6
1 Introduction
Species, varieties, cultivars:
A species is defined as a population in which a free gene flow and exchange
exists and the individuals of the population are able to produce descendant.
Species relevant for food and agriculture are conventionally divided into
cultivated varieties.
Modern varieties are - according to the seed certification and plant breeders'
rights - characterized by distinctness, uniformity and stability (upOV, 1992).
These varieties have been subject to breeding efforts and are protected in various
protection acts and registered under some seed trade acts. Registered varieties, for
which the protection period has expired and which may no longer be traded, are
listed in the country's seed office under the term old cultivars. Varieties grown
locally by farmers are landraces, which have been adapted to certain
environmental conditions and are not registered in official seed variety lists. They
are derived from various sources. In general, landraces contain high levels of
genetic diversity (e.g., Alika et aI., 1993, Ceccarelli et aI., 1992 ) and exceed the
modem varieties by numbers (Brush, 1991; Bolster, 1985t. Therefore, landraces
should be defined as populations and not as varieties. Consequently landraces are
the main focus of conservation efforts. Instead of landraces, developing countries -
for instance Ethiopia - prefer to call these populations "farmers' varieties",
crediting the breeding work done by farmers for centuries.
Plant breeders normally use advanced cultivars or breeders' lines as base for
further breeding activities or for creating a new variety. This material is derived
from elder varieties, old cultivars or landraces, and is improved by breeding
activities. The base material for a breeders' line may also be wild or weedy crop
relatives. These are distant relatives of crop species and coexist with the
agricultwal crops used and are often major weeds in the field of domesticated
crops. Wild or weedy crop relatives exist in or next to farmers' fields as well as in
the natural vegetation.
Accession:
An accession is the planting material of a variety stored in a conservation facility.
An accession represents the smallest storable unit of a cropvariety. By cereals, an
accession consists of approximately 500 to 1,000 seeds, which are dried and
usually conserved cold or frozen (Hammer, 1995).
6
There are communities in the Andes which grow 178 locally named potato varieties (Brush,
1991), or in the Peruvian Amazon 61 distinct cultivars of cassava are grown (Bolster, 1985).
1 Introduction
Species, varieties, cultivars:
A species is defined as a population in which a free gene flow and exchange
exists and the individuals of the population are able to produce descendant.
Species relevant for food and agriculture are conventionally divided into
cultivated varieties.
Modern varieties are - according to the seed certification and plant breeders'
rights - characterized by distinctness, uniformity and stability (upOV, 1992).
These varieties have been subject to breeding efforts and are protected in various
protection acts and registered under some seed trade acts. Registered varieties, for
which the protection period has expired and which may no longer be traded, are
listed in the country's seed office under the term old cultivars. Varieties grown
locally by farmers are landraces, which have been adapted to certain
environmental conditions and are not registered in official seed variety lists. They
are derived from various sources. In general, landraces contain high levels of
genetic diversity (e.g., Alika et aI., 1993, Ceccarelli et aI., 1992 ) and exceed the
modem varieties by numbers (Brush, 1991; Bolster, 1985t. Therefore, landraces
should be defined as populations and not as varieties. Consequently landraces are
the main focus of conservation efforts. Instead of landraces, developing countries -
for instance Ethiopia - prefer to call these populations "farmers' varieties",
crediting the breeding work done by farmers for centuries.
Plant breeders normally use advanced cultivars or breeders' lines as base for
further breeding activities or for creating a new variety. This material is derived
from elder varieties, old cultivars or landraces, and is improved by breeding
activities. The base material for a breeders' line may also be wild or weedy crop
relatives. These are distant relatives of crop species and coexist with the
agricultwal crops used and are often major weeds in the field of domesticated
crops. Wild or weedy crop relatives exist in or next to farmers' fields as well as in
the natural vegetation.
Accession:
An accession is the planting material of a variety stored in a conservation facility.
An accession represents the smallest storable unit of a cropvariety. By cereals, an
accession consists of approximately 500 to 1,000 seeds, which are dried and
usually conserved cold or frozen (Hammer, 1995).
6
There are communities in the Andes which grow 178 locally named potato varieties (Brush,
1991), or in the Peruvian Amazon 61 distinct cultivars of cassava are grown (Bolster, 1985).