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View Full Version : Selecting Breeding Individuals by MrSoul


Dobie
03-08-2006, 02:43 PM
[Verbatim as posted on the internet by "Cindy 99's" originator "MrSoul" back in December of 1999...]

"Selecting Breeding Individuals for Marijuana Production:

Breeding fine cannabis involves carefully choosing the breeding stock.
To choose wisely we must first define male and female cannabis:

Female Cannabis – The female cannabis plant, unlike the male, is grown to produce marijuana. Premium marijuana is produced in seedless form by eliminating all pollen sources from the growing environment. Seed production reduces the value of marijuana dramatically by lowering the yield and potency of the flowers. Hermaphrodites are plants expressing both male and female flowers. They may fool a grower who mistakes the "hermie" for a female - only to find his crop is ruined by the unexpected release of pollen. Knowledgeable marijuana breeders are very careful to avoid hermaphrodism in their seedlines.

The attributes of a valuable female are the following (in descending order of importance):

1. Resistance to hermaphrodism
2. Vigor/Yield
3. Potency
4. Flavor
5. Rate of flowering response
6. Resin production
7. Stature
8. Scent
9. Floral structure
10. Floral color


Male Cannabis – The male cannabis plant is essentially only useful for breeding. The male plant makes very poor marijuana, being mostly leaves without the dense resinous floral clusters of the female the yield is miserable. More importantly, the male of the species has virtually no potency in comparison to that of female cannabis. The males do carry genes that influence the expression of ALL the traits listed above, but not many of them are directly observable in the male itself due to the male phenotype being markedly different from the female phenotype. A male cannabis plant’s value is DEFINED by the quality of his daughters.

Naturally, when starting out with a large number of potential breeding individuals, one desires to “weed out” the undesirable individuals.

The female is easy to evaluate because all the traits favoring marijuana production are directly observable in the female. It's a simple matter of growing & flowering the females to grade their performance and smoking the resulting marijuana. The breeder then chooses only those females most closely matching the breeder's personal ideal to be used as seed parents.

The directly observable & important traits of male cannabis are as follows:

1. Resistance to hermaphrodism
2. Vigor
3. Stature
4. Maturation rate

All males expressing poor quality in any of these traits should be culled so as not to pass the weak trait on to the progeny.

Males are also be observed to have a certain scent and floral structure but the importance of these traits pale in comparison to those listed.

The potency of male plants, and especially the potency difference between individual males in a group, is generally too subtle to be measured by anything short of professional scientific laboratory equipment. Moreover, there is no conclusive proof that the most potent male in a group actually creates the most potent female progeny, although it seems intuitive that that should be the case. The difficulty of determining a male plant's potency is a major hurdle to proving this link.

Thankfully, logic dictates that the potency of a male plant ITSELF isn’t very important, as we aren’t interested in growing males for marijuana production. The value of a male lies entirely in the traits he consistently passes on to his daughters. Therefore it’s unnecessary to identify the one male amongst a group of potential pollen donors with the greatest potency. It’s far more logical to evaluate the female progeny of each male to define the potency of each male in the group.

Male cannabis individuals may be graded for quality by a controlled pollination of IDENTICAL female clones (one for each pollen donor). This isolates the influence of the male by holding CONSTANT the influence of the female on each cross. The seeds resulting from each clone are then grown and the progeny is graded to determine which of the crosses was the most successful. When the group with the most desirable female progeny is identified, the responsible male has been identified as the most valuable. Males can be kept in the vegetative state exactly like female “mother plants”, except that we should call them “dads” of course. Clones from the favored male can be flowered as needed along with the breeding female(s) when seeds are desired.

Due to the clandestine nature of marijuana growing, in most cases there will only be about 10 males to be evaluated after culling all those with directly observable defects. Breeding with larger populations is always preferable, as genetics is a statistical "game".

Commercial breeders would clearly benefit from the development of a reliable method of identifying males with the greatest potential for passing on high potency genes. Perhaps someone will do the necessary research someday, but by following the above method, growers can accurately pin-point the ONE male in their small group which is the most potent...in the only meaningful sense of “male potency”. "

MrSoul
{"8^)_~

suzy cremecheese
03-10-2006, 02:28 AM
Thanks Dobie.

Cuzin_Dave
04-26-2006, 07:25 AM
A person would be pretty hard pressed to find any chapters on "cubing" in a book on plant breeding or genetics. Back crosses in the standard plant breeding sense are used to reinforce pre potent traits from the parental lines and presumably increase the probability and frequency of certain phenotypes and genotypes in future populations. Cubing in theory at least uses the female select clone to retransmit her desirable traits and reinforce characteristics through her male offspring. Thus cubing math goes .50, .75, .88, .94, .97, .99.
Here is the arithmetic way of calculating:
Each of the P1 Parents contribute .5 or 50% of the genetic contribution.
F1 = .50 + 0 = .50
F2 = .50 + (50 * 1/2) = P75
F3 = .75 + (50 * 1/4) = P88
F4 = .88 + (50 * 1/8) = P94
F5 = .94 + (50 * 1/16) = P97
F6 = .97 + (50 * 1/32) = C99
The idea behind cubing is simple and elegant, although it completely ignores such things as the independent assortment of phenotypes, discrete random probability, effective breeding populations, dominant/recessive ratios and expected breeding values and so on.
Back crossing usually involves repeated use of one the P1 parents as the ideal phenotype/genotype. The idea is that parental traits will be retained and reinforced through repeated back crossing. Normally in small populations there is the real potential for genetic drift (sampling error) simply based on random unsystematic changes in gene frequencies, so in back crossing there is an attempt made to increase the frequency of desirable parental genes without having to grow larger populations and make recurrent trait selections.

