Agriculture Reference
In-Depth Information
Genotype and phenotype
The genetic make-up of an individual is termed
its genotype. It relates to the sequence of DNA
nucleotides carried by the chromosomes. The
phenotype describes the physical appearance
of the organism and is the result of the com-
bined effect of the genes and the environment
in which the organism lives. It is difficult to
determine with any precision what are the
respective contributions of the genotype (G)
and the environment (E) from an examination
of the phenotype (P) of the individual. Where
qualitative traits are concerned, the contribu-
tion of the environment is negligible (P = G).
The quantitative characteristics resulting from
the interaction of a number of genes can be
influenced strongly by environmental factors
(P = G + E). The work of plant breeders con-
sists of the development of the genotype of a
cultivar.
2
The cultivation techniques used by
farmers will need to take into account environ-
mental factors (such as soil, fertilization, light,
etc.) on an ongoing basis in order to minimize
any divergence between the genetic potential
of the plant and the actual performance of the
cultivar under production (Fig. 4.2).
Fig. 4.2.
Plants of the same genotype
(Novosadska Konoplja) cultivated at a low sowing
density (left) and a high sowing density (right)
showing the importance of the environment on
plant architecture (phenotype).
Plant genetics and breeding
One of the most important practical applica-
tions of genetics is to be found in the selection
of plants and animals. Plant selectors use their
knowledge of plant genetics and apply this to
the development of cultivars in order to meet
the needs of farmers, as well as those of the
end user of the plant crop. Plant selection is
both an art and a science and involves the
development of plant genotypes. Humans
have, throughout modern history, at first
unconsciously and then consciously, domesti-
cated and then selected plants according to
their needs. Today, the hemp cultivars are
descendants of the hemp that was first culti-
vated by humans. Their ancient work was con-
ducted as an art, selecting plants empirically
with great success. With the discovery of
Mendelism, classical genetics was soon applied
in plant selection programmes. For the first
time, plant selection was conducted scientifi-
cally. Recently, molecular genetics has contrib-
uted to the development of plants using modern
biotechnological methods, such as genetic
engineering, to produce genetically modified
organisms (GMO) or transgenic plants.
Various aspects of industrial hemp breed-
ing are discussed by Hoffmann
et al
. (1970),
Berenji and Sikora (1996), Bócsa and Karus
(1998), Bócsa (1999), Finta-Korpel'ová and
Berenji (2007), etc.
Dempsey (1975) listed 18 institutes
involved in industrial hemp research in the
USSR (6), Eastern Europe (6), Western Europe
(4) and Asia (2).
Some of the frequently mentioned institu-
tions involved in industrial hemp breeding are:
•
Fleischmann Rudolf Research Institute of
the Károly Róbert College in Kompolt,
Hungary (formerly the 'Fleischmann
Rudolf' Agricultural Research Institute)
