Agriculture Reference
In-Depth Information
FIBRE QUALITY
.
The first selection studies modi-
fied the ratio of primary fibres to secondary
fibres successfully in favour of the latter. Despite
the fact that fineness, resistance to traction,
etc., are important aspects of fibre quality, it is
generally recognized that the cultivation and
fibre processing techniques have more poten-
tial for improving fibre quality than selection
alone (Müssig, 2003). This is an example of
the important role played by the environment,
compared to the genotypic potential, in the
phenotypic expression of fibre quality for com-
mercial hemp production.
of this cultivar contains high levels of the essen-
tial fatty acids, gammalinolenic acid (4.4%) and
stearidonic acid (1.7%), which are valuable as
nutraceuticals and dietary supplements
(Laakkonen and Callaway, 1998).
The Hungarian cultivar Fibrol has an
extractable seed oil content of over 35% (Bócsa
et al
., 2005). There are breeding attempts to
modify the fatty acid composition of hemp
seed oil (Finta-Korpel'ová, 2006).
Hemp cultivars
The majority of hemp cultivars are of open pol-
lination and are both monoecious and dioe-
cious, much as the hybridized cultivars based
on the principle of monosexuality. De Meijer
(1995, 1999) published an extensive study on
commercial industrial hemp cultivars, including
French, Hungarian, Polish, Romanian,
Ukrainian, Russian, Italian, Serbian, German
and Far Eastern cultivars, as well as drug
strains.
All new cultivars must be
unique
(clearly
distinct from all existing cultivars),
homoge-
nous
and
stable
in their essential characteris-
these requirements are met. A compulsory
prerequisite for all new cultivars is that they
demonstrate improved performance relative to
existing varieties for the traits of interest. In
order to recognize the agronomic value of a
new cultivar, its traits, and therefore its genet-
ics, must be preserved post-selection (Fig. 4.7).
With hemp, the operation to preserve these
traits during the selection process requires as
much effort as the operation devoted to the
creation of a new product. The most com-
monly employed method for preserving the
genetic identity of a cultivar is mass selection.
CANNABINOIDS
.
Respecting the increasingly
rigorous requirements imposed by legisla-
tion (Berenji, 1998), low tetrahydrocannabi-
nol (THC; < 0.2%) and even THC-free hemp
cultivars were bred primarily by Ukrainian
and French hemp breeders (Beherec, 2000).
Illegal, predominantly amateur plant breed-
ers produced marijuana hemp with very high
THC levels. There is an increasing demand
for adjusting the cannabinoid content
and composition, ranging from predomi-
nation to complete elimination of certain
cannabinoids from the plant, which is
especially important in the case of pharma-
ceutical hemp (Berenji and Sabo, 1998).
Pharmaceutical hemp cultivars have been
bred in the Netherlands by HortaPharm BV
and licensed to GW Pharmaceuticals Ltd for
commercial production.
HEMP FOR OIL PRODUCTION
.
An increase in the
yield of oil is of great importance for oil hemp
as it must compete with other plants capable
of delivering far more oil. It has been observed
that 70-90% more oil is produced from mono-
ecious hemp than from dioecious varieties.
The use of intravarietal selection for an
increase in seed yield, including an increase
in oil content, was begun in 1997 by Bócsa
et al
. (1999).
The Finnish cultivar Finola, originally
known as FIN-314, is cultivated specifically for
seed production and oil extraction. In its natu-
ral environment in Finland, the oil content of
this short, early maturing, frost-resistant culti-
var is 35% (Callaway, 2002). According to
Scheifele (2000), the cold-pressing extractable
oil content of this cultivar is 27%. The seed oil
Production of certified seed stock
The commercial seed industry consists of all
the people, businesses, seed companies and
commercial enterprises involved in the produc-
tion and commercialization of certified seed for
farmers. During the production of seeds, the
identity and purity of cultivars are evaluated in
the field. The male/female ratio is monitored
closely, as is the THC concentration, aspects
that are uniquely characteristic of the hemp
