Showing papers by "University of Zimbabwe published in 1993"
TL;DR: In this paper, the authors investigated the effect of wood use on wood supply and the current uses of wood and found that the majority of farmers leave indigenous trees, predominantly fruit-bearing species, in cultivated lands and wooded grasslands, supporting little woody biomass.
117 citations
TL;DR: In this article, a flexible system of fertilization was devised which allowed for high yields in wet years, and reduced financial losses in dry years, based on generalized soil properties and the total nutrient uptake required for a crop to achieve its maximum yield potential in a season with average rainfall.
Abstract: Fertilizer use in the semi-arid tropics is considered risky because of the unreliable rainfall pattern. A flexible system of fertilization was devised which allowed for high yields in wet years, and reduced financial losses in dry years. Relatively immobile nutrients, such as phosphorus, potassium and sulphur, were applied at rates determined from generalized soil properties and the total nutrient uptake required for a crop to achieve its maximum yield potential in a season with average rainfall. Nitrogen was applied as a series of split applications, which were adjusted during the season according to the degree of water stress observed. This approach was tested in on-farm trials for maize production on nutrient-poor sandy soils in three regions of Zimbabwe, and resulted in larger yields and profits than current recommendations, providing an accept able level of financial return. Small further yield increases were possible, at acceptable returns, when these fertilizer practices were combined with the establishment of tied-ridges by ox-drawn implements, 30 days after planting. By careful estimation of yield potential, and appropriate adjustments to soil fertility, this system of soil management could be applied to other cropping situations and other areas with variable rainfall.Uso de fertilizantes para condiciones de precitacion variable
101 citations
TL;DR: Environmental toxicology emphasizes the difference from traditional toxicology in which pure compounds of interest are added to purified diets, or injected into the test animals, when the objective is to study the fate and effects of trace elements in the environment.
99 citations
TL;DR: In this paper, structural features are best explained by a combination of pluton diapirism and ballooning plutonism, including foliation and stretching lineation trajectories, the variation in strain type and strain intensity, fold types, sense of shear at the batholith-greenstone interface, metamorphic zoning and timing of porphyroblast growth.
85 citations
TL;DR: It is concluded that the K+ ion content of Portulaca oleracea is at least partly responsible for the relaxant effect observed on the isolated rat diaphragm.
81 citations
TL;DR: In this article, the authors investigated the relationship between vane shear strength and moisture content for root-free and root-permeated sandy clay loam and clay soils with a view to determining the effect of root density on the relationship.
79 citations
TL;DR: The gills of six species of cichlid present in Lake Kariba (Zimbabwe) revealed the presence of twelve species of CichLidogyrus, five being new species, one of which, C. mortimeri, is elevated to specific status.
Abstract: The gills of six species of cichlid present in Lake Kariba (Zimbabwe) revealed the presence of twelve species of Cichlidogyrus, five being new species. The parasites were as follows: C. halli (Price & Kirk, 1967) in Oreochromis mortimeri (main host) and Serranochromis macrocephalus (occasional host); C. tilapiae Paperna, 1960 and C. longicornis Paperna & Thurston, 1969 in O. mortimeri only; C. sclerosus Paperna & Thurston, 1969 in O. mortimeri (main host) and in S. macrocephalus (occasional host); C. haplochromii Paperna & Thurston, 1969 in Pharyngochromis darlingi only; C. tiberianus Paperna, 1960 in Tilapia rendalli only; C. dossoui n. sp. in T. rendalli (type-host) and in O. mortimeri and S. macrocephalus (occasional hosts); C. karibae n. sp. in S. codringtonii (type-host) and in O. mortimeri (occasional host); C. zambezensis n. sp. in S. macrocephalus (type-host) and in O. mortimeri (occasional host); C. quaestio n. sp. in T. rendalli (type-host) and in S. codringtonii and S. macrocephalus (occasional hosts); C. philander n. sp. in Pseudocrenilabrus philander. C. longicornis gravivaginus Paperna & Thurston, 1969, found in O. mortimeri, is elevated to specific status.
74 citations
TL;DR: In this article, the authors show that the two cratons have fundamentally different geological histories and that the Zimbabwe Craton was unlikely to have behaved as a stable ‘cratonic’ block at the time of the Limpopo Belt collision.
