Institute des science Agronomiques du Rwanda ISAR

Kigali, Rwanda

Institute des science Agronomiques du Rwanda ISAR

Kigali, Rwanda
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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.

Gaidashova S.V.,Institute des science Agronomiques du Rwanda ISAR | van Asten P.J.A.,International Institute Of Tropical Agriculture | Delvaux B.,Unite des science du Sol | De Waele D.,Catholic University of Leuven
Scientia Horticulturae | Year: 2010

Soil properties vary according to the topography. They affect water uptake and root exploration in the soil. Consequently, they may also influence the spread of plant-parasitic nematodes. This study reports on the effect of toposequence-related variations in soil on banana yields, foliar nutrient status, and nematode impact. Twenty banana plots were visited within 6 hills/valleys at each of the three toposequence positions: valley bottom, mid-slope and crest. Important variability in plant growth, nutrition and soil properties was observed within the toposequence. Significantly better plant growth (height and girth) was observed in the valley bottoms, where banana bunch weight was 1.7-3.4 kg higher (although not significant) than at upper toposequence positions. Best plant growth was observed in valley bottoms in contrast to the highest N and K foliar deficiencies in this position. Plants in the valley bottoms had higher foliar Ca and Mg, and K compared to those in the crest. Plants in the mid-slope had greater percentage of dead roots (19.1%), compared to the plants in the valley bottoms (12.3%) and the crest (14.2%). Soils in the valley bottoms were deeper, sandier, with lower organic matter, lower N, and K compared to the soils at higher toposequence. Nematodes likely play a key role in banana root damage, however, their effect appear to be in relation to various soil factors at each position. The abundance of Pratylenchus goodeyi had generally limited impact on banana yields in fields having less than 5% slope (crest and valley bottom) where soil conditions were more optimal for root growth. However, in the presence of increased run-off on steeper middle slopes, root death was increased even under moderate pressure from P. goodeyi. © 2010 Elsevier B.V. All rights reserved.

Gaidashova S.V.,Institute des science Agronomiques du Rwanda ISAR | Gaidashova S.V.,Catholic University of Leuven | Van Asten P.J.A.,International Institute Of Tropical Agriculture | Dochez C.,International Institute Of Tropical Agriculture | And 2 more authors.
Nematology | Year: 2010

The effect of nematode root injuries on banana crop yield is very poorly known in higher parts of the East African highlands. This study assessed the impact of the root-lesion nematode, Pratylenchus goodeyi, on growth and yield of three banana cultivars (Musa spp. AAA-EA) in a field experiment involving nematicide and mulch applications at conditions of high altitude (about 1500 m). Plant growth, yield, root damage and nematode population densities were observed over three production cycles. Low to medium levels (≤50%) of root necrosis were associated with improved plant growth, whilst higher root necrosis (>50%) had no effect on plant growth. No significant reduction in bunch weight was associated with high root necrosis in any cycle and any of the three cultivars. Mulch significantly reduced root necrosis and P. goodeyi population densities. Bunch weight significantly increased in all mulched plots irrespective of root necrosis intensity. These results agree with those of earlier surveys in Rwanda that suggested little impact of P. goodeyi on banana yields. However, they challenge general perceptions and previous findings on the negative impact of root lesion nematodes on banana crop performance. © 2010 BRILL.

Manzi M.,Institute des science Agronomiques du Rwanda ISAR | Rutagwenda T.,British Petroleum | Kanuya N.,Sokoine University of Agriculture | Chatikobo P.,Polytechnic University of Mozambique
Journal of Animal and Veterinary Advances | Year: 2011

Phenotypic characterization is a simple, non-invasive and inexpensive technology that can be utilized in mapping out an inventory of characters peculiar to a group of animals. A random sample of 487 non-descript village goats in Bugesera and Nyagatare districts were characterized according to their phenotypic characteristics. Three age categories (Based on dentition) were examined: milk, young and adults. Parameter assessed included face, back and rump profiles, presence of beards and toggles, horn, tail and ear lengths, coat color and pattern, presence of horns, live weight, heart girth, wither height, body and back lengths. Overall, 77.2% of goats sampled had a flat face while 22.8% had concave faces. About >98.4% had flat backs with 1.6% having a hollow back. All the goats in the study had a sloping rump. Only 6% had beards. About 13.5% had toggles averaging 3.4cm in length. Average horn length varied from 4.3 (±0.2) in the milk category to 8.0 (±0.1) in the mature goats. Horn diameter varied from 3.3 (±0.1) cm in the kids to 8.6 (±0.2) in adults, respectively. The mean tail length ranged from 9.6 (±0.1)42.0 (±0.1) for the same age categories. Average mean ear length ranged from 10.3 (±0.1)-l 1.5 (±0.09) (milk-adults). There was no significant difference (p>0.05) from one dentition category to another. The predominant coat color was the uniform multi-colored coat pattern. The mean live weight (kg) recorded were 13.1 (±3.3) (kids), 25.5 (±0.7) (young) and 33.3 (±0.5) (mature goats). Mean heart girth (cm) recorded was 54.4 (±0.5) (milk), 67.0 (±0.5) (young) and 74.0 (±0.4) (mature goats). The results show that goats in the study are predominantly not the East African Small type but rather are an improvement from the typical small East African goats. Implications of the present findings on goat breeding and productivity in Rwanda are discussed. © Medwell Journals, 2011.

