The Cannabis Breeder's Bible (9 page)

Eventually you will have your Silver Kush strain but only with the four genotypes that you wanted to keep. You may still have a variety of non-uniform plants in the group. Some may have purple stems, while others may have green stems. Some may be very potent and others not so potent. By constantly selecting for desired traits you could theoretically manipulate the strain into a true breeding strain for every phenotype. However, it is extremely unlikely that anyone will ever create a 100% true breeding strain for every single phenotype. Such a strain would be called a perfect IBL. If you’re able to lock down 90% of the plant’s phenotypes in a population then you can claim that your plant is an IBL.

The core idea behind the true breeding technique is to find what is known as a donor plant. A donor plant is one that contains a true breeding trait (homozygous, preferably dominant for that trait). The more locked down traits are homozygous dominant the better your chances of developing an IBL, which does not mean that the line of genetics will be true breeding for every trait, but rather that the strain is very uniform in growth for a high percentage of phenotypes.

Some additional advanced breeding techniques that will help you to reduce or promote a trait in a population are discussed below. Using these techniques may not create a plant that is true breeding for the selected traits, but it will certainly help to make the population more uniform for that trait.

ADVANCED BREEDING TECHNIQUES

Simple Backcrossing

Our first cross between the Master Kush plant and the Silver Haze is known as the F1 hybrid cross. Let’s pretend that both traits are homozygous for leaf color: the Silver Haze is pale green and the Master Kush is dark green. Which is SS or ss? We won’t know until we see the offspring.

This F1 cross will result in hybrid seeds. Since S is dominant over s, we’ll know which color is more dominant and from which parent it came from. In this example, the overall results are pale green. Thus, the pale-green allele is dominant over the dark-green.

S = Silver Haze pale-green leaf trait is dominant
s = Master Kush dark-green leaf trait is recessive

We also know that because no variations occurred in the population, both parents were homozygous for that trait. However, all the offspring are heterozygous. Here is where we can take a shortcut in manipulating the gene pool for that population. By cloning the parent plant SS, we can use this clone in our cross with the Ss offspring. This is known as a backcross. Obviously, if our parent is female then we’ll have to use males from the Ss selection in our backcross, and vice versa.

Now our first backcross will result in 50% homozygous (SS) offspring and 50% heterozygous offspring (Ss) for that trait. Here all the offspring will exhibit the pale-green leaf trait. If we didn’t backcross but just used the heterozygous offspring for the breeding program we would have ended up with 25% homozygous dominant (SS), 50% heterozygous (Ss) and 25% homozygous recessive (ss), as shown below.

Backcrossing seriously helps to control the frequencies of a specific trait in the offspring. The F2 hybrid cross produced some plants with the dark-green leaf trait. The F2 backcross did not.

The F2 backcross above is an example of simple backcrossing. Let’s see what happens when we do our second backcross (F3) using the same original parent kept alive through cloning. Our second backcross is referred to as
squaring.
Since we’re dealing with only two types of offspring Ss and SS, we’ll either repeat the results of the F2 backcross…

…or we will successfully lock down the desired trait as follows:

In the F3 backcross with the homozygote, all of the offspring are homozygous dominant (SS) and thus true breeding for that trait.These offspring are the result of squaring and can never produce the ss traits because the SS trait is now true breeding and stable. The F3 backcross with the heterozygote has some Ss offspring. If we breed the Ss and Ss offspring we can produce the ss trait. This line would not be stable.

HOW TO GENERATE A CLONE MOTHER

The best way to generate a clone mother is to grow a large population of plants from the same strain. If the strain is an IBL then you should find that the plants do not exhibit much variation. It can be difficult to find a clone mother from an IBL strain, though, because IBLs are created to provide a population of plants from seed from the F3 Backcross with the homozygote, which all resemble the clone mother that the breeder enjoyed and wanted to share with you.

The best way to generate a clone mother is to select her from a large population of F1 hybrids. If you do not find a clone mother in the F1 population then allow random mating to occur and see if you can generate a good clone mother in the F2 population. If you do not find the clone mother in the F2 population then either grow a larger population or select different parents to create a new F1 population.