Abstract: The Limpopo Belt is a zone of thickened Archaean crust whose origin is currently explained by a late Archaean continent-continent collision between the Kaapvaal and Zimbabwe cratons. This review shows that the two cratons have fundamentally different geological histories and that the Zimbabwe Craton was unlikely to have behaved as a stable ‘cratonic’ block at the time of the Limpopo Belt collision. The geological histories of the Zimbabwe Craton, the North Marginal, Central and South Marginal zones of the Limpopo Belt and the Kaapvaal Craton are shown to be sufficiently different from one another to warrant their consideration as discrete terranes. The boundaries between the five units outlined above are all major shear zones, further supporting a terrane model for the Limpopo Belt. The five units were all intruded by late- to syn-tectonic granites c.2.6 Ga, constraining the accretion event to c. 2.6 Ga.
73 citations
TL;DR: It is suggested that mothers' pragmatic attitudes, interacting with certain social, cultural, and economic variables, are important factors influencing their child feeding decisions, especially resisting the use of commercial infant formula, at least in this rural area, and promoting prolonged breastfeeding.
65 citations
TL;DR: The findings are in agreement with the 0-2% prevalence of poor metabolizers (PMs) in the black populations previously phenotyped and indicate important interethnic differences in the CYP2D locus between Caucasian, Asian and different black populations.
Abstract: The objective of this study was to determine the CYP2D6 genotype of a black Zimbabwean population. Genotyping was carried out using Eco RI and Xba I RFLP, and allele-specific PCR amplification. Of 114 Zimbabwean samples analysed, no individual homozygous for any of the defect allelic forms CYP2D6A, CYP2D6B or CYP2D6D or combinations thereof was found. The allele frequencies of the three defect genes were 0, 1.8 and 3.9%, respectively. No subject carrying the Xba I 44 kb haplotype, indicative for poor metabolizers among Caucasians, was identified, whereas five individuals being heterozygous with a 29/42 kb haplotype were seen. Three out of the four CYP2D6B alleles found were associated with the 29/42 kb haplotype. Our findings are in agreement with the 0-2% prevalence of poor metabolizers (PMs) in the black populations previously phenotyped. The very low frequency of the CYP2D6B allele in the Zimbabwean population is different from very recent data from black Americans (allele frequency = 8.5%) and might indicate the Caucasian ancestry of this allele. Taken together, our data indicate important interethnic differences in the CYP2D locus between Caucasian, Asian and different black populations.
64 citations
TL;DR: The authors suggests that settlement programs are too often designed with the assumption that all settlers will succeed, which has led to centralized administration and rigid designs, rather than decentralized approaches, flexibility in implementation, support for spontaneous settlement, and reliance on settlers' own investment capacity.
TL;DR: The Ngezi Group in the Belingwe greenstone belt has been interpreted as continental basalts extruded onto, or oceanic crust obducted onto, a succession of stable-shelf sedimentary rocks that nonconformably overlie continental basement.
Abstract: Volcanic rocks of the Ngezi Group in the Belingwe greenstone belt have been interpreted as continental basalts extruded onto, or oceanic crust obducted onto, a succession of stable-shelf sedimentary rocks that nonconformably overlie continental basement. The volcanic succession locally contains quartzose sandstones, and the stratigraphy is unlike ocean crust. Primary volcanic and sedimentary structures indicate a shallow-subaqueous to subaerial origin. All structural features are compatible with later refolding of an autochthonous successon; there is no structural manifestation of obduction. These criteria refute an oceanic setting for the volcanic rocks; rather, they are consistent with an ensialic origin for the Ngezi Group.
TL;DR: It was found that all situations associated with diminished, or absent social support, that is, being single, divorced, widowed, one of several wives, cohabiting, or self-supporting carried an increased risk for maternal mortality, especially in the rural area.
Journal Article•
TL;DR: Results suggest that cattle are important reservoirs of C. burnetii in Zimbabwe, and serological evidence of Q fever infection was found in 39% of cattle, but only 15% of dogs and 10% of goats.
