[cannebosanac]

poglavlje 2 nastavak

Modern fiber or hemp farmers use commercially pro-
duced high fiber content strains of even maturation. Mono-
ecious strains are often used because they mature more
evenly than dioecious strains. The hemp breeder sets up
test plots where phenotypes can be recorded and controlled
crosses can be made. A farmer may leave a portion of his
crop to develop mature seeds which he collects for the fol-
lowing year. If a hybrid variety is grown, the offspring will
not ail resemble the parent crop and desirable character-
istics may be lost.
Growers of seeded marijuana for smoking or hashish
production collect vast quantities of seeds that fall from
the flowers during harvesting, drying, and processing. A
mature pistillate plant can produce tens of thousands of
seeds if freely pollinated. Sinsemilla marijuana is grown by
removing all the staminate plants from a patch, eliminating
every pollen source, and allowing the pistillate plants to
produce massive clusters of unfertilized flowers.
Various theories have arisen to explain the unusually
potent psychoactive properties of unfertilized Cannabis.
In general these theories have as their central theme the
extraordinarily long, frustrated struggle of the pistillate
plant to reproduce, and many theories are both twisted and
romantic. What actually happens when a pistillate plant
remains unfertilized for its entire life and how this ulti-
mately affects the cannabinoid (class of molecules found
only in Cannabis) and terpene (a class of aromatic organic
compounds) levels remains a mystery. It is assumed, how-
ever, that seeding cuts the life of the plant short and THC
(tetrahydrocannabinol the major psychoactive compound
in Cannabis) does not have enough time to accumulate.
Hormonal changes associated with seeding definitely affect
all metabolic processes within the plant including canna-
binoid biosynthesis. The exact nature of these changes is
unknown but probably involves imbalance in the enzymatic
systems controlling cannabinoid production. Upon fertili-
zation the plant's energies are channeled into seed produc-
tion instead of increased resin production. Sinsemilla plants
continue to produce new floral clusters until late fail, while
seeded plants cease floral production. It is also suspected
that capitate-stalked trichome production might cease
when the calyx is fertilized. If this is the case, then sinse-
milla may be higher in THC because of uninterrupted floral
growth, trichome formation and cannabinoid production.
What is important with respect to propagation is that once
again the farmer has interfered with the life cycle and no
naturally fertilized seeds have been produced.
The careful propagator, however, can produce as
many seeds of pure types as needed for future research
without risk of pollinating the precious crop. Staminate
parents exhibiting favorable characteristics are reproduc-
tively isolated while pollen is carefully collected and
applied to only selected flowers of the pistillate parents.
Many cultivators overlook the staminate plant, con-
sidering it useless if not detrimental. But the staminate
plant contributes half of the genotype expressed in the
offspring. Not only are staminate plants preserved for
breeding, but they must be allowed to mature, uninhibited,
until their phenotypes can be determined and the most
favorable individuals selected. Pollen may also be stored
for short periods of time for later breeding. Biology of Pollination
Pollination is the event of pollen landing on a stig-
matic surface such as the pistil, and fertilization is the
union of the staminate chromosomes from the pollen with
the pistillate chromosomes from the ovule.
Pollination begins with dehiscence (release of pollen)
from staminate flowers. Millions of pollen grains float
through the air on light breezes, and many land on the
stigmatic surfaces of nearby pistillate plants. If the pistil is
ripe, the pollen grain will germinate and send out a long
pollen tube much as a seed pushes out a root. The tube
contains a haploid (in) generative nucleus and grows
downward toward the ovule at the base of the pistils.
When the pollen tube reaches the ovule, the staminate
haploid nucleus fuses with the pistillate haploid nucleus
and the diploid condition is restored. Germination of the
pollen grain occurs 15 to 20 minutes after contact with
the stigmatic surface (pistil); fertilization may take up to
two days in cooler temperatures. Soon after fertilization,
the pistils wither away as the ovule and surrounding calyx
begin to swell. If the plant is properly watered, seed will
form and sexual reproduction is complete. It is crucial that
no part of the cycle be interrupted or viable seed will not
form. If the pollen is subjected to extremes of tempera-
ture, humidity, or moisture, it will fail to germinate, the
pollen tube will die prior to fertilization, or the embryo
will be unable to develop into a mature seed. Techniques
for successful pollination have been designed with all these
criteria in mind.
Controlled versus Random Pollinations
The seeds with which most cultivators begin represent
varied genotypes even when they originate from the same
floral cluster of marijuana, and not all of these genotypes
will prove favorable. Seeds collected from imported ship-
ments are the result of totally random pollinations among
many genotypes. If elimination of pollination was at-
tempted and only a few seeds appear, the likelihood is very
high that these pollinations were caused by a late flowering
staminate plant or a hermaphrodite, adversely affecting the
genotype of the offspring. Once the offspring of imported
strains are in the hands of a competent breeder, selection
and replication of favorable phenotypes by controlled
breeding may begin. Only one or two individuals out of
many may prove acceptable as parents. If the cultivator
allows random pollination to occur again, the population
not only fails to improve, it may even degenerate through
natural and accidental selection of unfavorable traits. We
must therefore turn to techniques of controlled pollination
by which the breeder attempts to take control and deter-
mine the genotype of future offspring.
Data Collection
Keeping accurate notes and records is a key to suc-
cessful plant-breeding. Crosses among ten pure strains (ten
staminate and ten pistillate parents) result in ten pure and
ninety hybrid crosses. It is an endless and inefficient task
to attempt to remember the significance of each little num-
ber and colored tag associated with each cross. The well-
organized breeder will free himself from this mental burden
and possible confusion by entering vital data about crosses,
phenotypes, and growth conditions in a system with one
number corresponding to each member of the population.
The single most important task in the proper collec-
tion of data is to establish undeniable credibility. Memory
fails, and remembering the steps that might possibly have
led to the production of a favorable strain does not con-
stitute the data needed to reproduce that strain. Data is
always written down; memory is not a reliable record. A
record book contains a numbered page for each plant, and
each separate cross is tagged on the pistillate parent and
recorded as follows: "seed of pistillate parent X pollen or
staminate parent." Also the date of pollination is included
and room is left for the date of seed harvest. Samples of
the parental plants are saved as voucher specimens for later
characterization and analysis.
Pollination Techniques
Controlled hand pollination consists of two basic
steps: collecting pollen from the anthers of the staminate
parent and applying pollen to the receptive stigmatic sur-
faces of the pistillate parent. Both steps are carefully con-
trolled so that no pollen escapes to cause random pollina-
tions. Since Cannabis is a wind-pollinated species, enclo-
sures are employed which isolate the ripe flowers from
wind, eliminating pollination, yet allowing enough light
penetration and air circulation for the pollen and seeds to
develop without suffocating. Paper and very tightly woven
cloth seem to be the most suitable materials.