A clone mother is only as good as the environment she is grown in. The environment influences how the genotype is displayed in the phenotype. Although indoor plants can grow outdoors and outdoor plants can grow indoors, the expressed phenotype of the genotype may change because of the diversity in growing conditions. This is why breeders urge that you grow their strains in the recommended environment.

Selfing

Selfing is the ability of a plant to produce seeds without the aid of another plant and refers to hermaphrodite plants that are able to self-pollinate. Hermaphrodite plants have both male and female flowers.This usually means that the hermaphrodite plant is monoecious. Most plants are dioecious and have male and female flowers on separate plants.

Monoecious cannabis strains will always display both sexes regardless of the growing conditions. Under optimal growing conditions a monoecious cannabis strain will still produce both male and female flowers on the same plant. Under optimal growing conditions a dioecious cannabis strain will produce male and female flowers on separate plants.

Stressful growing conditions can cause some dioecious cannabis strains to produce both male and female flowers on the same plant. Manipulating an irregular photoperiod during the flowering stage is an easy way to encourage the dioecious hermaphrodite condition. Not all dioecious cannabis strains can become hermaphrodites. The dioecious cannabis strain must have a preexisting genetic disposition to become hermaphrodite under stressful conditions in order for male and female flowers to appear on the same plant.

If you find a dioecious cannabis strain that has the hermaphrodite condition you can separate this plant from the rest and allow selfing to occur. If the male pollen is viable on this plant then the hermaphrodite will produce seeds. Selfed plants that produce seeds will eventually generate offspring that:

1. Are all female

2. Are all hermaphrodite

3. Produce male, female and hermaphrodite plants because the environment also influences the final sexual expression of the selfed plant

4. Express limited variation from the original selfed plant

Breeders should note that it is nearly impossible for a hermaphrodite to create male plants although environment can influence males to appear. Hermaphrodites usually create female-only and hermaphrodite seeds. The female-only seeds often carry the hermaphrodite trait. Selfing has become popular among those who wish to breed all-female or feminized seeds. Unfortunately feminized seeds do very little for the cannabis gene pool as the hermaphrodite condition prevents growers from generating a sinsemilla crop.

Well-informed breeders tend to shy away from producing feminized seeds. Feminized seeds should only be used for bud production and not for breeding. Generating seeds from feminized plants is only advised for personal use and not for distribution.

NOTES ON SELFING BY VIC HIGH

[These notes were taken from an online interview and provided by Vic High, BCGA breeder.]

100 % Female Seeds

Posted by The Silicon Magician on February 13, 1999 at 05:17:41 PST

As some of you may know I’ve been a regular in the chat room for a while and I spend a large amount of time in there. I have had the extreme pleasure of speaking to Mr. XX over the last few nights for many hours and have gotten to know him quite well via email and the chat. He has confided in me and in a few others about his process for coming up with 100 % female seeds.

Mr. XX is a very nice guy, funny too and it’s always a pleasure to speak with him. He doesn’t speak English too well, but his wit comes through the rough language and he’s a riot. He’s a pure lover of cannabis and feels that everyone should share and share alike. He simply wants to share his knowledge with the cannabis community, and because he’s spent 15 years researching this, I spoke about it with him in depth.

He has stressed literally hundreds of plants with irregular photoperiods. What he does is put the lights on 12/12 for 10 days. Then he turns the lights on 24 hours, then 12/12 again for a few days, then back to 24 hours for a day, then 12/12 again for a few weeks. If he does this and no hermaphrodites come up, he has found a 100 % XX female that can’t turn hermaphrodite naturally. He claims that your chance of finding a 100 % XX female is vastly increased when using Indica genetics. He also informed me that the more Afghani or Nepalese genetics the plant has, the better the chances of finding a natural XX female. In his own words: “Where did nature give weed a home originally?” I tried to get him to narrow it down to a ratio, but he never specified just how many plants per are XX females. He claims there are plenty of XX females for everybody, and that’s all he will say on the subject. It takes a lot of time and a lot of plants to find that one female.