Kumi District is one of the major sweet potato growing area of Uganda, and the crop is grown both... more Kumi District is one of the major sweet potato growing area of Uganda, and the crop is grown both as a cash crop and for food security. Although sweet potato is very important in the food system, little documentation on the production, storage, processing and marketing is available for the area. To explore the current role of sweet potato in the specific farming system of Kumi and identify socio-economic constraints affecting the production, processing and marketing, we conducted a survey in 120 households of Kumi Sub-County using informal and formal questionnaires. The results indicated the adequacy of farmers’ cultural practices in the production of sweet potato. Cultivar Tanzania was found being monoculturally grown in each household of Kumi Sub-County. Major sweet potato production constraints were related to high labor cost and inadequacy of availing the planting material after the long dry season. Expanded use of simple rapid multiplication techniques and the feasibility of ef...
Mudiope J., D. L. Coyne, E. Adipala and H. A. L. Talwana. 2012. Damage to yam (Dioscorea spp.) by... more Mudiope J., D. L. Coyne, E. Adipala and H. A. L. Talwana. 2012. Damage to yam (Dioscorea spp.) by root-knot nematode (Meloidogyne spp.) under field and storage conditions in Uganda. Nematropica 42:137-145. Although root-knot nematodes (Meloidogyne spp.) are a widely distributed pest of yam (Dioscorea spp.), the level of damage the yams incur, either alone or in association with other plant-parasitic nematodes is largely undetermined. The current study assessed the damage Meloidogyne spp. caused in the field and during storage, following inoculation onto clean seed material and also to yam planted into infested fields. In general, Meloidogyne spp. caused little galling to roots and tubers, and limited reduction in plant growth and yield. Of three species tested, D. rotundata was the most susceptible and most heavily affected by Meloidogyne spp. infection, D. alata was the least affected, and D. cayenensis was intermediately affected yam species. Meloidogyne spp. infection of tubers s...
Progress in pest management on cassava (Manihot esculenta) in Africa has witnessed remarkable ach... more Progress in pest management on cassava (Manihot esculenta) in Africa has witnessed remarkable achievements over recent years in the management of African cassava mosaic virus, cassava mealy bug, cassava green mite and overall germplasm improvement for yield improvements. From the scant information available, root-knot nematodes appear to pose potentially serious constraints to cassava production across Africa. Under heavy infection, 98 % yield losses have been reported and in a survey in Uganda, 100 % of fields observed were infected, yet little attention has been paid to this potential constraint. On yam (Dioscorea spp.), the yam nematode, Scutellonema bradys, is a primary constraint to production and increased adoption of the crop in West Africa. In East Africa the importance of yam has declined over the last few decades and efforts to increase its promotion are hampered by nematode pests. S. bradys has to date not been observed in East Africa, but Pratylenchus sudanensis has been identified, causing similar damage to S. bradys. Meloidogyne spp. also appear to be particularly damaging to introduced, high-yielding yam lines. Screening against these nematodes is currently in progress. Research at the IITA in East and West Africa has made progress towards improved knowledge on these pests. These include initiating work on the biology and epidemiology of P. sudanensis on yam, improving our knowledge of Meloidogyne spp. important on cassava, expanding information on the distribution and incidence of nematode pests on these crops and development of management options against them
The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color s... more The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color su(3) gauge theory, is formulated in the functional Schrödinger picture with a Gaussian wave functional approximation. The equations of motion for the quantum gauge fields are formulated in the Liouville-von Neumann form. This variational approach is applied in order to derive the transport coefficients, such as the shear viscosity, for the pure gluonic matter by using the linear response theory. As a result, the contribution to the shear viscosity from the quantum gluons is zero up to the lowest order of the coupling g in the quantum gluonic matter.
The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color s... more The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color su(3) gauge theory, is formulated in the functional Schrödinger picture with a Gaussian wave functional approximation. The equations of motion for the quantum gauge fields are formulated in the Liouville-von Neumann form. This variational approach is applied in order to derive the transport coefficients, such as the shear viscosity, for the pure gluonic matter by using the linear response theory. As a result, the contribution to the shear viscosity from the quantum gluons is zero up to the lowest order of the coupling g in the quantum gluonic matter.
In this chapter, we show how the current crop areas under three key staples—rice, maize, and bean... more In this chapter, we show how the current crop areas under three key staples—rice, maize, and beans—could be better aligned with the crop suitabilities that are inherent in the East African Community (EAC) region, through some key policy interventions. We take a multi-market model that was constructed for the 5 main countries in the EAC and use it to demonstrate how reducing transport costs, and increasing crop productivities can lead to market-level welfare improvements, as well as a closer alignment between the areas where the crops are cultivated, and the areas with the best agronomic suitability for those crops. At present, a significant proportion of those staples are grown in areas with limited growth potential, but opening up markets in combination with productivity-focused investments can allow countries to make better use of the crop potential they already have, and take advantage of regional market opportunities.
Background: In Sub-Saharan Africa, 40% of children under five years in age are chronically undern... more Background: In Sub-Saharan Africa, 40% of children under five years in age are chronically undernourished. As new investments and attention galvanize action on African agriculture to reduce hunger, there is an urgent need for metrics that monitor agricultural progress beyond calories produced per capita and address nutritional diversity essential for human health. In this study we demonstrate how an ecological tool, functional diversity (FD), has potential to address this need and provide new insights on nutritional diversity of cropping systems in rural Africa. Methods and Findings: Data on edible plant species diversity, food security and diet diversity were collected for 170 farms in three rural settings in Sub-Saharan Africa. Nutritional FD metrics were calculated based on farm species composition and species nutritional composition. Iron and vitamin A deficiency were determined from blood samples of 90 adult women. Nutritional FD metrics summarized the diversity of nutrients provided by the farm and showed variability between farms and villages. Regression of nutritional FD against species richness and expected FD enabled identification of key species that add nutrient diversity to the system and assessed the degree of redundancy for nutrient traits. Nutritional FD analysis demonstrated that depending on the original composition of species on farm or village, adding or removing individual species can have radically different outcomes for nutritional diversity. While correlations between nutritional FD, food and nutrition indicators were not significant at household level, associations between these variables were observed at village level. Conclusion: This study provides novel metrics to address nutritional diversity in farming systems and examples of how these metrics can help guide agricultural interventions towards adequate nutrient diversity. New hypotheses on the link between agro-diversity, food security and human nutrition are generated and strategies for future research are suggested calling for integration of agriculture, ecology, nutrition, and socio-economics.
In this chapter, we show how the current crop areas under three key staples—rice, maize, and bean... more In this chapter, we show how the current crop areas under three key staples—rice, maize, and beans—could be better aligned with the crop suitabilities that are inherent in the East African Community (EAC) region, through some key policy interventions. We take a multi-market model that was constructed for the 5 main countries in the EAC and use it to demonstrate how reducing transport costs, and increasing crop productivities can lead to market-level welfare improvements, as well as a closer alignment between the areas where the crops are cultivated, and the areas with the best agronomic suitability for those crops. At present, a significant proportion of those staples are grown in areas with limited growth potential, but opening up markets in combination with productivity-focused investments can allow countries to make better use of the crop potential they already have, and take advantage of regional market opportunities.
1 The Earth Institute at Columbia University, New York, NY, USA 2 Leuven Sustainable Earth Resear... more 1 The Earth Institute at Columbia University, New York, NY, USA 2 Leuven Sustainable Earth Research Center at Katholieke Universiteit Leuven, Leuven, Belgium 3 Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland 4 Division of Research and Development, CATIE, Turrialba, Costa Rica 5 World Agroforestry Centre, The Sauri Millennium Villages Cluster, Kisumu, Kenya 6 Bioversity International, Rome, Italy 7 Department of Earth and Environmental Sciences at Katholieke Universiteit Leuven, Leuven, Belgium 8The United Nations Development Program, The Ruhiira Millennium Villages Cluster, Mbarara, Uganda 9 The Millennium Development Goals Centre for East and Southern Africa, Nairobi, Kenya 10 The United Nations Development Program, The Mwandama Millennium Villages Cluster, Zomba, Malawi * These authors contributed equally to this work. This paper is adapted from Remans et al. 2011 Assessing nutritional diversity of cropping systems in African ...
ABSTRACT There are a growing number of initiatives that aim to increase fertilizer use in many pa... more ABSTRACT There are a growing number of initiatives that aim to increase fertilizer use in many parts of sub-Saharan Africa in support of the African Green Revolution. Numerous reports indicate a high variability in yields within and between farms; this could affect the crop’s response to fertilizers and therefore their efficiency. Such variability has been attributed to existence of a soil fertility gradient, resulting from differences in resource allocation associated with management strategies. Other biophysical characteristics beyond management, such as soil physical and chemical properties, topography and other environmental attributes could play a major role in this variability. Understanding the determinants of this variability could be a step forward in predicting response to fertilizers and establishing guidelines on efficient use of fertilizers tailored to specific locations. Multi-location nutrient omission trials were conducted in 16 fields distributed with a 10km x 10km grid in southwestern Uganda to determine the importance of individual major nutrients and of micronutrients for maize production as a way to identify appropriate fertilizers adapted to the area. A total of 10 treatments were run per field: a Control treatment with no nutrients added, a treatment with the application of the 3 major nutrients N, P, and K (NPK treatment), 3 treatments in which N, P, and K were omitted from NPK treatment one at a time, a treatment with S added to NPK, a treatment with multinutrients (Ca, Mg, S, micronutrients) in addition to NPK, 2 treatments in which K is not applied but S or S and Zn were added, and a treatment in which lime is added to NPK. Maize yields in the control treatment were highly variable between the various fields, ranging from below 1Mg ha-1 to 6 Mg ha-1. The response to the combination of N,P and K, representing common fertilizers used in Africa, varied between fields, with 7 fields showing little or no response. We link the soil parameters and environmental attributes to yield data to understand the major determinants of variability in control yields and in the maize crop’s response of fertilizers. Major reasons for the observed non-responsiveness to fertilizers are discussed.
Yams ( Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunatel... more Yams ( Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunately, nematodes are major pests to their production. A study was undertaken in major yam growing areas of Uganda to investigate the association of plant parasitic nematodes with damage symptoms. Nematodes were assessed from tubers, roots and surrounding soil for seven cultivars belonging to Dioscorea alata , D. bulbisiana , D. burkilliana and D. cayenensis at harvest. Pratylenchus sudanensis was found in the greatest density and was followed by Meloidogyne spp. Higher densities of both nematodes were observed in the tubers rather than roots. Although symptoms of cracking and galling were relatively low, P. sudanensis incidence was strongly associated with cracking and Meloidogyne spp. with galling. Pratylenchus sudanensis and Meloidogyne spp. incidence their associated damage were, however, negatively correlated, suggesting inter-species competition. Principal components analysis of data su...
Historically, agricultural systems have been assessed on the basis of a narrow range of criteria,... more Historically, agricultural systems have been assessed on the basis of a narrow range of criteria, such as profitability or yields. Yet, these metrics do not reflect the diversity of nutrients provided by the system that is critical for human health. In this study we take a step to demonstrate how ecological tools can play a role in addressing nutritional diversity as an overlooked ecosystem service of agricultural systems.
We propose a novel indicator measuring one dimension of the sustainability of an entity in modern... more We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, Nneutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US$ 3050 was collected from the participants and used to offset the conference's N footprint by supporting the UN Millennium Village cluster Ruhiira in SouthWestern Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates.
Sterile carrot disks have been used successfully for monoxenic culture of root lesion nematodes s... more Sterile carrot disks have been used successfully for monoxenic culture of root lesion nematodes such as Pratylenchus brachyurus (Moody et al., 1973) and P. vulnus (Townson & Lear, 1982), and excised maize roots have been used to rear P. penetrans (Tiner, 1960) and P. zeae (Jordaan & De Waele, 1988). Recent reports have indicated that P. sudanensis is causing damage to yams (Dioscorea spp.) in Uganda (Mudiope, 1999; Coyne et al., 2003). Information on the biology and epidemiology of P. sudanensis is very limited. It has been associated with over 20 plant species in Sudan, however, where it is viewed as an economically damaging pest of cotton (Saadabi, 1985). Other favourable hosts included sorghum, pigeon pea and lubia bean. Wheat and groundnut were viewed as non-hosts. In order to investigate further the biology of this nematode, a readily available source of nematode cultures would be needed. Therefore, sterile carrot disk and excised maize root methods were assessed for their ability to support mass culture of P. sudanensis. Materials and methods Three separate geographical populations of P. sudanensis from Rakai, Masaka and Jinja Districts, Uganda, were used in the study, all originating from yam roots and tubers. The districts all border Lake Victoria, are at similar altitudes (approx 1500 m above sea level) and are in relatively close proximity to each other. For each isolate,
Kumi District is one of the major sweet potato growing area of Uganda, and the crop is grown both... more Kumi District is one of the major sweet potato growing area of Uganda, and the crop is grown both as a cash crop and for food security. Although sweet potato is very important in the food system, little documentation on the production, storage, processing and marketing is available for the area. To explore the current role of sweet potato in the specific farming system of Kumi and identify socio-economic constraints affecting the production, processing and marketing, we conducted a survey in 120 households of Kumi Sub-County using informal and formal questionnaires. The results indicated the adequacy of farmers’ cultural practices in the production of sweet potato. Cultivar Tanzania was found being monoculturally grown in each household of Kumi Sub-County. Major sweet potato production constraints were related to high labor cost and inadequacy of availing the planting material after the long dry season. Expanded use of simple rapid multiplication techniques and the feasibility of ef...
Mudiope J., D. L. Coyne, E. Adipala and H. A. L. Talwana. 2012. Damage to yam (Dioscorea spp.) by... more Mudiope J., D. L. Coyne, E. Adipala and H. A. L. Talwana. 2012. Damage to yam (Dioscorea spp.) by root-knot nematode (Meloidogyne spp.) under field and storage conditions in Uganda. Nematropica 42:137-145. Although root-knot nematodes (Meloidogyne spp.) are a widely distributed pest of yam (Dioscorea spp.), the level of damage the yams incur, either alone or in association with other plant-parasitic nematodes is largely undetermined. The current study assessed the damage Meloidogyne spp. caused in the field and during storage, following inoculation onto clean seed material and also to yam planted into infested fields. In general, Meloidogyne spp. caused little galling to roots and tubers, and limited reduction in plant growth and yield. Of three species tested, D. rotundata was the most susceptible and most heavily affected by Meloidogyne spp. infection, D. alata was the least affected, and D. cayenensis was intermediately affected yam species. Meloidogyne spp. infection of tubers s...
Progress in pest management on cassava (Manihot esculenta) in Africa has witnessed remarkable ach... more Progress in pest management on cassava (Manihot esculenta) in Africa has witnessed remarkable achievements over recent years in the management of African cassava mosaic virus, cassava mealy bug, cassava green mite and overall germplasm improvement for yield improvements. From the scant information available, root-knot nematodes appear to pose potentially serious constraints to cassava production across Africa. Under heavy infection, 98 % yield losses have been reported and in a survey in Uganda, 100 % of fields observed were infected, yet little attention has been paid to this potential constraint. On yam (Dioscorea spp.), the yam nematode, Scutellonema bradys, is a primary constraint to production and increased adoption of the crop in West Africa. In East Africa the importance of yam has declined over the last few decades and efforts to increase its promotion are hampered by nematode pests. S. bradys has to date not been observed in East Africa, but Pratylenchus sudanensis has been identified, causing similar damage to S. bradys. Meloidogyne spp. also appear to be particularly damaging to introduced, high-yielding yam lines. Screening against these nematodes is currently in progress. Research at the IITA in East and West Africa has made progress towards improved knowledge on these pests. These include initiating work on the biology and epidemiology of P. sudanensis on yam, improving our knowledge of Meloidogyne spp. important on cassava, expanding information on the distribution and incidence of nematode pests on these crops and development of management options against them
The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color s... more The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color su(3) gauge theory, is formulated in the functional Schrödinger picture with a Gaussian wave functional approximation. The equations of motion for the quantum gauge fields are formulated in the Liouville-von Neumann form. This variational approach is applied in order to derive the transport coefficients, such as the shear viscosity, for the pure gluonic matter by using the linear response theory. As a result, the contribution to the shear viscosity from the quantum gluons is zero up to the lowest order of the coupling g in the quantum gluonic matter.
The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color s... more The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color su(3) gauge theory, is formulated in the functional Schrödinger picture with a Gaussian wave functional approximation. The equations of motion for the quantum gauge fields are formulated in the Liouville-von Neumann form. This variational approach is applied in order to derive the transport coefficients, such as the shear viscosity, for the pure gluonic matter by using the linear response theory. As a result, the contribution to the shear viscosity from the quantum gluons is zero up to the lowest order of the coupling g in the quantum gluonic matter.
In this chapter, we show how the current crop areas under three key staples—rice, maize, and bean... more In this chapter, we show how the current crop areas under three key staples—rice, maize, and beans—could be better aligned with the crop suitabilities that are inherent in the East African Community (EAC) region, through some key policy interventions. We take a multi-market model that was constructed for the 5 main countries in the EAC and use it to demonstrate how reducing transport costs, and increasing crop productivities can lead to market-level welfare improvements, as well as a closer alignment between the areas where the crops are cultivated, and the areas with the best agronomic suitability for those crops. At present, a significant proportion of those staples are grown in areas with limited growth potential, but opening up markets in combination with productivity-focused investments can allow countries to make better use of the crop potential they already have, and take advantage of regional market opportunities.
Background: In Sub-Saharan Africa, 40% of children under five years in age are chronically undern... more Background: In Sub-Saharan Africa, 40% of children under five years in age are chronically undernourished. As new investments and attention galvanize action on African agriculture to reduce hunger, there is an urgent need for metrics that monitor agricultural progress beyond calories produced per capita and address nutritional diversity essential for human health. In this study we demonstrate how an ecological tool, functional diversity (FD), has potential to address this need and provide new insights on nutritional diversity of cropping systems in rural Africa. Methods and Findings: Data on edible plant species diversity, food security and diet diversity were collected for 170 farms in three rural settings in Sub-Saharan Africa. Nutritional FD metrics were calculated based on farm species composition and species nutritional composition. Iron and vitamin A deficiency were determined from blood samples of 90 adult women. Nutritional FD metrics summarized the diversity of nutrients provided by the farm and showed variability between farms and villages. Regression of nutritional FD against species richness and expected FD enabled identification of key species that add nutrient diversity to the system and assessed the degree of redundancy for nutrient traits. Nutritional FD analysis demonstrated that depending on the original composition of species on farm or village, adding or removing individual species can have radically different outcomes for nutritional diversity. While correlations between nutritional FD, food and nutrition indicators were not significant at household level, associations between these variables were observed at village level. Conclusion: This study provides novel metrics to address nutritional diversity in farming systems and examples of how these metrics can help guide agricultural interventions towards adequate nutrient diversity. New hypotheses on the link between agro-diversity, food security and human nutrition are generated and strategies for future research are suggested calling for integration of agriculture, ecology, nutrition, and socio-economics.
In this chapter, we show how the current crop areas under three key staples—rice, maize, and bean... more In this chapter, we show how the current crop areas under three key staples—rice, maize, and beans—could be better aligned with the crop suitabilities that are inherent in the East African Community (EAC) region, through some key policy interventions. We take a multi-market model that was constructed for the 5 main countries in the EAC and use it to demonstrate how reducing transport costs, and increasing crop productivities can lead to market-level welfare improvements, as well as a closer alignment between the areas where the crops are cultivated, and the areas with the best agronomic suitability for those crops. At present, a significant proportion of those staples are grown in areas with limited growth potential, but opening up markets in combination with productivity-focused investments can allow countries to make better use of the crop potential they already have, and take advantage of regional market opportunities.
1 The Earth Institute at Columbia University, New York, NY, USA 2 Leuven Sustainable Earth Resear... more 1 The Earth Institute at Columbia University, New York, NY, USA 2 Leuven Sustainable Earth Research Center at Katholieke Universiteit Leuven, Leuven, Belgium 3 Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland 4 Division of Research and Development, CATIE, Turrialba, Costa Rica 5 World Agroforestry Centre, The Sauri Millennium Villages Cluster, Kisumu, Kenya 6 Bioversity International, Rome, Italy 7 Department of Earth and Environmental Sciences at Katholieke Universiteit Leuven, Leuven, Belgium 8The United Nations Development Program, The Ruhiira Millennium Villages Cluster, Mbarara, Uganda 9 The Millennium Development Goals Centre for East and Southern Africa, Nairobi, Kenya 10 The United Nations Development Program, The Mwandama Millennium Villages Cluster, Zomba, Malawi * These authors contributed equally to this work. This paper is adapted from Remans et al. 2011 Assessing nutritional diversity of cropping systems in African ...