Abstract: Sera from 494 hwnans, 180 cattle, 180 goats and 27 dogs, collected from different regions of Zimbabwe, were examined by indirect fluores cence for antibodies reactive with phase 11 Coxiella burnetii antigen. Overall, 37% of hwnans were reactive at a titre of 1140 or greater, and there was no evidence of age- or sex-related differences in seroprevalence. A review of clinical and epi demiological features of Q fever is presented in order to alert health workers to this infection, which apparently occurs frequently in Zimbabwe even though clinical cases have not been reported. In animals, serological evidence of Q fever infec tion was found in 39% of cattle, but only 15% of dogs and 10% of goats. These results suggest that cattle are important reservoirs of C. burnetii in Zimbabwe. S Air Med J 1993; 83: 21 ·25.
TL;DR: There was a significantly higher prevalence of non-regenerative anaemia in dogs with antibodies to E canis than in Dogs with both infections and the prevalence of thrombocytopenia was significantly higher indogs with babesiosis than in dogs in the study.
Abstract: Of 105 dogs examined at a veterinary hospital in Harare, Zimbabwe, 52 per cent had antibodies reactive with Ehrlichia canis in indirect fluorescent antibody tests, 26 per cent had Babesia canis parasites in peripheral blood smears and 17 per cent had both infections. None of the dogs with serological evidence of ehrlichiosis had typical E canis morulae detectable in blood smears. The infections were regarded as incidental findings not readily related to the reasons for examination in 46 per cent of the dogs with antibodies to E canis and 17 per cent of the dogs with both infections. The most common laboratory abnormalities were anaemia and thrombocytopenia and the prevalence and severity of these in concurrent infections were intermediate to those found in individual infections. There were no pathognomonic clinical signs or laboratory abnormalities which could be used to distinguish between individual and concurrent infections. However, there was a significantly higher prevalence of non-regenerative anaemia in dogs with antibodies to E canis than in dogs with both infections. The prevalence of thrombocytopenia was significantly higher in dogs with babesiosis than in dogs with antibodies to E canis and the prevalence of hyperglobulinaemia was significantly higher in dogs with both infections than in dogs with antibodies to E canis.
TL;DR: A questionnaire survey of small-scale farmers was conducted to elucidate the practices associated with acquisition and use of miombo litter, finding that cattle ownership is related to quantities of litter collected and the destination of the collected litter.
Abstract: A questionnaire survey of fifty-two small-scale farmers was conducted to elucidate the practices associated with acquisition and use of miombo litter. On average, a household cropped 3.7 ha of land and owned ten head of cattle. Farmers collected, on average, 0.5 t of litter per household per annum with larger amounts collected by those with more cropland and more cattle. Cattle ownership is related to quantities of litter collected and the destination of the collected litter, most of the litter being cured in cattle pens. Farmers with less area of cropland applied greater quantities of litter per hectare of cropland than did farmers with more cropland. On average, five tons per hectare per season of the manure-litter mixture is applied to crop fields with litter contributing, on average, 0.12 t/ha to the mixture. Some crops, particularly maize and fingermillet, are more likely to receive litter than other crops.
Journal Article•
TL;DR: The essential oil from the fresh leaves of Schinus molle isolated by hydrodistillation was tested for antibacterial activity and for antifungal activity using the hole plate diffusion method and the mycelium or single cell growth inhibition method.
Abstract: The essential oil from the fresh leaves of Schinus molle isolated by hydrodistillation was tested for antibacterial activity using the hole plate diffusion method and for antifungal activity using the mycelium or single cell growth inhibition method. Results obtained showed that the volatile oil exhibited significant activity against the following bacterial species: Klebsiella pneumoniae, Alcaligenes faecalis, Pseudomonas aeruginosa, Leuconostoc cremoris, Enterobacter aerogenes, Proteus vulgaris, Clostridium sporogenes, Acinetobacter calcoacetica, Escherichia coli, Beneckea natriegens, Citrobacter freundii, Serratia marcescens, Bacillus subtilis and Brochothrix thermosphacata. The fungal species Aspergillus ochraceus, Aspergillus parasiticus, Fusarium culmorum and Alternaria alternata exhibited significant sensitivity to the volatile oil.
TL;DR: During the early stages of the spring flush, carbon asimilation rates of the flushing leaves were inversely related to leaf anthocyanin concentrations, and in pre-rain green leaves, photosynthesis was limited by other non-stomatal factors.