Cuzin_Dave
04-26-2006, 07:41 AM
People have to understand that Soul's cubing arithmetic was based on simple genetic contribution. For example take 2^10 or 1024. After 10 generations an individual P1 parent would be contributing 1/1024 th of the genetic material.
Cubing math is not based on any genetic theoretical foundation as such. Actual inbreeding coefficients are calculated based on the effective breeding population and changes in the effective breeding population from generation to generation . Back crossing will reduce the inbreeding coefficient. The rate of inbreeding will also depend on the Expected breeding values of the selected parents as some will have higher breeding values than others.
Let's take a hypothetical example:
Breeder X grows out 20 plants and gets 6 males and 14 females.
Effective breeding population will be:
(4)*(6)M*(14)F / 20 Plants Total =16.8

Change in inbreeding per generation:
1 / (2)*(16.8)= 2.9%

The "best" effective size calculation in this example:
16.8/20 = 84%
Cubing was a method of dealing with low effective breeding populations totally predicated on the idea that the Mother plants act as transmission belts of half the genetic information to each subsequent generation. It does not factor in phenomena like the laws of independent assortment into separate phenotypes.

Schip
05-22-2006, 07:42 PM
Effective population size is one of the most overlooked concepts in plant breeding, especially of cannabis. I think people get stuck on these simplistic models where AA x aa = Aa, but that ignores the fact that in wild populations, there is not just A and a, but also B and b and C and c and D and d etc... all possible combinations of which might be beneficial in some different environment. So if you cross two plants, you have at most 4 alleles for each gene, but a healthy wild population will have 15, 20, or maybe even 200 different versions of each gene, which allows the population to respond to changing weather conditions, etc. The take-home message is that you need an Ne = 20 or more to avoid inbreeding depression over several generations. This is true for a wide variety of crops, although some research indicates that hemp is more tolerant of inbreeding than alfalfa, onions, corn, etc.

One thing, the statement "The effective breeding population can never be larger than the number of males selected for breeding." is incorrect, Ne can never be larger than the number of males times 4... or whatever the less-abundant gender is.

country boy
05-22-2006, 10:17 PM
Curious: how many folks can do the large outdoor grows mentioned to get the out crossings needed?
i recall that most, if not all, crosses happen in a room/closet (without UV added).
are we looking for a production mother or keeping the gene pool 'pure'?
The peanut gallery, rarely cares about 'outdoor' viabliity...especially since most produce is produced indoors...
i'm sure UV radiation(Vic's micro mix) is a real variable but, reality steps in...
cull ruthlessly, in search of viable moms and deal with what you've got...
move a plant from it's 'natural' environment, and all bets are off...

c-ray
05-22-2006, 10:47 PM
the effective breeding population model is an ideal...
ultimately all cannabis will adapt to it's situation of the moment given a specific selection pressure...though it is important to maintain a sense of balance in it all, and using more than one male in a cross is a good start...we are not perfect but we need to use some common sense

Cuzin_Dave
05-23-2006, 12:20 AM
Effective breeding populations Ne have a profund impact on the level genetic diversity of a given population. Genetic drift is most pronounced the smaller Ne becomes. Another term used would be sampling error from statistics. An example would be flipping a coin. Over an infinite number the probablity of heads or tails would be 50/50. But over maybe 5-10 flips of the coin there could be a vastly different combination of outcomes and frequencies. The genetics of small populations are much the same. Selections based on small sample sizes can show very radical and unsystematic shifts in the frequencies of certain alleles. These radical shifts are compounded if the sample size remains small and the selected population continues to inbreed.

hydrorascal
05-23-2006, 01:19 AM
I am not a breeder. However....toooo many are afraid to ever even attempt selective pollinization. With the current state of affairs, more of us need to not only learn how to .. but to actually do it.~!~

For the small time folks...common sense is a real key. Of 10 seeds popped, 3 popped up as males. Choosing a pollen donor was simple. One grew faster, much better branch structure, had aggressive roots and standing back looking at the 3 just flat looked better. 2 were culled and the donor selectively pollinated the best looking of his sisters.

The resultant seeds were larger than the originals, darker brown with deeper colored stripes. 3 of them were germed, all popped and proved to be very healthy females. Even only having pollinated 4 bud sites, over 50 very viable seeds were produced.

Cuzin_Dave
05-25-2006, 07:38 AM
The great love affair with sprinkling donor pollen on a selected unstable poly hybrid clone most likely will continue for the foreseeable future and virtually no amount of scientific argumentation to the contrary will change this meme.
There are methods for estimating the probability of genetic drift and underscoring its devastating impact on unsystematic shifts in allele frequencies where Ne is small.
The formula is: Prob. = (1 - frequency) ^ 2 ^ Ne
For example, lets say there is a less common allele (w) in a white widow clone that occurs say 5% of the time (.05) and further for arguments sake Ne = 2.
So. (1.- .05) = .95
(.95) ^ (2)(2) = 81.4% probability of elimination
Make Ne = 50
(.95) ^ (2)(50) = .00592 probability of elimination.
As is the case with any algorithm, the answers will change depending upon what numbers one intends to plug into the formula.
The higher the frequency of an allele in a given population the greater its likelihood of surviving a genetic bottleneck with the opposite being true of lower frequency alleles surviving when Ne is very small.