Mutimura M.,Institute des science Agronomiques du Rwanda ISAR | Everson T.M.,University of KwaZulu - Natal
African Journal of Agricultural Research | Year: 2011

Livestock rearing in Rwanda, including the Bugesera and Nyamagabe districts is practised under stalling. This livestock farming is due to high human population resulting to land shortage where land is devoted more to cropping than to livestock production. In the Nyamagabe district, animal feed is constrained by low rainfall whereas in the Nyamagabe is constrained by the acidic soil with aluminium toxicity. The objective of this study was to determine feed resources and the availability of each feed resource that was used by farmers in the dry and wet seasons. Focus group discussions of 20 farmer representatives from each district were concerned. In each district, 20 farmers identified criteria to rank the identified feed resources. Individual farmers gave score to each identified feed resource according to farmers' criteria and the scores were considered as quantities measured. In the low rainfall district (Bugesera), four exotic, three indigenous fodder species and six crop residues were identified with preference scores ranging from zero to ten. Pennisetum purpureum (Napier grass) was given the highest scores ranged between six and eight because of its availability all year round. The native grass received a median score of five for its availability year round. In acidic soil area (Nyamagabe district), five exotic fodder species, five indigenous fodder species and 11 crop residues were identified. Napier grass and Commelina benghalensis were scored high with a median score of eight. The preference ranking confirmed that overall Napier grass was the major fodder crop used throughout the two districts followed by some indigenous species and crop residues. The availability of quality and quantity of feeds has shown a shortage of livestock feed resources in both districts and it requires a suitable forage species adapted to these areas of low rainfall and acidic soils. © 2011 Academic Journals.

Mukuralinda A.,Institute des science Agronomiques du Rwanda ISAR | Tenywa J.S.,Makerere University | Verchot L.,International Center for Research in Agroforestry | Obua J.,Makerere University | And 2 more authors.
Agroforestry Systems | Year: 2010

Green manure of multipurpose trees is known to be a good source of nutrients to crop. However, most agroforestry species do not have adequate phosphorus (P) in their leaves. Supplementing green manure with moderate dose of P is a beneficial strategy to improve food security in Rwanda. This study examines the effects of Calliandra calothyrsus Meissner, Tithonia diversifolia Hensley A. Gray and Tephrosia vogelii Hook. f. green manure applied independently or in combination with triple super phosphate (TSP) and lime on maize yield and P uptake in the Oxic Tropudalf of Rubona, Rwanda. The treatments were the control, lime at 2.5 t ha-1, TSP at 25 and 50 kg P ha-1, leaf of C. calothyrsus, T. diversifolia, and T. vogelii each at 25 and 50 kg P ha-1, respectively. Leaf shrubs biomass, TSP and lime were applied for four consecutive seasons (2001-2004). The results showed that the combination of green manure with TSP at a rate of 50 kg P ha-1 significantly increased maize yield from 24 to 508% when compared to the control and T. divesifolia combined with TSP was leading (508%). Equally, the same treatments as indicated above showed higher P uptake (15.6-18.6 kg P ha-1) than the control (5 kg P ha-1) and 65% of maize yields variation was explained by total P uptake. The plant residues quality such as C:N ratio, total plant N, and P significantly influenced the variability of maize grain yields. © 2010 Springer Science+Business Media B.V.

Butare L.,Centro Internacional Of Agricultura Tropical Ciat | Butare L.,University of Liège | Butare L.,Institute des science Agronomiques du Rwanda ISAR | Rao I.,Centro Internacional Of Agricultura Tropical Ciat | And 5 more authors.
Euphytica | Year: 2012

Aluminium (Al) toxicity limits common bean productivity in acid soil regions of the tropics. To improve Al resistance of common bean, Al-sensitive Phaseolus vulgaris (SER16) was crossed to Al-resistant P. coccineus (G35346-3Q) to create 94 F 5:6 recombinant inbred lines (RILs) of the pedigree SER16 × (SER16 × G35346-3Q). RILs were characterized for resistance to Al in a hydroponic system with 0 and 20 μ M Al in solution, and for shoot and root growth response to Al-toxic infertile acid soil in 75 cm long soil cylinder system using an oxisol of low Al- (12.5%; pH 4.6; fertilized) and high Al-saturation (77%; pH 4.1; unfertilized). G35346-3Q increased its taproot elongation rate by 3.5% between 24 and 48 h under 20 μM Al in solution, while the best RIL, Andean genotype ICA Quimbaya, and sensitive genotype VAX1 expressed reductions of 2.6, 12.5, and 69.5%, respectively. In the acid soil treatment the correlation between leaf area and total root length was highly significant under high Al saturation (r = 0.70 ***). Genotypes that were Al resistant in the hydroponic system were not necessarily tolerant to Al-toxic acid soil conditions based on shoot and root growth responses. Phenotypic evaluation using both systems allows the identification of genotypes with Al resistance combined with acid soil adaptation. Two genotypes (ALB88 and ALB91) emerged as lines with multiple traits. Results suggest that inheritance of Al resistance and acid soil tolerance in G35346-3Q is complex. Results from this work will be useful for identification of molecular markers for Al resistance in Phaseolus species and to improve acid soil adaptation in common bean. © 2011 Springer Science+Business Media B.V.

