other aa, then all the F1s will all be Aa for that triat, since they have to take one from mom and one from dad. this is part of why F1s are desirable for growing. For breeding on the other hand, AA or aa is preferable, because the results are easier to manipulate.


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## bicycle racer (Apr 29, 2009)

if cloning you can sometimes find the winner in the first batch of f-1's you have made. when i do i cross to a known winner of clone only genetics in which case someone has also picked a favorite for mainstream use. it is in a way cheating but my space is limited so if i can use a strain already tested for its general attributes and stability i will some great strains can be produced this way in my experience.


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## MEANGREEN69 (Apr 29, 2009)

bicycle racer said:


> if cloning you can sometimes find the winner in the first batch of f-1's you have made. when i do i cross to a known winner of clone only genetics in which case someone has also picked a favorite for mainstream use. it is in a way cheating but my space is limited so if i can use a strain already tested for its general attributes and stability i will some great strains can be produced this way in my experience.


theres no cheating in breeding my brother..the early bird gets the worm...yeah a real easy way to make a strain is to get two known genetics of the same type (I.E indica or satvia) that are ture breeding and stalbe and cross them in a IBL program....MEANGREEN.


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## bicycle racer (Apr 29, 2009)

wait what???????


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## born2killspam (Apr 29, 2009)

A 'winner' is merely a good candidate for breeding.. It carries no promises since A+B <> (A+B).. I agree there is no cheating in breeding, but cloning does allow you to work with the past in a way, and hind-sight is 20/20..
I stress again that the cloning only allows you continued access to a good 'candidate' for hybridization.. Results from the cross may not be what you expected at all, or even more likely they won't be anything near uniform since it takes two damn true breeding parents to acheive that..
That being said, hybrid vigor is real, and its quite likely you end up with an assortment of strong phenos simply by crossing two good parents regardless of what you know about their genotypes..


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## LightGrower (Apr 29, 2009)

The problem is that breeding isn't as easy as Mendelian genetics. More often than not genes are linked. In a Mendelian system each trait is controlled by one gene and the genes are independent, segregation of one from another. Usually traits are linked to several different genes, each gene can control more than one trait, and there can be physical linkage. Then recombinance throws a wrench in.

Simply put if you crossed a plant dominant purple recessive low thc with a plant recessive green and dominant high thc; you wouldn't necessarily get a purple high thc plant. And this is a real basic down and dirty example. Breeding class makes the brain hurt.


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## Grubs (Apr 30, 2009)

LightGrower said:


> The problem is that breeding isn't as easy as Mendelian genetics... .


Oh true enough. But look at a wolf, then look at a chihuahua, and tell me again it's too hard for amatures to make progress to bother with.


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## Grubs (Apr 30, 2009)

Simply put if you crossed a plant dominant purple recessive low thc with a plant recessive green and dominant high thc; you wouldn't necessarily get a purple high thc plant. 

Ok, so you are decribing
P?tt x ppT? where P is color and T is thc

So we expect to get

...........Pt..........Pt..........?t..........?t
pT...pPTt........pPTt......p?Tt........p?Tt
p?...pP?t........pP?t......p??t........p??t
pT...pPTt........pPTt......p?Tt........p?Tt
p?...pP?t........pP?t......p??t........p??t

Out of the sixteen possibilities, we are only interested in PpTt (4) for sure, and maybe more depending on the values for ?. We might get lucky or not.

So we know that about 25% will likely be what we are looking for, and plant enough to have fair odds of it showing.

You would know you shouldn't have to grow thousands of plants to find the combination once. 

Also keep in mind that it's the number of seeds used from a single generation, you can do 4 grows of 25 and get the same results as if you grew 100 at the same time.

If I am off in my calculation, I'm buzzed, post a correction for everyone else's benifit, and get over it.

Are there exceptions? You bet. Does it require luck? Yuppers. Are some combinations impossible? Likely. But I refuse to buy that the only people who can do this is some secret society of corporate breeders who use magicial powers to alter the genetics. Well, until they start gene splicing and such.

I mean absolutley no disrespect towards commercial breeders. that's a job I'd do a donkey for.


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## born2killspam (Apr 30, 2009)

You need a large selection because you can't 'really' boil it down to those permutations..
You might have (P1P2)?(t1t2)x(p1p2)(T1T2)? or any scarily complex recipe where traits are controlled by many unlocked alleles.. Sure there are broader Punnet squares, but no matter how deep you go, you'll never truly know the genotypes, and the more plants you'll need to observe to spot inconsistencies in your model..


