Breeding

BobNarley · 05-31-2008, 10:20 AM

Breeding
Humans have been breeding marijuana informally for
thousands of years. The first farmers chose seeds from the best

plants. Over many generations the plant was differentiated into
varieties which had different uses and thrived under various en-
vironmental conditions.
Scientific breeding did not begin until Gregor Mendel's ex-
periments on inherited characteristics were discovered. Mendel
crossed peas with differing characteristics and found that the off-
spring plants inherited traits from their parents in a logical, predic-
table, statistical way.
Today we know that each cell contains a set of chemical
blueprints regarding every aspect of its existence. These chemical
codes are called chromosomes and they consist of long double
strands of sugar which have ""bases" consisting of one of four
amino acids. Sets of three of these amino acid bases form genes
which are ""read" by structures in the cell and direct it in its life pro-
cesses.
Chromosomes are found in pairs in most cells. Half of each
pair of chromosomes is contributed by the male through pollen and
half by the female. Marijuana has 10 pairs or 20 chromosomes.
Each chromosome's genes are lined up in a specific order. The
other member of the pair has a corresponding gene in the same
location. Sometimes, a single gene is responsible for a
characteristic. In other cases, several genes are responsible, often in
a complex series of reactions.
There has been very little formal genetic work on marijuana.
Almost all of the research is the result of observation by cultivators.
However, the cell and its chromosomes are easily observed using a
high-powered microscope. Even an inexpensive instrument allows
one to see the chromosomes during mitosis (cell division). The
chromosomes line up in pairs and then reproduce themselves as the
cell splits into two. When reproductive cells are produced, the pairs
of chromosomes split and only one chromosome of each pair goes
into each reproductive cell. (Photographs can be taken with the aid
of a 35 mm SLR camera and an inexpensive adapter tube.)
About 2% of the time, the genes ""jump" from one member of
the pair of chromosomes to the other. This is a significant fact in
breeding because it gives individual chromosomes a means of
changing information regarding the characteristics for which they
are coded.
Breeding would be a relatively simple task if only one trait or
characteristic were involved. However there are many factors to
consider when choosing plants for breeding. These include: poten-
cy, taste, aroma, color, maturation time, yield, height, branching
habits, adaption to low-light conditions, resistance to pests or
diseases, leaf drop at maturity, and sterility.
When a plant ""breeds true" it means that most of the cor-
responding genes on each of the pairs of chromosomes of the 10
pairs have the same information. However, plants of different
varieties which are crossed are hybrids, and many of the correspon-
ding genes on the two sets of chromosomes have information which
is in conflict. For instance, the first generation cross (an F1 hybrid)
may contain genes from one parent programmed for tall plants and

genes from the other parent programmed for short stature. In this
case the plants all have approximately the same height, intermediate
between the two parents. When two F1 hybrids are crossed,
however, the plants are either tall, intermediate or short. The
reason is that some of the plants have genes for tallness, some for
shortness and others for both.
Many of the important characteristics of marijuana seem to be
coded for ""partial dominance" as was just described. Aroma,
taste, and potency seem to fall into this category. When more than
one gene is involved, there can be enormous numbers of possible
combinations.
Some characteristics are coded on genes which are either domi-
nant or recessive. According to Robert Connell Clarke, author of
Manjuana Botany, tall height, unwebbed leaves, green rather than
purple coloring on calyxes (seed bracts), and large-size seeds are all
dominant genes. A cross between two plants with conflicting genes
would result in the F1 generation all showing the dominant trait. A
cross between two F1 plants results in a majority of the plants in-
dicating the dominant trait and only a few, those without the domi-
nant gene on either chromosome, indicating the information found
on the recessive gene.
It is difficult for the hobbyist or grower to institute a scientific
breeding program because thousands of plants must be grown to
find one specimen which meets ideal breeding requirements.
Growers have a limited amount of space to devote to the plants and
thus have trouble sorting out the crosses. Cultivators can select the
best plants in the garden for breeding. Sometimes a plant has one
outstanding characteristic but is unexceptional in other respects.
This characteristic can be introduced into the breeding pool and
then the undesirable traits can be ""sorted out".
Marijuana is especially difficult to breed scientifically because
half the plants, those bearing pollen, carry genetic information for
hidden factors. An observer has few means of judging the genetic
potential of male plants regarding yield, bud structure, and even
potency. There is some correlation between the male's potency and
that of its daughters. One way to solve this problem is to induce
male flowers on female plants. Then the characteristics of both
parents are known and all the resulting plants have only female
chromosomes.
As in humans, gender in cannabis is determined by the ""X"
and ""Y" chromosomes. The female has two X chromosomes and
the male has one X and one Y. When the male plant produces
pollen, half of the reproductive cells receive X and half Y.
However, when male flowers are artificially induced in female
plants, the pollen contains only X chromosomes, the only sex
chromosomes the female plant has. All the resulting seeds contain
two X chromosomes, one from each parent.
To induce male flowers in female plants, the plants are sprayed
with gibberellic acid or watered with an aspirin/water solution.
Gibberellic acid is a plant hormone originally isolated from
mold-infested rice. Symptoms of the infection include extraor-

