Browsing by Author "Turyagyenda, Laban Frank"

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    Changes in leaf lamina shape and size during banana shoot development
    (Journal of Applied Biosciences, 1997) Blomme, Guy; Turyagyenda, Laban Frank; Soka, Geofrey; Swennen, Rony
    Bananas and plantains are grown as perennial crops, producing consecutive generations from suckers, which develop on the main plant. Sucker development consists of distinct physiological stages: peeper (small sucker appearing just above the ground and bearing scale leaves only), sword sucker (large sucker with lanceolate type leaves) and maiden sucker (large non-fruiting sucker with foliage leaves). Peepers, sword suckers and maiden suckers represent a distinct physiological stage in sucker growth with distinct morphological features, the most important being the leaf lamina size. The aim of this study was to assess changes in leaf lamina shape during the growth of lateral shoots and to determine how fast suckers from different genotypes develop broad leaves to manufacture their own food through photosynthesis, and thus reducing their dependency on the parent for nutrients. This can be achieved by determining how fast the sucker leaf length: width ratio halves (i.e. the RL50 value).
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    The Efficiency of Air-Drying Pared Corms of Banana Suckers in Reducing the Risk of Soil-Mediated Xanthomonas Wilt Infections in Ethiopia
    (Tree and Forestry Science and Biotechnology, 2010) Shehabu, Meki; Addis, Temesgen; Turyagyenda, Laban Frank; Alemu, Tamiru; Mekonen, Shiferaw; Blomme, Guy
    Xanthomonas wilt caused by Xanthomonas campestris pv. musacearum is one of the most threatening constraints to banana and enset (Ensete ventricosum) production in Ethiopia. The disease was unknown outside of Ethiopia until it was reported in Uganda in 2001. Since then the disease has spread to many East and Central African countries. Xanthomonas campestris pv. musacearum can only enter a plant through mechanical wounds (e.g. inflicted by garden tools) or natural wounds (e.g. male flower scars). Corm paring is a good practice for the control of weevils and nematode pests in banana but when the practice is conducted and corms planted in Xanthomonas wilt infected fields, Xcm infection occurs. As a solution, curing of corms before planting has been recommended. It is however not known if the recommendation could be adopted in Ethiopia. The study was therefore initiated to evaluate the efficiency of air-drying pared corms of banana suckers in reducing the risk of soil-mediated Xanthomonas Wilt infections under conditions prevailing in Ethiopia. Four treatments, i.e., pared and immediately planted, non-pared and immediately planted, pared and air-dried for three days and non-pared and air-dried for three days were tested for ‘Pisang Awak’ and a ‘Matooke’ genotype in a pot experiment. A total of 30 plants were used for each of the treatments per genotype. The disease incidence was recorded during six months after planting. Samples from dead or wilted plants were collected and plated on a YPSA medium at 28°C to confirm whether the disease symptoms were due to Xanthomonas campestris pv. musacearum. Paring and air-drying of banana suckers before planting increased soil-mediated Xanthomonas wilt infections. To reduce soil-mediated Xanthomonas infections, suckers should be carefully uprooted to avoid wounding and the uprooted suckers should be planted immediately after uprooting.
