Seed System Pathways to Productivity: A Comparative Analysis of Common Bean Seed Classes in Tanzania

Increasing costs of certified common bean seed, coupled with low grain prices, have led farmers to rely more heavily on farm-saved seeds. Understanding the performance of certified, semi-formal, and farmer-saved seed systems is important for improving productivity and guiding seed system development in Tanzania. Field trials were conducted during the 2024/25 season at Lengijave (Arusha), Swaya (Mbeya), and Ihanda (Karagwe District Council). Six certified bean varieties—Lyamungo 90, JESCA, Selian 13, Calima Uyole, Uyole Njano, and Uyole 18—were evaluated using a split-plot design with eight farmer replications per site. Data were analyzed in R version 4.5.1, released 13 June 2025, using Tukey’s HSD test (5%), Principal Component Analysis (PCA), and regression analysis. Significant side effects (p < 0.001) were observed for germination, flowering time, pods per plant, plant height, pod length, seeds per pod, grain yield, and 100-seed weight. Certified seeds consistently produced higher yields and lower variability than semi-formal and farmer-saved seeds. The highest yields were recorded for Uyole Njano Control at Swaya (2437 kg/ha) and Uyole 18 Control at Ihanda (1937 kg/ha), while Lyamungo 90 Control performed well across sites. PCA clearly separated seed classes, confirming the superior performance of certified seeds in enhancing bean productivity in Tanzania.