Growing Marijuana (Growing Cannabis)
HOW TO TRUE BREED A STRAIN
Breeding and growing cannabis (growing marijuana) strains is all about manipulating gene frequencies.
Most strains sold by reputable breeders through seed banks are very uniform
in growth. This means that the breeder has attempted to lock certain genes
down so that the genotypes of those traits are homozygous.
Imagine that a breeder has two strains: Master Kush and Silver Haze.
The breeder lists a few traits that they particularly like (denoted by
*).
This means they want to create a plant that is homozygous for the following
traits and call it something like Silver Kush.
Silver Kush
Pale green leaf Hashy smell Silver flowers Short plants
All the genetics needed are contained in the gene pools for Master Kush
and Silver Haze.The breeder could simply mix both populations and hope
for the best or try to save time, space and money by calculating the genotype
for each trait and using the results to create an IBL.
The first thing the breeder must do is to understand the genotype of
each trait that will be featured in ideal "Silver Kush" strain.
In order to do this the genotype of each parent strain for that same trait
must be understood. Since there are four traits that the breeder is trying
to isolate, and 4x2 = 8, eight alleles make up the genotypes for these
phenotype expressions and must be made known to the breeder.
Let's take the pale green leaf of the Silver Haze for starters. The breeder
will grow out as many Silver Haze plants as possible, noting if any plants
in the population display other leaf colors. If they do not, the breeder
can assume that the trait is either homozygous dominant (SS) or recessive
(ss). If other leaf colors appear within the population, the breeder must
assume that the trait is heterozygous (Ss) and must be locked down through
selective breeding. Let's look closely at the parents for a moment.
If both parents were SS there wouldn't be any variation in the population
for this trait. It would already be locked-down and would always breed
true without any variations.
With one SS parent and one Ss parent, the breeder would produce a 50:50
population — one group being homozygous (SS) and the other heterozygous
(Ss).
If both parents were Ss, the breeder would have 25 percent SS, 50 percent
Ss and 25 percent ss. Even though gene frequencies can be predicted, the
breeder will not know with certainty whether the pale green leaf trait
is dominant or recessive until they perform a test cross. By running several
test crosses the breeder can isolate the plant that is either SS or ss
and eliminate any Ss from the group. Once the genotype has been isolated
and the population reduced to contain only plants with the same genotype,
the breeding program can begin in earnest. Remember that the success of
any cannabis growing and breeding program hinges on the breeder maintaining accurate
records about parent plants and their descendants so that they can control
gene frequencies.
Let's say that you run a seed bank company called PALE GREEN LEAF ONLY
BUT EVERYTHING ELSE IS NOT UNIFORM LTD. The seeds that you create will
all breed pale green leaves and the customer will be happy. In reality,
customers want the exact same plant that won the cannabis cup last year
or at least something very close. So in reality, you will have to isolate
all the ^winning' traits before customers will be satisfied with what
they're buying.
The number of tests it takes to know any given genotype isn't certain.
You may have to use a wide selection of plants to achieve the goal, but
nevertheless it is still achievable. The next step in a breeding program
is to lock down other traits in that same population. Here is the hard
part.
When you are working on locking down a trait you must not eliminate other
desirable traits from the population. It is also possible to accidentally
lock down an unwanted trait or eliminate desired traits if you are not
careful. If this happens then you'll have to work harder to explore genotypes
through multiple cross tests and lock down the desired traits. Eventually,
through careful selection and record keeping you'll end up with a plant
that breeds true for all of the features that you want. In essence, you
will have your own genetic map of your cannabis plants.
Successful breeders don't try to map everything at once. Instead, they
concentrate on the main phenotypes that will make their plant unique and
of a high quality. Once they have locked down four or five traits they
can move on. True breeding strains are created slowly, in stages. Well
known true breeding strains like Skunk#l and Afghani#l took as long as
20 years to develop. If anyone states that they developed a true breeding
strain in one or two years you can be sure that the genetics they started
with were true breeding, homozygous, in the first place.
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 percent true breeding strain
for every single phenotype. Such a strain would be called a perfect IBL.
If you're able to lock down 90 percent 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 marijuana growing and 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 will certainly help to make the population more uniform for that trait.
Cannabis Cup
From the Cannabis Cup to marijuana hydro growing, you can find it here.
If you enjoyed these great marijuana facts, we have articles on growing cannabis (growing marijuana) facts and legalizing marijuana. Marijuana hydro growing at Marijuana Hydro.
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