Naliendele Agricultural Research Institute

Mtwara, Tanzania

Naliendele Agricultural Research Institute

Mtwara, Tanzania
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Bredeson J.V.,University of California at Berkeley | Egesi C.N.,National Root Crops Research Institute NRCRI | Esuma W.,National Crops Resources Research Institute NaCCRI | Ezenwaka L.,National Root Crops Research Institute NRCRI | And 37 more authors.
G3: Genes, Genomes, Genetics | Year: 2015

Cassava (Manihot esculenta Crantz) is a major staple crop in Africa, Asia, and South America, and its starchy roots provide nourishment for 800 million people worldwide. Although native to South America, cassava was brought to Africa 400-500 years ago and is now widely cultivated across sub-Saharan Africa, but it is subject to biotic and abiotic stresses. To assist in the rapid identification of markers for pathogen resistance and crop traits, and to accelerate breeding programs, we generated a framework map for M. esculenta Crantz from reduced representation sequencing [genotyping-by-sequencing (GBS)]. The composite 2412-cM map integrates 10 biparental maps (comprising 3480 meioses) and organizes 22,403 genetic markers on 18 chromosomes, in agreement with the observed karyotype. We used the map to anchor 71.9% of the draft genome assembly and 90.7% of the predicted protein-coding genes. The chromosome-anchored genome sequence will be useful for breeding improvement by assisting in the rapid identification of markers linked to important traits, and in providing a framework for genomic selectionenhanced breeding of this important crop. © 2015 International Cassava Genetic Map Consortium (ICGMC).

Kawuki R.S.,National Crops Resources Research Institute NaCRRI | Kawuki R.S.,University of the Free State | Ferguson M.,International Institute Of Tropical Agriculture | Labuschagne M.T.,University of the Free State | And 10 more authors.
Field Crops Research | Year: 2011

An improved understanding of phenotypic variation within cassava germplasm in southern, eastern and central Africa will help to formulate knowledge-based breeding strategies. Thus, the overall objective of this study was to examine the phenotypic variation in cassava germplasm available within six breeding programmes in Africa, namely Uganda, Kenya, Tanzania, Rwanda, Democratic Republic of Congo and Madagascar. In each country, single-row plots were used for assessment of 29 qualitative traits and evaluation of four quantitative traits: root dry matter content (DMC), harvest index (HI), leaf retention (LR) and root cortex thickness. Qualitative traits provided limited discrimination of cassava germplasm. However, differences in DMC, HI, LR and root cortex thickness were observed among the germplasm indicating scope for genetic improvement. Highest average DMC was registered in Uganda (39.3%) and lowest in Tanzania (30.1%), with the elite genotypes having a relatively higher DMC than local genotypes. Highest average HI was observed in Uganda (0.60) and lowest in Kenya (0.32). Cassava genotypes displayed varied root peel thickness (0.34-4.89. mm). This study highlights variation in agronomic traits that could be exploited to increase cassava productivity. © 2011 Elsevier B.V.

Sola P.,International Center for Research in Agroforestry | Ogendo J.O.,Egerton University | Mponda O.,Naliendele Agricultural Research Institute | Kamanula J.F.,Mzuzu University | And 3 more authors.
Food Security | Year: 2014

Pesticides are the major technology used in the management of field and postharvest losses due to pests. There is growing demand for effective alternatives that present low health risks and conserve ecosystems and biological diversity. Pesticidal plants are increasingly used as alternatives where synthetic products are unaffordable, have limited availability or are ineffective. Plant materials, however, are often used inefficiently and their effective use requires optimisation. In Africa wide-scale uptake of pesticidal plants remains limited despite the success of pyrethrum in some countries and other pesticidal plant products in China and India. This is mainly due to lack of data on efficacy and safety, inconsistent efficacy of plant products, the prohibitive cost of registration, and an inadequately developed conventional pesticides sector. Globally, the demand for botanicals is poised to grow due to an increasing shift in consumer demand for safe food, increasing organic farming, lobbying by environmentalists and the increasing pressure from new regulations on internationally traded foods in Europe. These demands can only be met by formalising production, marketing and use of pesticidal plants. This has to be supported by friendly registration procedures, sustainable forest management, propagation and cultivation of pesticidal plants. This paper presents a critical review of the enabling environment required for wide-scale adoption and commercialisation of botanical pesticides in sub-Saharan Africa. We conclude that regulations and protocols for production, marketing and trade need to be reviewed to facilitate the development of the botanicals sector in Africa. © 2014 Springer Science+Business Media Dordrecht and International Society for Plant Pathology.

