Abstract:

Despite its importance as “poor man’s meat” in Uganda, there is no substantial
information on the amount of the common bean (Phaseolus vulgaris L.) diversity and its
dynamics in the farming communities. In addition to that, the introduction of improved
cultivars, urbanization, reduced farm-size as a result of population growth, and climate
change have forced farmers to make critical decisions that may have restructured the
diversity on-farm which may probably cause genetic erosion.
This study was conducted to investigate the amount of diversity of P. vulgaris and its
associated management in the selected rural and peri-urban communities of Mityana
district of central Uganda. The aim of the study was to determine the cultivar diversity of
P.vulgaris and the associated management practices while the specific objectives were to;
(i) determine the diversity P. vulgaris maintained by farmers, (ii) identify the
management practices and (iii) examine the seed system (seed provision, selection and
storage) of P. vulgaris in the communities. Data were purposefully collected from 120
households through household, surveys focus group discussions and direct field
observations. Diversity measures; cultivar richness and evenness as estimated by
Simpson’s index of diversity (1-D), farmers’ management practices and the seed system
mechanisms for both rural and peri-urban communities were obtained.
A total of 24 common bean cultivars were identified in the whole study area and an equal
cultivar richness of 21 cultivars was observed in both communities. Although both
communities had equal cultivar richness, the farmers in the peri-urban communities had a
significantly higher number of cultivars per household than their counterparts in rural
communities. Both communities had substantial cultivar evenness (0.81 and 0.82 in rural
and peri-urban, respectively) though some cultivars (e.g. Nambaale-omuwanvu,
Nambale-omumpi, Yellow and Kanyeebwa (A) were grown in relatively larger
proportions. Both communities had at least 30% of the total farms nurturing different sets
of cultivars. Using morphological evidence of taxonomy, farmers’ use of specific traits to
identify and manage cultivars highly coincided with the characters that grouped the
diversity in cluster analysis and principal component analysis. There were no variations
in the management practices employed by the rural and peri-urban farmers. Both seed
systems seemed stressed as most of the cultivars except Nambaale-omumpi, Nambaaleomuwanvu
and Yellow-omumpi, with in the communities had limited seed sources.
This study thus recommended that there is need to put in place incentive mechanisms that
can encourage a section of the farming community to continue conserving the diversity of
P.vulgaris on-farm to ensure its continued evolution and adaptation to changing biotic
and abiotic factors. Alternative strategies also need to be put in place and these include;
establishment of community gene banks to improve local seed systems, strengthening
participatory crop improvement that will add value to the least grown cultivars.