Tropentag, September 16 - 18, 2026, Göttingen "Towards multi-functional agro-ecosystems promoting climate-resilient futures"

Extension-led early-generation testing for faster, demand-driven bean breeding in East Africa

¹The Alliance of Bioversity International & CIAT, Kenya
²Pan-Africa Bean Research Alliance, Crops for Nutrition and Health, Kenya
³Tanzania Agricultural Research Institute, Tanzania
⁴Kenya Agricultural and Livestock Research Organization (KALRO), Kenya

Abstract

Common bean improvement in East Africa is constrained by a mismatch between the environments in which breeding decisions are made and those in which smallholder farmers grow the crop. On-station trials remain essential, but they cannot fully capture variation in soils, climate, farmer management and market demand. We argue that testing early-generation genotypes under on-farm conditions can strengthen selection before candidate varieties approach release. We implemented an extension-led platform linking breeders, agronomists, research institutions, extension officers, farmers and market actors. Unlike conventional participatory variety selection, which commonly engages farmers when candidate varieties are close to release, the platform incorporates farmer preference, agronomic performance and market requirements while breeding decisions can still be changed. Following the tricot approach, each farmer grows and compares three randomly assigned Stage 1 genotypes in their own field. Breeders provide seed, protocols, digital tools and oversight, while extension officers facilitate trial establishment, periodic assessment and farmer evaluation. Farmers manage and monitor the trials under local conditions, using the same practices applied to their own bean crops. During extension visits, farmers and extension officers collect data together, and farmers share accumulated observations, indicating which genotypes they prefer and why. Open Data Kit forms, GPS coordinates and plot photographs support data quality and traceability, while continued training strengthens implementation. In 2024 and 2025, 426 Yellow, Red Mottled and Large Red bean genotypes were tested over two seasons across 309 farmer-managed sites in Tanzania’s Northern Highlands, Southern Highlands and Lake Region. In 2026, a new cohort of 575 Yellow bean genotypes was tested across 503 farmer-managed fields in the same Tanzanian regions and in Kenya, supported by more than 50 extension officers. The methodological evaluation examines trial retention, data completeness, timeliness, workload, costs, agreement between farmer and extension assessments, and consistency between on-farm and on-station performance. It also tests whether combining on-farm and on-station evidence can improve selection accuracy and expected genetic gain. The platform provides a framework for testing whether earlier farmer input and agronomic learning can strengthen selection, shorten the breeding cycle from 7–10 years to 3–4 years, and support more inclusive, demand-driven crop improvement.

Keywords: Adoption, common bean, extension, farmer-managed trials, farmer preference, genetic gain, participatory breeding, smallholders

Contact Address: Julius Kwesiga, The Alliance of Bioversity International & CIAT, c/o ICIPE Duduville Campus, Nairobi, Kenya, e-mail: j.kwesigacgiar.org