dinary vertical growth. Gibberellic acid affects plants in a variety of
ways. In marijuana, it causes extension of all stems on which it is
sprayed, and if used before flowers develop, it occasionally induces
""sex reversal" in females: male flowers develop on sprayed areas.
The plant's genetic structure remains the same; however, the sex
characteristics are altered. In a general way this is similar to a sex
change operation; the genetic information contains information for
one sex, but the hormones which are introduced by pill or injection
artificially induce physiological changes in the body, including
development of the other sex's sexual characteristics.
Several correspondents have described the results of adding
aspirin to their water. One grower used two aspirin in a gallon of
water when the plants were in their third week of flowering. He said
that the plants grew thousands of pollen sacs which contained fer-
tile pollen.
The most methodical way to breed marijuana using these
substances is to allow the plants to flower after taking several clones
from each plant. Once the plants are harvested, cured and tested,
the cuttings of all except those plants selected as the best for
breeding are eliminated. When the plants are large enough to pro-
duce adequate amounts of seed for the breeder's purpose, some of
the plants are kept as females, and male flowers are induced in
others. Then the plants are bred.
The first step involves gathering the pollen. Since cannabis is
usually wind-pollinated, it produces an abundance of pollen which
floats easily in the air. The male plants are placed in a separate
draft-free location and the pollen drops onto unprinted paper
placed underneath the plant. However, if there are several plants in
the same room, the different plants' pollen may become con-
taminated with each other. If the plants are bent or turned on their
sides so that the pollen has to drop through less air, more pollen
collects. Plants placed in a cardboard box are even less susceptible
to draft.
Some growers collect pollen by cutting the flower spikes off the
plants just as the flowers are to open. These spikes are placed in a
paper bag so no pollen is lost. Pollen can also be collected by plac-
ing a white paper bag around flower spikes. White paper is used so
that light rays are reflected rather than absorbed by the bag and
turned into heat, which may damage the plant. Non-coated parch-
ment paper breathes and eliminates humidity problems.
Once the pollen is collected, the female flowers are fertilized.
(If pollen is scarce, it is diluted 10-100 parts by weight with flour).
Pollination can be accomplished simply by placing a bag filled with
pollen around a bud and then shaking it. The pollen settles for a
day or two and then is removed. Another method is to ""paint" the
pollen onto the female flowers using a small watercolor brush. One
grower insists that it is easiest to pollinate using your fingers.
The best time to pollinate marijuana is when the flowers are
well developed but still fresh, and have gone through several stages
of growth and filling out.
Breeding is a very detailed subject and this is just a cursory

discussion of it. For more information, I recommend the book,
Marijuana Botany by R.C. Clarke.

