Climate change, disease dynamics, and breeding responses in common bean (Phaseolus vulgaris L.) production in Tanzania: a systematic review (2005–2025)

Abstract

Common bean ( Phaseolus vulgaris L.) plays a significant role in Tanzanian agriculture, sustaining food security and rural livelihoods for millions of smallholder farmers. However, its production is increasingly jeopardized by climate change and variability, most notably drought, heat stress, and flooding which has intensified both the frequency and severity of devastating diseases and insect pests. This systematic review, conducted in accordance with PRISMA 2020 guidelines, synthesizes findings from 103 peer-reviewed studies published between 2005 and 2025, drawing from leading scientific databases and institutional repositories focused on Tanzania. Results indicate that over 65% of documented disease outbreaks are attributable to climate extremes, which significantly influence pathogen virulence, life cycles, and host vulnerability. Drought was found to correlate with a 30–50% increase in wilt disease incidence, while heat waves accelerated disease progression in approximately one-third of cases with estimated yield loss of up to 40% by 2050. Flooding, though less frequently addressed, was identified as an emerging and insufficiently studied factor in soil- and water-borne diseases. Breeding initiatives in Tanzania have advanced drought, heat tolerance and resistance to diseases, yet more than 70% of programs continue to focus on single-stress resistance, with limited integration of multi-stress or participatory approaches. The adoption of genomic-assisted selection methods remains promising within national breeding efforts. This review underscores the necessity of transitioning toward climate-smart breeding frameworks, integrating multi-stress resilience, robust disease surveillance, and participatory research to enhance the sustainability and productivity of common bean cultivation under changing climatic conditions.