Kawuki R.S.,National Crops Resources Research Institute NaCRRI | Kawuki R.S.,University of the Free State | Kawuki R.S.,International Institute Of Tropical Agriculture | Herselman L.,University of the Free State | And 14 more authors.
Plant Genetic Resources: Characterisation and Utilisation | Year: 2013

Studies to quantify genetic variation in cassava germplasm, available within the national breeding programmes in Africa, have been limited. Here, we report on the nature and extent of genetic variation that exists within 1401 cassava varieties from seven countries: Tanzania (270 genotypes); Uganda (268); Kenya (234); Rwanda (184); Democratic Republic of Congo (DRC; 177); Madagascar (186); Mozambique (82). The vast majority of these genotypes do not exist within a formal germplasm conservation initiative and were derived from farmers' fields and National Agricultural Research Systems breeding programmes. Genotypes were assayed using 26 simple sequence repeat markers. Moderate genetic variation was observed with evidence of a genetic bottleneck in the region. Some differentiation was observed among countries in both cultivars and landraces. Euclidean distance revealed the pivotal position of Tanzanian landraces in the region, and STRUCTURE analysis revealed subtle and fairly complex relationships among cultivars and among landraces and cultivars analysed together. This is likely to reflect original germplasm introductions, gene flow including farmer exchanges, disease pandemics, past breeding programmes and the introduction of cultivars from the International Institute of Tropical Agriculture - Nigeria. Information generated from this study will be useful to justify and guide a regional cassava genetic resource conservation strategy, to identify gaps in cassava diversity in the region and to guide breeding strategies. Copyright © 2013 NIAB.

Ndyetabula I.L.,Maruku Agricultural Research Institute | Merumba S.M.,Maruku Agricultural Research Institute | Jeremiah S.C.,Ukiriguru Agricultural Research Institute | Kasele S.,Ukiriguru Agricultural Research Institute | And 3 more authors.
Plant Disease | Year: 2016

Cassava brown streak disease (CBSD), caused by cassava brown streak viruses, is recognized as one of the most important plant disease threats to African food security. This study describes the incidence and severity of the different symptom types caused by CBSD, derived from extensive surveys in the country most severely affected by the disease: Tanzania. Total plant incidence and mean root severity of CBSD, recorded from 341 farmers’ fields, were both greater in the Coast Zone (49.5% and 3.05), than in the Lake Zone (32.7% and 2.57). Overall, the differing incidences recorded declined in the following order: total plant incidence (39.1%), plant shoot incidence (33.4%), plant root incidence (19.3%), root incidence (10.5%), and unusable root incidence (5.4%). The much lower-than-anticipated loss due to the root necrosis that is characteristic of CBSD was offset by large reductions of root number in plants expressing foliar symptoms of CBSD (15.7% in the Coast Zone and 5.5% in the Lake Zone). These data suggest that the effects of CBSD on the growth of affected plants are greater than those due to root spoilage. Based on these two factors, annual losses due to CBSD in the parts of Tanzania surveyed were estimated at >860,000 t, equivalent to more than U.S.$51 million. A novel approach to using farm-derived data on the responses of the most frequently cultivated varieties to CBSD infection allowed the grouping of the varieties into four categories, based on their relative resistance or tolerance to infection. This tool should be of value to breeders in identifying and selecting for sources of resistance or tolerance in both local and exotic germplasm, and should ultimately contribute to enhancing the management of one of Africa’s most damaging crop diseases. © 2016 The American Phytopathological Society.

Legg J.P.,IITA Tanzania | Jeremiah S.C.,IITA Tanzania | Jeremiah S.C.,Ukiriguru Agricultural Research Institute LZARDI | Obiero H.M.,Kenya Agricultural Research Institute | And 10 more authors.
Virus Research | Year: 2011

The rapid geographical expansion of the cassava mosaic disease (CMD) pandemic, caused by cassava mosaic geminiviruses, has devastated cassava crops in 12 countries of East and Central Africa since the late 1980s. Region-level surveys have revealed a continuing pattern of annual spread westward and southward along a contiguous 'front'. More recently, outbreaks of cassava brown streak disease (CBSD) were reported from Uganda and other parts of East Africa that had been hitherto unaffected by the disease. Recent survey data reveal several significant contrasts between the regional epidemiology of these two pandemics: (i) severe CMD radiates out from an initial centre of origin, whilst CBSD seems to be spreading from independent 'hot-spots'; (ii) the severe CMD pandemic has arisen from recombination and synergy between virus species, whilst the CBSD pandemic seems to be a 'new encounter' situation between host and pathogen; (iii) CMD pandemic spread has been tightly linked with the appearance of super-abundant Bemisia tabaci whitefly vector populations, in contrast to CBSD, where outbreaks have occurred 3-12 years after whitefly population increases; (iv) the CMGs causing CMD are transmitted in a persistent manner, whilst the two cassava brown streak viruses appear to be semi-persistently transmitted; and (v) different patterns of symptom expression mean that phytosanitary measures could be implemented easily for CMD but have limited effectiveness, whereas similar measures are difficult to apply for CBSD but are potentially very effective. An important similarity between the pandemics is that the viruses occurring in pandemic-affected areas are also found elsewhere, indicating that contrary to earlier published conclusions, the viruses per se are unlikely to be the key factors driving the two pandemics. A diagrammatic representation illustrates the temporal relationship between B. tabaci abundance and changing incidences of both CMD and CBSD in the Great Lakes region. This emphasizes the pivotal role played by the vector in both pandemics and the urgent need to identify effective and sustainable strategies for controlling whiteflies on cassava. © 2011 Elsevier B.V.

