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

Abstract

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.