Agriculture Reference
In-Depth Information
of G E to develop locally-adapted varieties through decentralized selec-
tion and participatory breeding has been proposed as a solution to breed-
ing for organic and low-input systems. The basis for many participatory
plant breeding projects lies in the use of the genetic diversity present in
farmer varieties and in farmers' specifi c knowledge and evaluation of va-
rietal traits of importance in their agricultural environment. The need for
specifi c traits (both agronomic and quality) for different environments and
management practices is currently not considered in the offi cial varietal
registration process. In developed countries, interest in on-farm breeding
and conservation has been primarily from organic and low-input farmers
because they face many challenges not present in conventional systems,
including more heterogeneous environmental conditions, the absence of
adapted varieties, and a lack of interest by the commercial seed sector in
producing varieties for these systems [15,18].
Farmers interested in on-farm breeding often look for more diverse
varieties because they want these varieties to be able to evolve specifi c ad-
aptation to their conditions, and because genetic heterogeneity may buffer
crop responses to unpredictable environmental conditions. The agronomic
benefi ts of diversity include improved durability of disease resistance and
reduction of disease severity [16,21] and greater buffering capacity of
heterogeneous populations [22,23]. In heterogeneous populations, pheno-
typic stability may arise from genetic diversity that allows the fl exible ex-
pression of component traits that lead to higher stability for complex traits
such as yield and quality. In addition to contributing to the development
of well-adapted varieties, the conservation of genetic diversity within va-
rieties is also important to maintain the adaptive potential of these variet-
ies. Contrasted selection pressures over multiple farms will preserve the
greatest level of diversity at the meta-population level (i.e., considering
all the farms together), even if each population loses a portion of its initial
diversity in the process of selection for local adaptation [24-28]. Selection
and conservation objectives benefi t from the ability to evaluate and use the
widest range of genetic diversity available.
Because of the benefi ts drawn from diversity under organic conditions,
organic farmers in developed countries have been key in the development
of seed exchange and seed saving organizations [29]. The work presented
in this paper was possible because of the engagement and activities of