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    Nutrient limitations regulate soil greenhouse gas fluxes from tropical forests: evidence from an ecosystem-scale nutrient manipulation experiment in Uganda
    (Soil, 2021) Tamale, Joseph; Hüppi, Roman; Griepentrog, Marco; Turyagyenda, Laban Frank; Doetterl, Sebastian; Straaten, Oliver van
    Soil macronutrient availability is one of the abiotic controls that alters the exchange of greenhouse gases (GHGs) between the soil and the atmosphere in tropical forests. However, evidence on the macronutrient regulation of soil GHG fluxes from central African tropical forests is still lacking, limiting our understanding of how these biomes could respond to potential future increases in nitrogen (N) and phosphorus (P) deposition. The aim of this study was to disentangle the regulation effect of soil nutrients on soil GHG fluxes from a Ugandan tropical forest reserve in the context of increasing N and P deposition. Therefore, a large-scale nutrient manipulation experiment (NME), based on 40 m×40 m plots with different nutrient addition treatments (N, P, N + P, and control), was established in the Budongo Central Forest Reserve. Soil carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes were measured monthly, using permanently installed static chambers, for 14 months. Total soil CO2 fluxes were partitioned into autotrophic and heterotrophic components through a root trenching treatment. In addition, soil temperature, soil water content, and nitrates were measured in parallel to GHG fluxes. N addition (N and N + P) resulted in significantly higher N2O fluxes in the transitory phase (0–28 d after fertilization; p<0.01) because N fertilization likely increased soil N beyond the microbial immobilization and plant nutritional demands, leaving the excess to be nitrified or denitrified. Prolonged N fertilization, however, did not elicit a significant response in background (measured more than 28 d after fertilization) N2O fluxes. P fertilization marginally and significantly increased transitory (p=0.05) and background (p=0.01) CH4 consumption, probably because it enhanced methanotrophic activity. The addition of N and P (N + P) resulted in larger CO2 fluxes in the transitory phase (p=0.01), suggesting a possible co-limitation of both N and P on soil respiration. Heterotrophic (microbial) CO2 effluxes were significantly higher than the autotrophic (root) CO2 effluxes (p<0.01) across all treatment plots, with microbes contributing about two-thirds of the total soil CO2 effluxes. However, neither heterotrophic nor autotrophic respiration significantly differed between treatments. The results from this study suggest that the feedback of tropical forests to the global soil GHG budget could be disproportionately altered by increases in N and P availability over these biomes.
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    Root And Shoot Development During the Plant Crop and The First Ratoon of Banana and Plantain (Musa Spp.) With Implications for Perennial Cultivation on Degraded Ultisols in South-Eastern Nigeria.
    (ACORBAT, 2006) Blomme, Guy; Swennen, Rony; Turyagyenda, Laban Frank; Tenkouano, Abdou
    The effect of cycle on root system and shoot development was studied for two crop cycles (plant crop and first ratoon). The study revealed that shoot and root system development declined from the plant crop to the first ratoon for plants grown on degraded Ultisols in south-eastern Nigeria.
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    Soil greenhouse gas fluxes following tropical deforestation for fertilizer-intensive sugarcane cultivation in northwestern Uganda
    (EGU General Assembly, 2022) Tamale, Joseph; van Straaten, Oliver; Hüppi, Roman; Turyagyenda, Laban Frank; Doetter, Sebastian
    Deforestation followed by fertilizer intensive agriculture is widely recognized as a significant contributor to anthropogenic greenhouse gas emissions (GHG), particularly carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). However, empirical studies focusing on soil GHG flux dynamics from deforestation hotspots in the tropics are still limited creating major uncertainties for constraining global GHG budgets. In this study, we investigated how deforestation for fertilizer intensive sugarcane cultivation in Uganda affects soil-borne GHGs. Therefore, soil GHG fluxes were measured in a primary forest and in a completely randomized experiment premised in the neighboring sugarcane fields with different fertilizer regimes, representing both smallholder and industrial-scale sugarcane farm management. Despite the use of different fertilization rates (low, standard, and high) as treatments for the sugarcane CRD experiment, neither auxiliary controls nor soil GHG fluxes significantly differed among the CRD treatments. Soil respiration was higher in the sugarcane than in the forest, which we attribute to the increased autotrophic respiration from the sugarcane's fine root biomass and the likely exposure of the sugarcane's larger soil organic carbon stocks to microbial decomposition through ploughing operations. The forest soils were a stronger net sink of CH4 than the sugarcane soils despite forest soils having both higher bulk densities and larger water-filled pore space (WFPS), and we suspect that this was due to alteration of the methanotroph abundance upon the conversion. Soil N2O emissions were smaller in the sugarcane than in the forest, which was surprising, but most likely resulted from the excess N being lost either through leaching or uptake by the sugarcane crop. Only seasonal variability in WFPS, among the auxiliary controls, affected CH4 uptake at both sites and soil CO2 effluxes in the sugarcane. Noteworthy, soil N2O fluxes from both sites were unaltered by the seasonality-mediated changes in auxiliary controls. All the findings put together suggest that forest conversion for sugarcane cultivation alters soil GHG fluxes by increasing soil CO2 emissions and reducing both soil CH4 sink strength and soil N2O emissions.