Bridging common bean yield gaps through seed adoption using breeder–farmer preferences in Tanzania

The common bean is an important food and cash crop in Tanzania, yet its productivity remains below potential due to limited use of improved seed and continued reliance on informal seed systems. This study reviewed bean seed systems in Tanzania to understand barriers to certified seed adoption, evaluate seed performance, and examine differences between farmer and breeder preferences. A total of 51 studies published between 2000 and 2023 were analyzed. The review found that certified seeds generally outperform farmer-saved seeds, increasing bean yields by approximately 18–25%. However, productivity gains are strongly influenced by fertilizer use and agroecological conditions. High seed costs, limited access to credit, and socio–economic constraints–particularly among women farmers–were identified as major barriers to adoption. Farmers preferred common bean varieties with desirable cooking qualities, taste, storage ability, and adaptability to local environments, whereas breeders emphasized yield potential and disease resistance. This mismatch between breeder priorities and farmer preferences contributes to low adoption of improved varieties. The findings highlight the need for demand–driven breeding approaches, improved access to affordable certified seed, and stronger support systems for smallholder farmers. Strengthening bean seed systems could improve food security, farmer livelihoods, and agricultural sustainability in Tanzania.