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21.
Combating viral mosaic disease of cassava in the Lake Zone of Tanzania by intercropping with legumes
Cassava (Manihot esculenta Crantz) production is constrained by many factors, including the viral cassava mosaic disease (CMD). This study was conducted to explore the potential of intercropping cassava with legumes to reduce CMD effects on cassava production. Local (Lyongo Kwimba) and improved (Suma) cassava varieties were intercropped with three types of grain legumes (groundnut, Arachis hypogea L. var. Upendo; cowpea, Vigna unguiculata (L.) Walp. var. Vuli; and green gram, Vigna radiata (L.) R. Wilczek var. Imara). Monocrops of cassava with and without NPK fertilizer were included as controls. The experiment was established using a randomized complete block design with four replications in a split-plot arrangement for three seasons. Cassava varieties intercropped with cowpeas, green gram, and groundnuts and cassava monocrops with and without NPK fertilizer constituted the main plot and sub-plots, respectively. Whitefly population counts and CMD severity and incidence were measured at regular intervals. Cropping system had a significant effect (P < 0.05) on whitefly populations and CMD severity. Small whitefly populations (0–7.5 individuals per leaf) and low CMD severity (1–2.4 on a 5-point scale) were recorded in improved and local cassava varieties intercropped with green gram. The local cassava variety intercropped with green gram showed low CMD incidences (0%–40%) in all seasons. Generally, growing cassava with green gram proved effective in reducing whitefly populations and CMD incidence and severity. Intercropping cassava with grain legumes may improve cassava production and food security in CMD-prone areas of the Lake Zone of Tanzania and areas with similar environments. 相似文献
22.
Kivaria FM 《Tropical animal health and production》2006,38(4):291-299
Tick-borne diseases, namely, anaplasmosis, babesiosis, cowdriosis and theileriosis, constrain cattle production and improvement
in Tanzania, leading to considerable economic losses. A simple spreadsheet model was used to estimate the economic losses
resulting from production losses, treatment and control costs associated with tick-borne diseases (TBD) in Tanzania. Model
parameters included the national cattle population, reported TBD morbidity, fatality risk, and chemotherapy and control measures
used. The total annual national loss due TBD was estimated to be 364 million USD, including an estimated mortality of 1.3
million cattle. Theileriosis accounted for 68% of the total loss, while anaplasmosis and babesiosis each accounted for 13%
and cowdriosis accounted for 6% of the total loss. Costs associated with mortality, chemotherapy and acaricide application
accounted for 49%, 21% and 14% of the total estimated annual TBD losses, respectively, infection and treatment method milk
loss and weight loss accounted for 1%, 6% and 9% of the total annual loss, respectively. Despite the inadequacies of the data
used, the results give evidence that tick-borne diseases inflict substantial economic losses on cattle production and resource
use in Tanzania. 相似文献
23.
E.F.NZUNDA 《中国林学(英文版)》2012,14(3):210-215
It is important to revisit our plans and compare what was ideally targeted against what was actually achieved in implementation.In comparing the achievements with targets,strengths or weaknesses of established strategies can be accepted or corrections implemented since a plan also outlines some strategies for achieving the targets set.In this study,achievements in production and export of industrial forest products,i.e.,sawn wood,plywood,chipboard and fibreboard,paper and paperboard and industrial round wood,are compared against targeted figures for 1996 for Tanzania.Discrepancies were obtained by subtracting targeted from achieved values and expressed both as absolute and relative differences in terms of the targeted values,with a negative sign for production where achievements were less than targets and a positive sign when achievements were higher than targets.Values achieved ranged from 4%-100% of the targeted values,depending on the product,and were only higher than the targeted value for industrial round wood.Possible causes of the discrepancies are inefficiency of parastatal companies,low private investment,sub-maximal industrial operation and plant inefficiencies.Discrepancies could also result from unrealistic data used in planning due to difficulty in data availability and poor intra-and inter-sectoral coordination.The implications of these discrepancies are low contributions of the wood-based industry to the national economy,increased import substitution of wood-based products,increased socio-economic and environmental degradation and decreased integrity in planning and policy making. 相似文献
24.
