Genetic Patterns of Common-Bean Seed Acquisition and Early-stage Adoption among Farmer Groups in Western Uganda

Widespread adoption of new varieties can be valuable, especially in
developing countries, which tend to lack access to improved agricultural
production technologies. However, as farmers adopt new varieties, in
situ population structure and genetic diversity of their seed
holdings can change drastically. Consequences of adoption are still poorly
understood due to a lack of crop genetic diversity assessments and
detailed surveys of farmers’ seed management practices.  Common
bean (Phaseolus vulgaris) is an excellent model for these types of
studies, as it has a long history of cultivation among smallholder
farmers, exhibits eco-geographic patterns of diversity (e.g., Andean vs.
Mesoamerican gene-pools), and has been subjected to post-Columbian
dispersal and recent introduction of improved cultivars. The Hoima
district of western Uganda additionally provides an excellent social
setting for evaluating consequences of adoption because access to improved
varieties has varied across farmer groups in this production region. This
study establishes a baseline understanding of the common bean diversity
found among household producers in Uganda and compares the crop population
structure, diversity and consequences of adoption of household producers
with different adoption practices. Molecular diversity analysis, based on
4,955 single nucleotide polymorphism (SNP) markers, evaluated a total of
1,156 seed samples that included 196 household samples collected from
household producers in the Hoima district, nineteen breeder-selected
varieties used in participatory breeding activities that had taken place
prior to the study in the region, and a global bean germplasm collection.
Households that had participated in regional participatory breeding
efforts were more likely to adopt new varieties and, consequently,
diversify their seed stocks than those that had not participated. Of the
three farmer groups that participated in breeding efforts, households from
the farmer group with the longest history of bean production were more
likely to conserve “Seed Engufu”, a local “Calima”-type variety of the
Andean bean gene pool, and, at the same time, introduce rare Mesoamerican
gene pool varieties into household seed stocks.