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## Grubs (Apr 30, 2009)

born2killspam said:


> You need a large selection because you can't 'really' boil it down to those permutations..
> You might have (P1P2)?(t1t2)x(p1p2)(T1T2)? or any scarily complex recipe where traits are controlled by many unlocked alleles.. Sure there are broader Punnet squares, but no matter how deep you go, you'll never truly know the genotypes, and the more plants you'll need to observe to spot inconsistencies in your model..


You are correct, but that is no reason not to try, and Punnet squares will give you more informed guesses than just randomly mating plants and not having any clue how to interpret the results.

Simply breeding your best to your best will generally give better results than just mating any two random plants in your collection.

Some people like to just buy good seeds and then take clones from the seeds, that's cool. I'm just putting in my 2 cents for those interested in mucking about with breeding.


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## born2killspam (Apr 30, 2009)

It just seems that you're more bound/determined to make the results meet the model than the other way around.. Breeding, and the scientific method really go hand in hand..


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## Grubs (Apr 30, 2009)

Naw, I view it a lot like playing poker, the better you understand your odds and the way the game is played, the better off you are in the long run.


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## born2killspam (Apr 30, 2009)

As long as you remember that there are more correct/complicated methods of calculating odds than the simple calculations ppl use at the table..


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## Grubs (Apr 30, 2009)

born2killspam said:


> As long as you remember that there are more correct/complicated methods of calculating odds than the simple calculations ppl use at the table..


So spread the wealth, enlighten us.


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## born2killspam (Apr 30, 2009)

Most ppl only calculate the odds that they hit a hand using the rule of 4 & 2.. That doesn't necessarily correlate to winning the hand for instance.. Just an example, there are many others depending on the situation at hand..


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## Grubs (Apr 30, 2009)

born2killspam said:


> Just an example, there are many others depending on the situation at hand..


I meant do you have anything to contribute about how to wind up with cool plants.


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## born2killspam (Apr 30, 2009)

As far as breeding goes, I know the theory.. The theory itself is pretty simple to me since I've probably spent a couple thousand hours grinding through statistical physics..
What isn't simple is the feasibility of accurately determining genotype of a hybrid strain by assuming a simple Punnet square, and the number of plants needed to test a more complex square grows exponentially..
The Punnet square is more feasible if you define your properties on the basis of your F2s or later, after the initial crosses.. That way you'll have cancelled out alot of codominance factors, and simply accepted the codominant property, and observed new properties unlike either P1.. Hybridizing opens up a Pandora's box of recessive genes that have been pummeled down within its own IBL, but become dominant when put with others.. The closer you want to get to picking/choosing combinations of traits pure to the P1's, the more selection you'll need.. The more you inbreed your cross before defining your Punnet square, the better your chances of locking down properties you've defined in your square with a smaller number of plants..


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## $toned che$$ (Apr 30, 2009)

This really brings me back to sophomore biology, but it's keeping my attention better this time through cuz we're applying it to weed xD


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## MEANGREEN69 (May 3, 2009)

it all comes down to crossing and breeding IN REAL LIFE! u can try and say this will happen and that will happen...but unless you REALLY DO IT..it dont mean shit! plants can do some crazy stuff.nothing is for sure on paper/screen..bottom line: just use the math with some REAL LIFE crossing find out what works and share....peace....MEANGREEN.


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## Grubs (May 6, 2009)

So does anyone know the dominate ressessive for any trait.

I've read on boards that purple color and autoflowering are both recessive, but clue if that is accurate or not.


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## MEANGREEN69 (May 6, 2009)

Grubs said:


> So does anyone know the dominate ressessive for any trait.
> 
> I've read on boards that purple color and autoflowering are both recessive, but clue if that is accurate or not.


i heard that autoflowering is recessive....i wonder if flowering times from satvia's are dom or ress compeared to an indica or vise versa??? or is that a trait that can be ether depending on the individual plant/s????/


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## Grubs (May 14, 2009)

From 420 magazine

Purple Cannabis
However, purpling is as natural as the changing colors on the leaves of deciduous trees in autumn, which is attributed in part to the pigment anthocyanin. Anthocyanin expression is controlled by both genetic and environmental factors. Purpling is a simple dominant Mendelian trait, with quantitative expression.


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