05-31-2008, 10:20 AM	#1 (permalink)
BobNarley My Mood: Join Date: May 2007 Location: Mojove Desert-Southern California Posts: 530 gRamz: 13,472 Danks: 26 Danked 17 Times in 14 Posts	Breeding Breeding Humans have been breeding marijuana informally for thousands of years. The first farmers chose seeds from the best plants. Over many generations the plant was differentiated into varieties which had different uses and thrived under various en- vironmental conditions. Scientific breeding did not begin until Gregor Mendel's ex- periments on inherited characteristics were discovered. Mendel crossed peas with differing characteristics and found that the off- spring plants inherited traits from their parents in a logical, predic- table, statistical way. Today we know that each cell contains a set of chemical blueprints regarding every aspect of its existence. These chemical codes are called chromosomes and they consist of long double strands of sugar which have ""bases" consisting of one of four amino acids. Sets of three of these amino acid bases form genes which are ""read" by structures in the cell and direct it in its life pro- cesses. Chromosomes are found in pairs in most cells. Half of each pair of chromosomes is contributed by the male through pollen and half by the female. Marijuana has 10 pairs or 20 chromosomes. Each chromosome's genes are lined up in a specific order. The other member of the pair has a corresponding gene in the same location. Sometimes, a single gene is responsible for a characteristic. In other cases, several genes are responsible, often in a complex series of reactions. There has been very little formal genetic work on marijuana. Almost all of the research is the result of observation by cultivators. However, the cell and its chromosomes are easily observed using a high-powered microscope. Even an inexpensive instrument allows one to see the chromosomes during mitosis (cell division). The chromosomes line up in pairs and then reproduce themselves as the cell splits into two. When reproductive cells are produced, the pairs of chromosomes split and only one chromosome of each pair goes into each reproductive cell. (Photographs can be taken with the aid of a 35 mm SLR camera and an inexpensive adapter tube.) About 2% of the time, the genes ""jump" from one member of the pair of chromosomes to the other. This is a significant fact in breeding because it gives individual chromosomes a means of changing information regarding the characteristics for which they are coded. Breeding would be a relatively simple task if only one trait or characteristic were involved. However there are many factors to consider when choosing plants for breeding. These include: poten- cy, taste, aroma, color, maturation time, yield, height, branching habits, adaption to low-light conditions, resistance to pests or diseases, leaf drop at maturity, and sterility. When a plant ""breeds true" it means that most of the cor- responding genes on each of the pairs of chromosomes of the 10 pairs have the same information. However, plants of different varieties which are crossed are hybrids, and many of the correspon- ding genes on the two sets of chromosomes have information which is in conflict. For instance, the first generation cross (an F1 hybrid) may contain genes from one parent programmed for tall plants and genes from the other parent programmed for short stature. In this case the plants all have approximately the same height, intermediate between the two parents. When two F1 hybrids are crossed, however, the plants are either tall, intermediate or short. The reason is that some of the plants have genes for tallness, some for shortness and others for both. Many of the important characteristics of marijuana seem to be coded for ""partial dominance" as was just described. Aroma, taste, and potency seem to fall into this category. When more than one gene is involved, there can be enormous numbers of possible combinations. Some characteristics are coded on genes which are either domi- nant or recessive. According to Robert Connell Clarke, author of Manjuana Botany, tall height, unwebbed leaves, green rather than purple coloring on calyxes (seed bracts), and large-size seeds are all dominant genes. A cross between two plants with conflicting genes would result in the F1 generation all showing the dominant trait. A cross between two F1 plants results in a majority of the plants in- dicating the dominant trait and only a few, those without the domi- nant gene on either chromosome, indicating the information found on the recessive gene. It is difficult for the hobbyist or grower to institute a scientific breeding program because thousands of plants must be grown to find one specimen which meets ideal breeding requirements. Growers have a limited amount of space to devote to the plants and thus have trouble sorting out the crosses. Cultivators can select the best plants in the garden for breeding. Sometimes a plant has one outstanding characteristic but is unexceptional in other respects. This characteristic can be introduced into the breeding pool and then the undesirable traits can be ""sorted out". Marijuana is especially difficult to breed scientifically because half the plants, those bearing pollen, carry genetic information for hidden factors. An observer has few means of judging the genetic potential of male plants regarding yield, bud structure, and even potency. There is some correlation between the male's potency and that of its daughters. One way to solve this problem is to induce male flowers on female plants. Then the characteristics of both parents are known and all the resulting plants have only female chromosomes. As in humans, gender in cannabis is determined by the ""X" and ""Y" chromosomes. The female has two X chromosomes and the male has one X and one Y. When the male plant produces pollen, half of the reproductive cells receive X and half Y. However, when male flowers are artificially induced in female plants, the pollen contains only X chromosomes, the only sex chromosomes the female plant has. All the resulting seeds contain two X chromosomes, one from each parent. To induce male flowers in female plants, the plants are sprayed with gibberellic acid or watered with an aspirin/water solution. Gibberellic acid is a plant hormone originally isolated from mold-infested rice. Symptoms of the infection include extraor- dinary vertical growth. Gibberellic acid affects plants in a variety of ways. In marijuana, it causes extension of all stems on which it is sprayed, and if used before flowers develop, it occasionally induces ""sex reversal" in females: male flowers develop on sprayed areas. The plant's genetic structure remains the same; however, the sex characteristics are altered. In a general way this is similar to a sex change operation; the genetic information contains information for one sex, but the hormones which are introduced by pill or injection artificially induce physiological changes in the body, including development of the other sex's sexual characteristics. Several correspondents have described the results of adding aspirin to their water. One grower used two aspirin in a gallon of water when the plants were in their third week of flowering. He said that the plants grew thousands of pollen sacs which contained fer- tile pollen. The most methodical way to breed marijuana using these substances is to allow the plants to flower after taking several clones from each plant. Once the plants are harvested, cured and tested, the cuttings of all except those plants selected as the best for breeding are eliminated. When the plants are large enough to pro- duce adequate amounts of seed for the breeder's purpose, some of the plants are kept as females, and male flowers are induced in others. Then the plants are bred. The first step involves gathering the pollen. Since cannabis is usually wind-pollinated, it produces an abundance of pollen which floats easily in the air. The male plants are placed in a separate draft-free location and the pollen drops onto unprinted paper placed underneath the plant. However, if there are several plants in the same room, the different plants' pollen may become con- taminated with each other. If the plants are bent or turned on their sides so that the pollen has to drop through less air, more pollen collects. Plants placed in a cardboard box are even less susceptible to draft. Some growers collect pollen by cutting the flower spikes off the plants just as the flowers are to open. These spikes are placed in a paper bag so no pollen is lost. Pollen can also be collected by plac- ing a white paper bag around flower spikes. White paper is used so that light rays are reflected rather than absorbed by the bag and turned into heat, which may damage the plant. Non-coated parch- ment paper breathes and eliminates humidity problems. Once the pollen is collected, the female flowers are fertilized. (If pollen is scarce, it is diluted 10-100 parts by weight with flour). Pollination can be accomplished simply by placing a bag filled with pollen around a bud and then shaking it. The pollen settles for a day or two and then is removed. Another method is to ""paint" the pollen onto the female flowers using a small watercolor brush. One grower insists that it is easiest to pollinate using your fingers. The best time to pollinate marijuana is when the flowers are well developed but still fresh, and have gone through several stages of growth and filling out. Breeding is a very detailed subject and this is just a cursory discussion of it. For more information, I recommend the book, Marijuana Botany by R.C. Clarke.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode