N2Africa seeks applicants for five PhD "sandwich" scholarships available to start in September 2014. We seek candidates with an excellent academic record a strong commitment to advancing science to enhance agricultural productivity of grain legumes in sub-Saharan Africa and their use by smallholder farmers. All students will register for their PhD at Wageningen University. Preference will be given to candidates who are employed by a national university or research institute in the country specified for each of the PhD scholarships.
1. Tanzania
Intensification of common bean cultivation on smallholder farms in the Northern Highlands of Tanzania
Common bean is a staple crop and an important source of dietary protein for the rural poor in the Northern Highlands of Tanzania. High yielding improved bean varieties (both climbers and bushy types) are strategic crops to mitigate recurring hunger and poverty. With the ability to fix atmospheric nitrogen, common bean has the potential to boost productivity of the associated crops and to sustainably intensify the larger cropping system. Yields and the amount of nitrogen fixed depend on the interaction between (GL x GR) x E x M, where: GL = legume genotype, GR = rhizobial strain, E = environment and M = management.
Although the potential productivity of common bean, especially of new improved varieties, is high (3 t ha-1), farmers often obtain yields far below this potential (0.3 – 1 t ha-1). Farmers in this area usually cultivate common bean as intercrop or in rotation with maize, using traditional planting methods. Generally, management levels are low, with limited use of mineral fertilizers, poor seed quality and non-optimal weeding. In addition, the climate is highly variable and the lands on which common beans are planted are often marginal lands, limited in available soil nitrogen. How the multiple factors included in the (GL x GR) x E x M interaction exactly contribute to bean yield and the amount of nitrogen fixed and how those factors interact with each other is poorly understood.
The proposed research will focus to unravel the contributions of genetic, management and environment related factors to common bean yield and nitrogen fixation, including cultural, social and economic analyses of growing common beans. The generated knowledge will contribute to sustainable intensification of cropping systems in the Northern Highlands of Tanzania.
Scholarship requirements
You have an MSc in agro-ecology, land use studies, agronomy, soil science or another topic that suits you to work on systems analysis and integration. You wish to work closely with others in a team and have a strong motivation to pursue a PhD. You have good communication skills. This scholarship is open for Tanzanian nationals.
2. Uganda
Understanding the need for inoculation of common bean in smallholder farming in Uganda
Common bean is a staple crop and an important source of dietary protein for the rural poor in the highlands of Uganda. A number of new bush and climbing bean varieties have been released with improved pest and disease resistance and better yields than the varieties commonly grown. Climbing bean varieties offer an option for farmers with small areas of land to intensify their production due to their superior yield potential compared with bush types. Research conducted during the first phase of N2Africa indicated highly variable responses to inoculation in common bean – often no significant differences, sometimes strong responses in yield. Common bean is known to nodulate with a wide diversity of fast-growing rhizobia (both strains and species) in African soils. The promiscuous nature of common bean could be one of the reasons for the erratic response to inoculation – sometimes there are many effective rhizobia present in the soil, sometimes the background population is largely ineffective on common bean.
This PhD project will focus on elucidating reasons for the sporadic success of inoculation with common bean. A combination of classical and modern (molecular) microbiology methods will be used to (i) characterize background populations of rhizobia found in Ugandan soils (the so-called indigenous rhizobia), (ii) test the success of elite inoculant strains in establishing themselves against the rhizobial populations present in soils, (iii) test the effectiveness of inoculant strains compared with indigenous strains, (iv) to select new elite rhizobia to identify potential strains for use in inoculants, (v) to test these elite strains in the field, (vi) evaluate competitiveness and survival of introduced rhizobium strains as affected by management and environment.
Scholarship requirements
You have an MSc in microbiology or molecular biology with a thorough understanding of smallholder agriculture. You wish to work closely with others in a team and have a strong motivation to pursue a PhD. You have good communication skills. This scholarship is open for Ugandan nationals.
3. Ethiopia
Understanding host legume x rhizobium strain interactions in common bean and chickpea
The genetic potential of grain legumes (GL) targeted to suitable environments (E) depends on the presence of effective soil populations of rhizobia or inoculation (GR) under appropriate crop and soil management (M). This (GL x GR) x E x M interaction forms the core of the N2Africa approach. Over the past year N2Africa has conducted multi-locational experiments that have confirmed that common bean and chickpea respond strongly when inoculated with elite strains. A diverse collection of common bean and chickpea rhizobia have been isolated and characterized by Hawassa University, Ethiopia. The availability of core genotypes of these two important grain legumes opens new opportunities for understanding host legume genotype x rhizobium strain interactions.
The proposed PhD research will provide detailed molecular characterization of the rhizobium strains that nodulate common bean and those that nodulate chickpea. Glasshouse experiments will be conducted to explore the host-rhizobium interactions in both nodulation (infectiveness) and nitrogen fixation (effectiveness). Once repeated tests have been performed to confirm the best combinations, these will be advanced to field testing. The most effective host x strain combinations will provide a basis for future breeding for enhanced nitrogen fixation in these two important grain crops.
Scholarship requirements
You have an MSc in microbiology or molecular biology with a thorough understanding of smallholder agriculture. You wish to work closely with others in a team and have a strong motivation to pursue a PhD. You have good communication skills. This scholarship is open for Ethiopian nationals.
4. Ghana
Grain legume residues as a livestock feed resource for smallholders in Northern Ghana
Legumes are a key resource for farmers in Sub Saharan Africa (SSA) both for food grains and residues for livestock feed. Livestock production across SSA is in flux and undergoing a process of intensification. In parts of West Africa, cereal and legume residues have changed from being communal resources to being private resources in the last two decades. Residue values are rising and residues are a tradable resource. In Northern Ghana cowpea and groundnut haulms are extensively traded. There is considerable species and varietal variation in legume residue yield and quality. Furthermore, agronomic practices including those being investigated in N2Africa can influence the livestock feed value of legume residues. It is expected that management of haulms (collection, storage, feeding and/or trade) depends on the farming systems’ objectives. Consequently, across a livestock intensification gradient different use of legume residues will be observed and different options for intensified use identified.
In the research proposed here, the influence of intensification on legume residue use within smallholder livestock systems will be investigated. The research will comprise a series of activities as follows:
- Define an livestock intensification gradient, in northern Ghana and focused around existing N2Africa sites.
- Characterize livestock feeding system along the gradient including extent of inclusion of legume residues in livestock diets, prices for legume residues and quality/yield of legume residues.
- Characterize residue management including post-harvest practices and storage practices.
- Assess recent changes in residue use and prices, using farmer recall and secondary data.
- Conduct action research on improved varieties and practices to enhance livestock production along the intensification gradient.
Scholarship requirements
You have an MSc in animal science, agricultural economics or related subject and a thorough understanding of smallholder agriculture. You wish to work closely with others in a team, have a strong motivation to pursue a PhD and good communication skills. This scholarship is open for Ghanaian nationals.
5. Nigeria
Exploring the potential benefits of rhizobium inoculation with cowpea
Promiscuous legumes such as cowpea that nodulate freely with indigenous rhizobia already present in the soil, have rarely been observed to respond to inoculation with rhizobia. Inoculation responses are only found when the elite inoculant strain is substantially more effective in N2-fixation than the indigenous strains, and when the elite inoculant strain can be established on the roots of the grain legume. This is essentially a ‘numbers game’ and high quality inoculants that can deliver large numbers of the inoculant strain on the seed are needed to ensure success. Understanding success of inoculation under such circumstances relies on studies of background populations of indigenous rhizobia and tracing the success of nodulation by the inoculant strains through ‘competition studies’ using molecular typing.
New multi-purpose cowpea varieties with good grain yield, a short growing cycle and drought tolerance and can easily be integrated in mixed cereal-cowpea systems. These short-duration varieties yield in the middle of the growing season (the "hunger season") allowing double cropping. Their short growing period means that they are much more likely to respond to inoculation in the field than the creeping cowpea varieties that take much longer to mature.
This PhD project will explore the opportunities for inoculation of cowpea in Nigeria – the world’s largest cowpea producer. A combination of field, glasshouse and laboratory experiments will be deployed to understand the success of the new elite cowpea strains in nodulating cowpea against background populations of indigenous rhizobia. Both classical rhizobiology methods and new molecular tools will be deployed. The PhD student will support extensive fieldwork that will be conducted through N2Africa to explore the field response to inoculation in the northern Guinea savannah of Nigeria.
Scholarship requirements
You have an MSc in microbiology or molecular biology with a thorough understanding of smallholder agriculture. You wish to work closely with others in a team and have a strong motivation to pursue a PhD. You have good communication skills. This scholarship is open for Nigerian nationals.
Background information on N2Africa is available on www.N2Africa.org. Please submit your applications to Greta van den Brand gretaj.vandenbrand@wur.nl with a copy (cc) to n2africa.office@wur.nl by 31st March 2014.