Browsing by Author "Bigirwa, George"

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    Comparison of Response to Nitrogen between Upland NERICAs and ITA (Oryza sativa) Rice Varieties
    (Journal of Agricultural Science, 2012) Onaga, Geoffrey; Asea, Godfrey; Lamo, Jimmy; Kikafunda, Joseph; Bigirwa, George
    Average yields of upland rice are the lowest in Uganda, and most of the productivity gains attributed to improved varieties are related to increased area of production from clearing virgin lands for rice production. In a bid to optimize productivity, we compared the effect of four nitrogen fertilizer treatments: 0, 40, 80 and 120 kgN/ha and two variety types (ITAs (Oryza sativa) and NERICAs (New rice for Africa)) on grain yield and yield parameters in four locations. Combined analysis of variance revealed that nitrogen fertilizer increased mean grain yields from 2116-5200 kg/ha in the NERICAs and 2331-5100 kg/ha in the ITAs. In all the study areas, NERICA 4 and NARIC 2 outperformed NARIC 1 and NERICA 1, and yield trends were consistent over the years suggesting that the two varieties respond better to N fertilizer application. However, the productivity gains are probably related to genetic potential of the varieties rather than the N fertilizer effect, as reflected by the consistent relative performance between 0 N and other N rates. The heavier grains of NARIC 2 and NERICA 4 suggest greater dry matter accumulation before heading, as these varieties have a longer period of vegetative growth. The significant interaction of location x fertilizer and location x variety reveals the need for evaluating the nitrogen-supplying power of soils in the various cropping systems in the country.
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    Sustainable Farming in Practice: Building Resilient and Profitable Smallholder Agricultural Systems in Sub-Saharan Africa
    (Sustainability, 2023) Amede, Tilahun; Konde, Aggie Asiimwe; Muhinda, Jean Jacques; Bigirwa, George
    Sub-Saharan Africa is at crossroads. With a rapidly growing population of 1.2 billion and changing climates, the continent faces major development challenges, including food insecurity, climate change, resource degradation, poverty, gender inequality, and social exclusion. While there are multiple competing narratives promoted in the high-input, industrialised world to address climate change and the resilience of agricultural systems (e.g., regenerative agriculture, agroecology), there is an ongoing debate and genuine questions about the appropriateness of these approaches to small-scale farmers in SSA. African agricultural systems are unique, characterised by low productivity, nutrient mining, land degradation, hoe culture, and fragmented and diversified small farms. Though environmental pollution and over-dependence on fossil fuel-powered mechanisation are rarely topping the priority list, climate change is becoming a major concern. The top-down narratives from environment-concerned communities lack the tools to address the most pressing and immediate challenge of local communities in Sub-Saharan Africa, namely (i) intensification by increased crop productivity per unit of inputs, (ii) increased access to rural energy forcing farmers to use available biomass for cooking instead of soil regeneration; (iii) the intent of no use or reduced mineral fertilisers, in a system marred by nutrient mining over centuries; and (iv) failure to address recurrent drought through integrated soil water management interventions. To address these specific challenges, we present context-specific, outcome-oriented farming solutions as a viable and appropriate strategy called ‘sustainable farming’. We argue that the nature-based narratives will remain to be important but will be better adopted if they respond to local demands and context-specific challenges of small-scale farmers. By means of three successful land restoration programmes in East Africa, we present eight outcomes that should be addressed to ensure sustainable farming of small holdings and reduce the risk of climate change. For these innovations to be adopted at scale, we proposed to put in place incentive mechanisms and functional last-mile delivery systems.
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    Validation of Consensus Quantitative Trait Loci Associated with Resistance to Multiple Foliar Pathogens of Maize
    (Phytopathology, 2009) Asea, Godfrey; Vivek, Bindiganavile S.; Bigirwa, George; Lipps, Patrick E.; Pratt, Richard C.
    Maize production in sub-Saharan Africa incurs serious losses to epiphytotics of foliar diseases. Quantitative trait loci conditioning partial resistance(rQTL) to infection by causal agents of gray leaf spot (GLS), northern corn leaf blight (NCLB), and maize streak have been reported. Our objectives were to identify simple-sequence repeat (SSR) molecularmarkers linked to consensus rQTL and one recently identified rQTL associated with GLS, and to determine their suitability as tools for selection of improved host resistance. We conducted evaluations of disease severity phenotypes in separate field nurseries, each containing 410 F2:3 families derived from a cross between maize inbred CML202 (NCLB and maize streak resistant) and VP31 (a GLS-resistant breeding line) that possess complimentary rQTL. F2:3 families were selected for resistance based on genotypic (SSR marker), phenotypic, or combined data and the selected F3:4 families were reevaluated. Phenotypic values associated with SSR markers for consensus rQTL in bins 4.08 for GLS, 5.04 for NCLB, and 1.04 for maize streak significantly reduced disease severity in both generations based on single-factor analysis of variance and marker-interval analysis. These results were consistent with the presence of homozygous resistant parent alleles, except in bin 8.06, where markers were contributed by the NCLB-susceptible parent. Only one marker associated with resistance could be confirmed in bins 2.09 (GLS) and 3.06 (NCLB), illustrating the need for more robust rQTL discovery, fine-mapping, and validation prior to undertaking marker-based selection.