Kulembeka H.P.,Ukiriguru Agricultural Research Institute | Ferguson M.,International Institute Of Tropical Agriculture | Herselman L.,University of the Free State | Kanju E.,International Institute Of Tropical Agriculture | And 4 more authors.
Euphytica | Year: 2012

Cassava brown streak disease (CBSD) is an economically important virus disease causing significant losses to cassava root yield and quality in east, central and southern Africa. Breeding for resistance in cassava requires an understanding of the underlying genetic control of CBSD resistance. Sources of CBSD resistance are available but little is known on the value of those varieties as parents for CBSD resistance breeding. Two resistant and two susceptible varieties were crossed in a half diallel design and 35 F 1 progeny from each of the six families, plus parents, were screened at two locations in a randomised complete block design with four replications in warm sub-humid environments of coastal Tanzania in 2008. Screening for CBSD field resistance was done using disease severity scoring on a scale of 1-5. Significant variations in disease severity were observed for crosses, general combining ability (GCA) and specific combining ability (SCA) at both locations. The CBSD shoot symptom severity scores ranged from 1 to 4.4 while root necrosis ranged from 1. 3 to 4.5. The contribution of GCA to the total sum of squares of crosses for disease scores ranged from 86.9 to 95.2 % compared to SCA that ranged from 4.8 to 14.2 %. Additive gene effects were more important than non-additive effects indicating that CBSD resistance is genetically determined and that selection should be successful to improve resistance. Selection of parents with good GCA effects will be important for success in CBSD resistance breeding. © 2012 Springer Science+Business Media B.V.

PubMed | International Institute Of Tropical Agriculture, Naliendele Agricultural Research Institute and Chatham University
Type: Journal Article | Journal: Journal of applied microbiology | Year: 2016

To develop a multiplex TaqMan-based real-time PCR assay (qPCR) for the simultaneous detection and quantification of both RNA and DNA viruses affecting cassava (Manihot esculenta) in eastern Africa.The diagnostic assay was developed for two RNA viruses; Cassava brown streak virus (CBSV) and Uganda cassava brown streak virus (UCBSV) and two predominant DNA viruses; African cassava mosaic virus (ACMV) and East African cassava mosaic virus (EACMV), which cause the economically important cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) respectively. Our method, developed by analysing PCR products of viruses, was highly sensitive to detect target viruses from very low quantities of 4-10 femtograms. Multiplexing did not diminish sensitivity or accuracy compared to uniplex alternatives. The assay reliably detected and quantified four cassava viruses in field samples where CBSV and UCBSV synergy was observed in majority of mixed-infected varieties.We have developed a high-throughput qPCR diagnostic assay capable of specific and sensitive quantification of predominant DNA and RNA viruses of cassava in eastern Africa.The qPCR methods are a great improvement on the existing methods and can be used for monitoring virus spread as well as for accurate evaluation of the cassava varieties for virus resistance.

Kabanza A.K.,Naliendele Agricultural Research Institute | Kabanza A.K.,Catholic University of Leuven | Dondeyne S.,Catholic University of Leuven | Kimaro D.N.,Sokoine University of Agriculture | And 3 more authors.
Zeitschrift fur Geomorphologie | Year: 2013

RUSLE, the revised universal soil loss equation, is widely used for estimating potential soil erosion by water. Field measured model factors are however scarce for tropical regions. We derived RUSLE factors for several soil conservation measures based on three seasons of field plot measurements (2008-2010), in two contrasting landscape units of South Eastern Tanzania, the country's most important cashew growing area. Whereas the derived factors are useful for applying RUSLE in similar environments, this study points to the importance of understanding differences between soil types and landscape units when assessing potential soil erosion. On the Makonde plateau, rainfall erosivity was higher than on the inland plains (7,130 vs 5,783 MJmmha -1 h-1 year-1). The soil erodility K factor was also higher (0.014th MJ-1mm-1) on the sandy Cutanic Acrisols of the Makonde plateau than on the clayey Acric Ferralsols (0.006th MJ-1mm-1) of the inland plains. Likewise, soil loss on the Makonde plateau was much higher than on the inland plain (e. g. for maize 33-127 t ha-1 season-1 vs 3-10 t ha-1 season-1). The differences between the C factor for "maize", and for "maize with crop residues", as well as the differences between the P factors for "lemon grass strips" and "ridges and furrows" indicate that although soils of the Makonde plateau are more susceptible to soil erosion, these soils are also more responsive to soil conservation measures compared to soils of the inland plains. Farmers' local technique of making "ridges and furrows" is particularly effective. Furthermore, the C factors for cashew groves are one order of magnitude lower (0.08-0.09) than for "maize", or for "maize with crop residues" (0.2-0.7), but are still much higher than for "bush fallow" (0.001). Deforestation for agriculture hence bears the risk of increasing soil erosion rates; however, this risk can be minimised by growing cashew trees. © 2013 Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany.

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