Gerald Sebuwufu; Robert Mazur; Mark Westgate; Michael Ugen
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A poster presented at the 2012 Global Pulse Researchers Meeting, Kigali, Rwanda- “Transforming Grain-Legume Systems to Enhance Nutrition and Livelihoods”. Abstract: objectives: Common beans typically yield far less than their potential in Uganda, attributable to poor soil fertility, poor quality seed, and disease. This study evaluated responses of improved bean varieties to N and P application, and determined if P limitation can be overcome in three agroecological zones in Uganda. Methodology: On farm: Varieties K131, Kanyebwa and NABE4 were evaluated at four fertility levels: Control, Farm Yard Manure at 10 T/ha, P at 40 kg/ha), and FYM at 0.5 T/ha plus P at 20 kg/ha. Each trial had 24 plots (7.5 m2) in a randomized block with two reps. Research station: four P rates 0-180 kg/ha were applied at planting. Diseases were scored between flowering and early pod fill according to the CIAT scale. Harvest data included plants per plot, pods per plant, seeds per pod, total yield, clean yield, 100 seed weight, seed moisture Content. Results: Improved varieties produced greater and more stable yields. Fertilizer treatments increased yield, but remained far short of potential. Preliminary analysis of yield response to P showed no significant effects up to 180 kg/ha. Low average yields, 495-1035 kg/ha, were associated with very low plant densities (3-14 pl/m2). Intercropping did not increase yield over monoculture. Angular Leaf Spot, Common Bacterial Blight and Flowery Leaf Spot severity were not related to P fertility. Significance: The Goal of doubling bean yields on nutrient depleted soils will not be achieved simply by replenishing soil macronutrients. On-farm management that integrates high quality seed, establishes vigorous plant stands, promotes nodulation, and maintains optimum plant population densities is essential.