2.4 Methods for Conservation of PGRFA
43
The limitations of ex situ conservation can be summarized as follows:
l. Because of the current state of technology, many important species cannot be
stored in seed genebanks, because they do not have orthodox seeds.
Consequently, these species are underrepresented in germplasm collections.
2. The ex situ storage methods do not guarantee a long-term conservation without
any negative impacts on the diversity of the plant genetic resources. Genetic
shift due to insufficient and inappropriate regeneration, storage, health care,
and existing capacities, are decreasing the genetic variation, which existed in
the original collection sample.
3. Because of the conservation method, ex situ conserved genetic resources are
not exposed to natural and artificial pressure, and can therefore not be expected
to evolve and adapt to environmental changes.
Although there are not very many studies yet concerning the potential of on-farm
management, the limitations known are:
l. If on-farm management is conceptualized by minimizing the area for each
variety to be conserved, there is a risk that some allelic diversity will be lost in
a limited population.
2. The cultural and socio-economic factors are important for the development of
diversity on the local level, but they are related to ecological, social and
technological development. Therefore, the future interest of local communities
and individuals in conservation activities cannot be taken as granted.
3. The promotion of on-farm management would be pointless without an very
long time horizon of at least 50 to 100 years, which increases the risk of every
management concept.
In addition to these limitations, the main advantages of on-farm conservation can
be described as follows:
1. On-farm management, as a dynamic form of plant genetic resources
management, enables the processes of natural and artificial selection to
continue. Consequently, despite the loss of some allelic diversity, on-farm
management promotes the development of diversity (seen in a perspective of
approximately 100 years).
2. It allows the possibility of conserving a large range of potentially interesting
alleles.
3. It facilitates research on species in their natural habitats.
4. It assures protection of associated species, which - in spite of no economic
value - may contribute to the functioning and long-term productivity of
ecosystems.
5. On-farm conservation is especially desirable for crops which do not receive
sufficient attention by the formal sector.
6. On-farm management may contribute to an agricultural development while
conserving diversity. Linking the management of PGRF A to the improvement
of landraces through breeding may be an appropriate strategy for improving
farmers' livelihoods in marginal areas as long as there are no economic
alternatives.
43
The limitations of ex situ conservation can be summarized as follows:
l. Because of the current state of technology, many important species cannot be
stored in seed genebanks, because they do not have orthodox seeds.
Consequently, these species are underrepresented in germplasm collections.
2. The ex situ storage methods do not guarantee a long-term conservation without
any negative impacts on the diversity of the plant genetic resources. Genetic
shift due to insufficient and inappropriate regeneration, storage, health care,
and existing capacities, are decreasing the genetic variation, which existed in
the original collection sample.
3. Because of the conservation method, ex situ conserved genetic resources are
not exposed to natural and artificial pressure, and can therefore not be expected
to evolve and adapt to environmental changes.
Although there are not very many studies yet concerning the potential of on-farm
management, the limitations known are:
l. If on-farm management is conceptualized by minimizing the area for each
variety to be conserved, there is a risk that some allelic diversity will be lost in
a limited population.
2. The cultural and socio-economic factors are important for the development of
diversity on the local level, but they are related to ecological, social and
technological development. Therefore, the future interest of local communities
and individuals in conservation activities cannot be taken as granted.
3. The promotion of on-farm management would be pointless without an very
long time horizon of at least 50 to 100 years, which increases the risk of every
management concept.
In addition to these limitations, the main advantages of on-farm conservation can
be described as follows:
1. On-farm management, as a dynamic form of plant genetic resources
management, enables the processes of natural and artificial selection to
continue. Consequently, despite the loss of some allelic diversity, on-farm
management promotes the development of diversity (seen in a perspective of
approximately 100 years).
2. It allows the possibility of conserving a large range of potentially interesting
alleles.
3. It facilitates research on species in their natural habitats.
4. It assures protection of associated species, which - in spite of no economic
value - may contribute to the functioning and long-term productivity of
ecosystems.
5. On-farm conservation is especially desirable for crops which do not receive
sufficient attention by the formal sector.
6. On-farm management may contribute to an agricultural development while
conserving diversity. Linking the management of PGRF A to the improvement
of landraces through breeding may be an appropriate strategy for improving
farmers' livelihoods in marginal areas as long as there are no economic
alternatives.