Abstract: Changes in net carbon assimilation and water status were studied during leaf development in the deciduous, tropical species Brachystegia spiciformis Benth. In this upland savanna African tree, bud-burst and leaf development occur approximately two months before the rainy season. The newly formed leaves synthesize anthocyanin until the fully expanded leaves of the whole canopy are red. This foliage is referred to as "spring flush" foliage. Subsequently, the anthocyanins are metabolized and the pre-rain leaves become green. Carbon dioxide assimilation exhibited a bimodal diurnal pattern and was similar for pre-rain green leaves and fully expanded flushing leaves, although pre-rain green leaves showed a net uptake of carbon throughout the daylight period, whereas flushing leaves exhibited only brief periods of net photosynthesis in the morning and early afternoon. Measurements of leaf water potential and relative water content showed a diurnal pattern with considerable variation throughout the day. Leaf water potential and relative water content values decreased soon after sunrise reaching a minimum at a time corresponding to the afternoon peak in CO(2) assimilation. Stomatal conductance was closely related to transpiration rate in both flushing and pre-rain green leaves, although flushing leaves had lower stomatal conductances than pre-rain green leaves. Pre-rain green leaves exhibited a compensation irradiance of approximately 180 micro mol m(-2) s(-1), whereas flushing leaves had positive net photosynthesis only at PPFDs greater than 300 micro mol m(-2) s(-1). Rate of photosynthesis (expressed per leaf area or chlorophyll unit) increased as anthocyanin concentration decreased, although the photosynthetic rate continued to increase long after the leaf anthocyanins had been degraded to low, visually undetectable amounts. Post-rain green leaves had chlorophyll concentrations, transpiration rates and stomatal conductances similar to those of pre-rain green leaves; however, photosynthetic rates in post-rain leaves were more than three times higher. Thus, during the early stages of the spring flush, carbon asimilation rates of the flushing leaves were inversely related to leaf anthocyanin concentrations. In pre-rain green leaves, photosynthesis was limited by other non-stomatal factors.
TL;DR: In this article, the authors show that even if the producer price needed for self-sufficiency is below import parity, food selfsufficiency may inflate food costs and exacerbate rural and urban food insecurity compared to a self-rellance policy involving imports.
TL;DR: In this paper, the authors construct indices of total factor productivity (TFP) for both the commercial and communal sectors, which show that TFP growth since independence has been impressive.
Abstract: About three quarters of the population of Zimbabwe is mainly dependent on agriculture, including wage remittances; the sector accounts for over I 2 % of GDP, about 24% of formal employment and is the main source of foreign currency, bringing in about 40% of the total. The sector is dualistic, with commerical farms producing nearly 70?% of output and contributing about 8o % of sales (95 % for tobacco, the main export); the rest is accounted for by semi-subsistence agriculture in the communal lands. Since independence, resources have been concentrated on improving the performance of agriculture in the communal areas, where output and sales have increased rapidly, largely due to the widespread adoption of hybrid maize. The commercial area has shrunk, by about I 5 %, as a result of land purchases for resettlement, which are intended to make the distribution of land more equitable. The process is likely to accelerate, since the Land Acquisition Bill, passed in February I 992, makes compulsory government purchases for resettlement easier. The government's dilemma is that the efficiency of the commercial farms is important to future development, since Zimbabwe can ill afford to lose scarce foreign exchange. This paper constructs indices of total factor productivity (TFP) for both the commercial and communal sectors, which show that TFP growth since independence has been impressive. The TFP results are supported by econometric estimation of a production function for the commercial farms and by estimation of the rate of return to agricultural research, which appears to explain most of the growth of productivity in the commercial sector.
Journal Article•
TL;DR: The authors examines the meaning of the concept of civil society with reference to Zimbabwe and argues that civil society in Zimbabwe, especially in the Black community, is in a state of chronic underdevelopment as a result of historical factors related to pre- and post-Independence politics.
Abstract: This article critically examines the meaning of the concept of civil society with reference to Zimbabwe. This is done against the background of renewed scholarly interest in the impact of state-society relations on the process of democratization in the Third World. Looking at civil society and the state as intertwining parts of the same social reality, the article argues that civil society in Zimbabwe, especially in the Black community, is in a state of chronic underdevelopment as a result of historical factors related to pre- and post-Independence politics. These factors include the value premises of colonial institutions, African tradition and the liberation war, all of which have had decisive influences in shaping and constraining the development of civil society in Zimbabwe.
