Hydrolife Magazine October/November 2016 (USA Edition)

grow
Cannabis normally requires long
dark periods to trigger flowering,
but there are varieties that will flower
regardless of the lighting conditions.
These are known as autoflowering
varieties. Not all cannabis traits are
as simple to explain, which is part of
what makes autoflowering a good example
for beginning breeders to start
with. For the purposes of this article, a
few exceptions and special cases have
been omitted for clarity, since even
at the most basic level, it is a complicated
enough topic that to some may
seem confusing at first.
Gregor Mendel, a friar who conducted
experiments with pea plants in the mid-
1800s, tracked traits such as seed shape
and flower color, and developed basic
rules for understanding genetic inheritance
such as the concept of dominant
and recessive traits. Although some
traits are complicated and require more
than one gene to express, autoflowering
is one of the most basic types of genetic
traits and follows the laws of simple
recessiveness and dominance. Specifically,
it is a recessive trait.
Of importance to breeders, both experienced
and aspiring, autoflowering is
an easily observable simple Mendelian
recessive trait. It is generally quick and
easy to determine if a given adolescent
plant is autoflowering or standard just
by keeping it in short (or non-existent)
dark periods for a few weeks. If the
plant stays in growth, it is standard, if it
flowers it is autoflowering.
Cannabis is a diploid, in other words,
it gets one chromosome from the pollen
of the father, and one from the ovum
of the mother. This means it will have
two genes (one from each chromosome
strand), each of which can be one of two
alleles, either autoflowering or not.
If we refer to the photodependant
(standard) allele as P (upper case P),
and the non-photodependant allele
as p (lower case p), then the child
plant will receive two—one from each
parent. If the father is true breeding
(homozygous) for photodependancy, it
will have the allele P on both genes—
the same is true for the mother. Seeds
made from such pairings will result
in offspring that is also true breeding
for photodependancy. The father will
contribute either a P or a P (because he
has two big Ps, and will pass on one or
the other). The mother will contribute
either a P or a P (because she has two,
and will pass on one or the other).
While technically there are four
combinations possible, effectively it
doesn’t make much difference because
all of the combinations result in PP
(true breeding for photodependancy).
This is why breeding a standard
cannabis plant with another standard
cannabis plant will result in standard
cannabis offspring. The same is true
of autoflowering. If both parents are
true breeding for autoflowering, they
will each have pp, and their offspring
will autoflower (since they will receive
a p from each parent). However, if one
parent is PP (standard) and the other is
autoflowering (pp), then all of the seeds
will be Pp, since they will get one of
the two P from the first parent, and one
of the two p from the second parent.
Having both the allele P and the allele
p (heterogeneous for autoflowering)
makes them a hybrid.
“Cannabis
is a diploid, in other words, it gets one
chromosome from the pollen of the father,
and one from the ovum of the mother.”
28 grow. heal. live. enjoy.
myhydrolife.com