Insights From Farmer-Engaged Research in Climbing Bean Genotype by Cropping System Interactions in Northern Rwanda.

Common bean (Phaseolus vulgaris) is an important staple crop in Rwanda. Smallholder farmers frequently grow climbing beans in polycultures and often as an intercrop with maize, yet the majority of plant breeding programs develop and select bean cultivars under monoculture conditions. Previous research shows mixed evidence of bean genotype by cropping system interactions. Participatory variety selection (PVS) programs incorporate to varying degrees farmers’ knowledge and experimentation in the development of new cultivars, although they less commonly address genotype by cropping system interactions. This research combines agronomic assessment of bean genotype by cropping system interactions with farmer PVS to understand Rwandan farmer knowledge about these interactions. In a mother-baby trial design, 5 bean genotypes and 1 farmer mixture were each planted in a monocrop and an intercrop with 1 maize genotype. These randomized complete block experiments were replicated 4 times on 2 research stations and in 8 farmers’ field over 2 seasons in 2011. Farmers managed the plots and researchers visited regularly to monitor and collect data on plant morphology and yield. At the end of each season farmers anonymously evaluated the cropping system, the bean genotypes in the monocrop, and then in the intercrop. Following the evaluation farmers discussed the reasons they chose each genotype in the respective system. Preferences for a certain bean genotype in a selected system varied across locations but frequently matched yield data. In some sites, farmers selected the same genotype for both a monoculture and an interculture, while in other sites farmers preferred different varieties for each system. Overall farmers identified specific traits associated with adaptability in an intercrop and there is evidence Rwandan farmers have developed their own techniques for testing genotypes in different systems.