Lyumugabe F.,University of Liège | Lyumugabe F.,National University of Rwanda | Gros J.,Catholic University of Louvain | Nzungize J.,Institute des science Agronomiques du Rwanda ISAR | And 2 more authors.
Biotechnology, Agronomy and Society and Environment | Year: 2012

Traditional sorghum beers are produced in several countries of Africa, but variations in the manufacturing process may occur depending on the geographic localization. These beers are very rich in calories, B-group vitamins including thiamine, folic acid, riboflavin and nicotinic acid, and essential amino acids such as lysine. However, the traditional sorghum beer is less attractive than Western beers because of its poorer hygienic quality, organoleptic variations and shorter shelf life. Research into the microbiological and biochemical characteristics of traditional sorghum beers as well as their technologies have been performed and documented in several African countries. This review aims to summarize the production processes and compositional characteristics of African traditional sorghum beers (ikigage, merissa, doro, dolo, pito, amgba and tchoukoutou). It also highlights the major differences between these traditional beers and barley malt beer, consumed worldwide, and suggests adaptations that could be made to improve the production process of traditional sorghum beer.

Butare L.,Centro Internacional Of Agricultura Tropical Ciat | Butare L.,University of Liège | Butare L.,Institute des science Agronomiques du Rwanda ISAR | Rao I.,Centro Internacional Of Agricultura Tropical Ciat | And 5 more authors.
Euphytica | Year: 2011

Bean species and genotypes show wide phenotypic variability in relation to aluminium (Al) resistance and progressive soil drying. The objective of this study was to identify and characterize sources of resistance to Al toxicity and progressive soil drying among six genotypes of common bean (Phaseolus vulgaris), four of runner bean (P. coccineus), and one of tepary bean (P. acutifolius), using hydroponic and soil cylinder screening methods. One experiment on hydroponic screening of Al resistance was carried out using a basal nutrient solution with and without 20 μM Al. Two experiments were carried out using two oxisols in 80 cm long soil cylinders with high Al (HAl) and low Al (LAl) saturation treatments. The three experiments showed an average of 36.9-53.5% inhibition of root growth with HAl compared with LAl treatments. Differences in root development and distribution were observed among genotypes and species. Two accessions of P. coccineus (G35346-c-5Q) and one Andean common bean genotype (ICA Quimbaya) were outstanding in root and shoot growth in the HAl treatments. P. coccineus accession (G35346-3Q) was outstanding under combined stress of Al-toxic acid soil and progressive soil drying. Accessions of P. coccineus may represent unique sources of Al resistance for the improvement of common bean through interspecific crosses. © 2011 Springer Science+Business Media B.V.

Blair M.W.,International Center For Tropical Agriculture Centro Internacional Of Agricultura Tropical Ciat | Gonzalez L.F.,International Center For Tropical Agriculture Centro Internacional Of Agricultura Tropical Ciat | Kimani P.M.,University of Nairobi | Butare L.,Institute des science Agronomiques du Rwanda ISAR
Theoretical and Applied Genetics | Year: 2010

The Great Lakes region of Central Africa is a major producer of common beans in Africa. The region is known for high population density and small average farm size. The common bean represents the most important legume crop of the region, grown on over a third of the cultivated land area, and the per capita consumption is among the highest in the world for the food crop. The objective of this study was to evaluate the genetic diversity in a collection of 365 genotypes from the Great Lakes region of Central Africa, including a large group of landraces from Rwanda as well as varieties from primary centers of diversity and from neighboring countries of Central Africa, such as the Democratic Republic of Congo and Uganda, using 30 fluorescently labeled microsatellite markers and automated allele detection. In addition, the landraces were evaluated for their seed iron and zinc concentration to determine if genetic diversity influenced nutritional quality. Principal coordinate and neighbor-joining analyses allowed the separation of the landraces into 132 Andean and 195 Mesoamerican (or Middle American) genotypes with 32 landraces and 6 varieties intermediate between the gene pools and representing inter-gene pool introgression in terms of seed characteristics and alleles. Genetic diversity and the number of alleles were high for the collection, reflecting the preference for a wide range of seed types in the region and no strong commercial class preference, although red, red mottled and brown seeded beans were common. Observed heterozygosity was also high and may be explained by the common practice of maintaining seed and plant mixtures, a coping strategy practiced by Central African farmers to reduce the effects of abiotic and biotic stresses. Finally, nutritional quality differed between the gene pools with respect to seed iron and zinc concentration, while genotypes from the intermediate group were notably high in both minerals. In conclusion, this study has shown that Central African varieties of common bean are a source of wide genetic diversity with variable nutritional quality that can be used in crop improvement programs for the region. © 2010 The Author(s).

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