Abstract

Common bean (Phaseolus vulgaris L.) is the most important grain legume in Uganda. Beans managed under conventional systems range in yield from 500 to 800 kg ha^-1, with a yield gap of about 75%. The objective of this study was to compare the productivity and net profitability of four bean cultivars grown under three management systems on Phaeozem soil (Mollisol) in Masaka District, Uganda. The experimental design was a randomized incomplete block in a split-plot arrangement. Management system was the whole-plot factor and included the Conventional Farmer (CFS), Improved Farmer (IFS), and High Input systems (HIS). Management systems differed for seed fungicide treatment (no vs. yes), seeding density (10 vs. 20 seed m^-2), plant configuration (scatter vs. rows), fertilizer applications (P, K, Ca, and Mg), rhizobium inoculation (no vs. yes), pesticide applications (no vs. yes), and frequency and timing of weeding. Subplots were four common bean cultivars selected for varying resistance to foliar pathogens. Increasing management intensity and planting cultivars tolerant to common bean diseases improved bean grain yield. Mean grain yield was greater in HIS than IFS and CFS. For all management systems, disease resistant NABE 14 produced more grain yield than NABE 15, K132, and NABE 4. The HIS with NABE 14 produced the most grain (1772 kg ha^-1), most likely due to its greater resistance to angular leaf spot, bean common mosaic virus, and root rot. The economic return to labor and management was greatest for HIS with NABE 14 ($559 ha^-1). Many management system × cultivar combinations resulted in a net loss in the 2015A season, except for NABE 14. Increased yields and profitability are obtainable when utilizing NABE 14 or other disease resistant varieties under improved management practices with increased inputs.

Key words: Phaseolus vulgaris, soil fertility, crop management systems, improved cultivars, profitability.