TL;DR: In this article, the authors show that the elimination of policy constraints that block small-scale millers' access to grain would reduce overall marketing costs, thereby allowing higher producer prices, lower consumer prices and/or lower government subsidies.
TL;DR: Malnutrition, severe ALRI, age of 1 to 6 months, concurrent diarrhoea, duration of cough > or = 14 days and previous history of admission for ALRI were significant risk factors for mortality in ALRI.
Abstract: A descriptive study was undertaken to document clinical and socio-demographic features and also to identify risk factors for mortality in children hospitalized with acute lower respiratory tract infection (ALRI). A total of 704 children aged from 1 month to 5 years admitted to Harare Central Hospital were studied. The peak age group was between 1 and 6 months. Seventy per cent of the children were found to have normal nutrition and 12% severe malnutrition. Seventy-eight per cent had severe and the remainder moderate ALRI (WHO classification). Clinical HIV infection was diagnosed in 219 (31%) children. One hundred and four children died, an overall case fatality rate (CFR) of 15%. In the clinically HIV-infected children, a CFR of 28% occurred, which constituted 60% of the overall ALRI mortality. A much lower CFR of 9% was found in the clinically non-HIV-infected children. Malnutrition, severe ALRI, age of 1 to 6 months, concurrent diarrhoea, duration of cough > or = 14 days and previous history of admission for ALRI were significant risk factors for mortality in ALRI. Low birthweight was not found to be a risk factor in this study. The impact of HIV infection on mortality in children with ALRI is of major concern in Zimbabwe and should be an important component of the national ALRI programme.
TL;DR: The results indicate that the attenuation of central gamma-aminobutyric acid neurotransmission may underlie cimetidine-induced seizures in mice.
TL;DR: The essential oil obtained from Heteropyxis natalensis by steam distillation was tested for antimicrobial properties and indicated the essential oil contained 1,8-cineole, limonene, β-myrcene, α-phellandrene and α-pinene.
Abstract: The essential oil obtained from Heteropyxis natalensis by steam distillation was tested for antimicrobial properties. Twenty five bacterial and four fungal species were used as test organisms in this study. These included animal and plant pathogens, food poisoning bacteria and mycotoxigenic fungal strains. The essential oil exhibited considerable inhibitory activities against all the test organisms. GC–MS analysis indicated the essential oil contained 1,8-cineole, limonene, β-myrcene, α-phellandrene and α-pinene.
TL;DR: The antibacterial and antifungal properties of the methanol, citric acid, aqueous, dichloromethane and petroleum ether extracts from the bark of Dalbergia melanoxylon were determined by using seeded agar plates with wells into which were placed the extract, and flasks of yeast extract and sucrose broth for mycelial growth of the fungi.
TL;DR: In this article, the impact of discharges from a fertilizer plant on the quality of the upper Mukuvisi River water was studied between the months of January 1989 and September 1990.
Journal Article•
TL;DR: Hydro-distilled volatile oil from the aerial parts of the plant was tested for antifungal activity against 10 fungal species using the dry weight method and showed significant activity against Aspergillus ochraceus, Candida albicans, Alternaria alternata, Geotrichum candidum, As pergillus niger, Penicillium citrium and AsperGillus parasiticus.
Abstract: Anemisia afra is indigenous to the eastern highlands of Zimbabwe where it is used in folk medicine. Hydro-distilled volatile oil from the aerial parts of the plant was tested for antifungal activity against 10 fungal species using the dry weight method. The results obtained showed that the essential oil exhibited significant activity against Aspergillus ochraceus, Candida albicans, Alternaria alternata, Geotrichum candidum, Aspergillus niger, Penicillium citrium and Aspergillus parasiticus.
TL;DR: It is considered the possibility that sperm competition has contributed to the evolution of the mating system in this species and mating was size-selective probably as a consequence of female choice.
Abstract: Field and laboratory observations of mating behaviour in a population of the tropical millipede Alloporus uncinatus were carried out over one breeding season. Males obtained mates through random encounters and by forming triplet associations with copula pairs. The occurrence of triplet associations in the field was coincident with a highly male biased operational sex ratio. Mate acquisition by males was apparently stochastic and direct physical competition did not occur. In laboratory experiments mating was size-selective probably as a consequence of female choice. We consider the possibility that sperm competition has contributed to the evolution of the mating system in this species.