The objective of this study was to describe the prevalence of brucellosis in various occupations in Tanga, Tanzania. During the year 2004, serum samples were collected from volunteers in various occupations and screened for brucella antibodies using Rose Bengal Plate Agglutination Test. Information on occupation, kind of work and contacts with livestock was collected and age and sex were recorded. The overall sero prevalence of antibodies to Brucella abortus was 5.52%. One variable in a multivariate regression model was significantly associated with seropositivity to B. abortus: abattoir workers. The prevalence of antibody was significantly higher (P < 0.05) among personnel employed in high-risk jobs such as cutting animal throats and cleaning slaughtered animals parts. None of the other factors investigated was associated with seropositivity to B. abortus. This study documents the serological evidence of B. abortus infection for the first time in abattoir workers in Tanzania. 相似文献
25.
Baelmans R Parmentier HK Nieuwland MG Dorny P Demey F Berkvens D 《Tropical animal health and production》2005,37(3):173-186
A total of 376 chickens from different ecotypes were immunized with the non-pathogenic multi-determinant antigen sheep red blood cells (SRBC). The ecotypes included indigenous chickens from various locations in Tanzania (n=102), India (n=86) and Bolivia (n=89). In addition, eight German Dahlem Red (GDR) chicken lines with different major genes (dwarf, naked neck and frizzled) of tropical interest were also immunized with SRBC. Immune competence of the breeds was assessed by measuring complement haemolytic activity, both from the classical calcium-dependent complement pathway (CPW) and alternative calcium-independent complement pathway (APW), alongside IgTotal, IgG and IgM antibody responses to SRBC at 7 days post immunization. Large variations in complement activity and antibody responses to SRBC were observed within and between the indigenous breeds. Many indigenous chickens, especially from Bolivia, showed decreased complement activity (APW) following immunization with SRBC. Breeds from India showed the highest CPW activity and humoral (especially IgM) responses to SRBC, suggesting high immune competence. In contrast, Bolivian chickens were characterized by low CPW activity, low APW activity and low antibody levels to SRBC suggesting an overall low immune competence. In the GDR chickens, characterized by high CPW activity and high IgG antibody responses to SRBC, the major genes for naked neck, frizzling and dwarfism had no significant effect on the antibody responses and complement activity to SRBC. 相似文献
26.
Brita?Dahl?JensenEmail author Said?M.?S.?Massomo Ignas?S.?Swai John ?Hockenhull Sven?Bode?Andersen 《European journal of plant pathology / European Foundation for Plant Pathology》2005,113(3):297-308
Black rot, caused by Xanthomonas campestris pv. campestris, (Xcc), is one of the most serious diseases of crucifers world-wide. Forty-nine genotypes were evaluated for resistance under field
conditions in Tanzania after artificial inoculation with Xcc race 1. Open pollinated white cabbage cultivars were generally susceptible, while Portuguese and pointed cabbages exhibited
partial resistance. Some F1 white cabbage cultivars were highly susceptible, whereas others exhibited a high level of partial
resistance. The most promising of the hybrid cultivars were T-689 F1, Gianty F1, No. 9690 F1, N 66 F1, and SWR-02 F1. Breeding
line Badger I-16 exhibited the highest level of resistance of all genotypes. The genotypes accounted for 72.9–75.5% of the
variation of the disease severity when assessed on the leaves, and 71.4% of the variation when assessed as internal black
rot in heads at harvest. High correlations (equal to or above 0.7) were found between disease severities assessed on leaves
three times during the growing season and also with the amount of internal black rot in heads. Leaf loss also was correlated
with disease severity. The high genetic determination of the trait and the high correlations between disease assessments indicate
that selection for resistance to black rot will be efficient when field screenings are carried out. Evaluation of genotypes
for disease severity on leaves during the growing season combined with evaluations of head resistance in the most promising
genotypes may be a simple method to select resistant cultivars. 相似文献
27.
28.