ABSTRACT There are a growing number of initiatives that aim to increase fertilizer use in many pa... more ABSTRACT There are a growing number of initiatives that aim to increase fertilizer use in many parts of sub-Saharan Africa in support of the African Green Revolution. Numerous reports indicate a high variability in yields within and between farms; this could affect the crop’s response to fertilizers and therefore their efficiency. Such variability has been attributed to existence of a soil fertility gradient, resulting from differences in resource allocation associated with management strategies. Other biophysical characteristics beyond management, such as soil physical and chemical properties, topography and other environmental attributes could play a major role in this variability. Understanding the determinants of this variability could be a step forward in predicting response to fertilizers and establishing guidelines on efficient use of fertilizers tailored to specific locations. Multi-location nutrient omission trials were conducted in 16 fields distributed with a 10km x 10km grid in southwestern Uganda to determine the importance of individual major nutrients and of micronutrients for maize production as a way to identify appropriate fertilizers adapted to the area. A total of 10 treatments were run per field: a Control treatment with no nutrients added, a treatment with the application of the 3 major nutrients N, P, and K (NPK treatment), 3 treatments in which N, P, and K were omitted from NPK treatment one at a time, a treatment with S added to NPK, a treatment with multinutrients (Ca, Mg, S, micronutrients) in addition to NPK, 2 treatments in which K is not applied but S or S and Zn were added, and a treatment in which lime is added to NPK. Maize yields in the control treatment were highly variable between the various fields, ranging from below 1Mg ha-1 to 6 Mg ha-1. The response to the combination of N,P and K, representing common fertilizers used in Africa, varied between fields, with 7 fields showing little or no response. We link the soil parameters and environmental attributes to yield data to understand the major determinants of variability in control yields and in the maize crop’s response of fertilizers. Major reasons for the observed non-responsiveness to fertilizers are discussed.
Yams ( Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunatel... more Yams ( Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunately, nematodes are major pests to their production. A study was undertaken in major yam growing areas of Uganda to investigate the association of plant parasitic nematodes with damage symptoms. Nematodes were assessed from tubers, roots and surrounding soil for seven cultivars belonging to Dioscorea alata , D. bulbisiana , D. burkilliana and D. cayenensis at harvest. Pratylenchus sudanensis was found in the greatest density and was followed by Meloidogyne spp. Higher densities of both nematodes were observed in the tubers rather than roots. Although symptoms of cracking and galling were relatively low, P. sudanensis incidence was strongly associated with cracking and Meloidogyne spp. with galling. Pratylenchus sudanensis and Meloidogyne spp. incidence their associated damage were, however, negatively correlated, suggesting inter-species competition. Principal components analysis of data su...
Historically, agricultural systems have been assessed on the basis of a narrow range of criteria,... more Historically, agricultural systems have been assessed on the basis of a narrow range of criteria, such as profitability or yields. Yet, these metrics do not reflect the diversity of nutrients provided by the system that is critical for human health. In this study we take a step to demonstrate how ecological tools can play a role in addressing nutritional diversity as an overlooked ecosystem service of agricultural systems.
We propose a novel indicator measuring one dimension of the sustainability of an entity in modern... more We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, Nneutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US$ 3050 was collected from the participants and used to offset the conference's N footprint by supporting the UN Millennium Village cluster Ruhiira in SouthWestern Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates.
Sterile carrot disks have been used successfully for monoxenic culture of root lesion nematodes s... more Sterile carrot disks have been used successfully for monoxenic culture of root lesion nematodes such as Pratylenchus brachyurus (Moody et al., 1973) and P. vulnus (Townson & Lear, 1982), and excised maize roots have been used to rear P. penetrans (Tiner, 1960) and P. zeae (Jordaan & De Waele, 1988). Recent reports have indicated that P. sudanensis is causing damage to yams (Dioscorea spp.) in Uganda (Mudiope, 1999; Coyne et al., 2003). Information on the biology and epidemiology of P. sudanensis is very limited. It has been associated with over 20 plant species in Sudan, however, where it is viewed as an economically damaging pest of cotton (Saadabi, 1985). Other favourable hosts included sorghum, pigeon pea and lubia bean. Wheat and groundnut were viewed as non-hosts. In order to investigate further the biology of this nematode, a readily available source of nematode cultures would be needed. Therefore, sterile carrot disk and excised maize root methods were assessed for their ability to support mass culture of P. sudanensis. Materials and methods Three separate geographical populations of P. sudanensis from Rakai, Masaka and Jinja Districts, Uganda, were used in the study, all originating from yam roots and tubers. The districts all border Lake Victoria, are at similar altitudes (approx 1500 m above sea level) and are in relatively close proximity to each other. For each isolate,
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