Hassan Bashiru Shelukindo Balthazar Msanya Ernest Semu Sibaway Mwango Bal Ram Singh Pantaleo Munishi 《农业科学与技术》2014,(3):224-234
Despite the fact that miombo woodland soils have significant implications in global climate change processes, few studies have been done to characterize and classify the soils of the miombo woodland ecosystem of Tanzania. The current study was carried out to map and classify soils of Kitonga Forest Reserve, which is a typical miombo woodland ecosystem, in order to generate relevant information for their use and management. A representative study area of 52 km2 was selected and mapped at a scale of 1:50,000 on the basis of relief. Ten representative soil profiles were excavated and described using standard methods. Soil samples were taken from genetic soil horizons and analyzed in the laboratory for physico-chemical characteristics using standard methods. Using field and laboratory analytical data, the soils were classified according to the FAO-World Reference Base (FAO-WRB) for Soil Resources system as Cambisols, Leptosols and Fluvisols. In the USDA-NRCS Soil Taxonomy system the soils were classified as Inceptisols and Entisols. Topographical features played an important role in soil formation. The different soil types differed in physico-chemical properties, hence exhibit differences in their potentials, constraints and need specific management strategies. Texture varied from sandy to different loams; pH from 5.1 to 5.9; organic carbon from 0.9 g/kg to 20 g/kg; and CEC from 3 cmol/(+)kg to 24 cmol/(+)kg. Sustainable management of miombo woodlands ecosystem soils requires reduced deforestation and reduced land degradation. 相似文献
29.
R. G. BAILEY 《Fisheries Management and Ecology》1996,3(3):251-260
Abstract Nyumba ya Mungu Reservoir in northern Tanzania has a maximum surface area of 180 km2, an average depth of 6 m, and contains moderately saline, fertile water. The postimpoundment decade, 1965–74, was characterised by a spectacular rise and fall of a tilapiabased fishery. Since then a gill-net fishery catching large numbers of large, periphyton-grazing tilapias has given way to a mainly beach-seine fishery producing large numbers of small, phytoplankton-feeding Oreochromis esculentus (Graham). Yields remain higher than preimpoundment predictions but the size at maturity of all tilapia species has fallen and few larger than 15 cm TL are caught. These changes, and others in the fish community trophic structure, are chiefly explained by changes in the littoral environment and fishing pressures. Nyumba ya Mungu provides a case history of developments in the tilapia fishery of a man-made river lake conducted on an essentially laissez-faire basis. 相似文献
30.
Screening of subclinical mastitis under field conditions is done using the California mastitis test (CMT). CMT score of ≥1 corresponding to ≥500,000 somatic cells ml−1 is commonly used as threshold of subclinical mastitis in temperate countries. However, given the innately high physiological level of somatic cells in low yielding dairy cows, this threshold may not apply to low yielding dairy cows. The current study was undertaken to investigate the clinical utility of CMT for screening of Staphylococcus aureus subclinical mastitis in low yielding smallholder dairy cows in Tanzania. A total of 1151 of quarter-milk samples were CMT tested, of these 914-originated from cows with a lactation period of 14–305 days. All samples were screened for subclinical mastitis by the CMT as well as microbiological culture of single, duplicate (two consecutive) and triplicate (three consecutive) samples as a gold standard. For the duplicate and triplicate quarter-samples, cows were considered positive for S. aureus subclinical mastitis if results of microbiologic culture for S. aureus were positive for two of two, and for at least two of the first three consecutive quarter-milk samples collected from that cow, respectively. Using a CMT score of ≥1 would classify 78.6% of the 940 quarter-samples as positive. Eighty-two percent of the samples in which S. aureus was isolated had CMT scores ≥2; this would classify 51.6% of the 940 quarter-samples as positive. For the single sample, this cut-off had sensitivity, specificity and likelihood ratio for S. aureus of 0.87, 0.83 and 4.24, respectively. For the duplicate quarter-milk samples this cut-off had sensitivity, specificity, and likelihood ratio of 0.94, 0.86, and 5.19. While, for the triplicate quarter-milk samples this cut-off had sensitivity, specificity and likelihood ratio of 0.97, 0.92 and 7.47, respectively. Based on these results and practical considerations, it is concluded that CMT score of ≥2 corresponding to ≥800,000 somatic cells Ml−1 is the best cut-off to correctly identify S. aureus intramammary infections in low yielding dairy cows in Tanzania. 相似文献