School of Agricultural, Earth and Environmental Sciences

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Investigation of growth potential of alternative eucalyptus species for mid and high altitude sites in the summer rainfall region in South Africa.
(2008) Otim, Christopher Komakech.; Laing, Mark Delmege.
A study was undertaken to compare growth potential of three Eucalyptus species of natural origin in South Eastern Australia, with commercially grown species on mid and high altitude temperate sites in the summer rainfall growing zones in South Africa. The three species were Eucalyptus globulus subsp. bicostata (E. bicostata), Eucalyptus cypellocarpa and Eucalyptus nobilis. Nine sites were selected to represent the growing areas of South Africa experiencing cold winter drought with occasional snow falls. Improved, commercially grown pure Eucalyptus species and interspecific hybrid clones were included as controls in the trials to give comparative growth performances on specific sites. Both balanced and unbalanced lattice designs were used to evaluate the growth potential of the unimproved Australian species and the improved commercial controls incorporated into the trials. Volume production and basal area growth were assessed for the three species at all sites. However, only three sub species E.globulus (E. bicostata, E. maidenii and E. globulus) showed varying levels of disease (Mychosphaerella nobilosa) infestation and this was therefore assessed in trials at 12 and 30 months respectively, and correlation analysis was used to study the relationship between the impact of disease infestation and growth performance. It was found that negative phenotypic correlations existed between the levels of infection and tree growth. ie greater infection slower growth. Evaluation of genotype x environment interaction (GXE) revealed that this did not exist in the E. bicostata nor E. nobilis populations, and therefore one population of each species can be developed for all the sites tested. E. cypellocarpa was the only species that showed some GXE interaction implying that separate populations to be developed for different sites. Contrary to what was expected, unimproved Eucalyptus species being investigated performed equally as well as the improved commercial species included as controls, thus providing potential for commercial deployment with selection and breeding.
Occurrence of cowpea aphid-borne mosaic virus and prospects of improving resistance in local cowpea landraces in Uganda.
(2007) Orawu, Martin.; Melis, Robertus Johannes Maria.
Viral diseases are a major limiting factor to cowpea production in many countries of Africa. In Uganda, studies indicated that the cowpea aphid-borne mosaic virus (CABMV) is common and a potential threat to cowpea production in the region. There have been no efforts to develop cowpea cultivars with resistance to CABMV in Uganda. This work focused on the development of cultivars resistant to CABMV. Production of cowpea in Uganda is constrained by several factors, including a lack of awareness of diseases among the majority of farmers. A participatory rural appraisal (PRA) was conducted to elicit farmers’ indigenous knowledge of cowpea production and also to gain insight into their understanding of viral diseases affecting cowpea in Uganda. PRA tools such as group discussions, transect walks, problem listing and ranking were used to gather information. Insect pests, diseases, low yielding cultivars and the high cost of pesticides were perceived to be the most important production constraints. Farmers were not aware of the problem of virus diseases, but provided descriptive names of symptoms. Only three cowpea cultivars (Ebelat, Ecirikukwai and Blackcowpea) were produced in the area. Seed size and colour were seen as important traits in new varieties. Information about the occurrence, distribution and identity of cowpea viruses is limited in Uganda. The objective of this study was to identify the important cowpea virus diseases occurring naturally in the major cowpea growing regions of Uganda. Surveys were conducted to determine the incidence and severity of virus symptoms in four districts (Soroti, Kumi, Pallisa and Tororo) in 2004 and 2005. The incidence ranged from 40.5 to 94.4% and severity ranged from 15.0 to 30.6% (for Kumi and Pallisa districts, respectively) during the 2004 surveys. In 2005, the incidence ranged from 55.9 to 85.4% and severity ranged from 4.7 to 14.5% (for Tororo and Soroti districts, respectively). The CABMV, cowpea mild mottle virus (CPMMV), cowpea severe mosaic virus (CPSMV) and cucumber mosaic virus (CMV) were serologically detected by double antibody sandwich enzyme- linked immunosorbent assay (DAS-ELISA). Fifty four improved cowpea genotypes were screened for resistance to CABMV during the first season of 2004 at Serere Agricultural and Animal Production Research Institute in Uganda. Further screening was conducted in the second season of 2004 using 27 genotypes. The genotypes were planted in single rows between the rows of the susceptible cultivar, Ebelat. This was to provide high pressure of aphid vector (Aphis craccivora Koch) and CABMV inoculum. In addition, the test genotypes were artificially inoculated with a CABMV extract on fully expanded primary leaves of fourteen day-old seedlings. The CABMV incidence and severity was assessed. Disease severity was assessed on a 0-60% visual estimation scale where 0 = with no symptoms and 60 = with severe symptoms. Serological analysis was conducted using DAS-ELISA. Five genotypes showed good levels of resistance to CABMV, namely MU-93, IT82D-889, IT82D-516-2, IT85F-2841 and SECOW-2W. These resistant lines were crossed with three susceptible local landraces, namely Ebelat, Ecirikukwai and Blackcowpea in a North Carolina II mating design. The F1, F2 and BC1F1 populations and the parents were evaluated in the field to assess the response to CABMV and to study the inheritance of resistance to CABMV. The general combining ability (GCA) and specific combining ability (SCA) effects were significant, indicating that both additive and non-additive genetic factors are important in determining the control of CABMV in cowpea. The proportions (%) of the sum of squares for crosses attributable to GCA and SCA for CABMV severity were 51.4% for GCA due to females, 8.4% for GCA due to males and 40.2% for the SCA. The narrow-sense heritability estimates, obtained by regressing F1 on mid-parents was 0.87 and 0.84, F2 on F1 progenies 0.49 and 0.48, and F2 progenies on mid-parents 0.63 and 0.79, for AUDPC and final disease severity, respectively. Single gene conditioned resistance in seven populations, but resistance was quantitatively inherited and involved many genes in eight populations. Observation of transgressive segregation and moderate to high heritability suggests a quantitative mode of gene action and the importance of additive effects. The predominance of GCA variance, high heritability estimates and observation of transgressive segregation suggested that resistance could be improved by selection.
Breeding investigations of finger millet characteristics including blast disease and striga resistance in Western Kenya.
(2008) Oduori, Chrispus O. A.; Derera, John.; Tongoona, Pangirayi.
Finger millet (Eleusine coracana (L.) Gaertn. ssp. coracana) is an important food, food security and cash crop in eastern and southern Africa where small-scale farmers grow it in low input farming systems. The crop has food security, nutritional, cultural, medicinal, and economic value with high industrial potential. Little research and hardly any breeding have been done on the crop leading to low yields and low production. A project was therefore implemented in western Kenya during 2004-2007 seasons to investigate the possible breeding contributions to enhance productivity and production of the crop. The research comprised a social survey, germplasm evaluation, appraisal of ethrel as a chemical hybridising agent (CHA), genetic analysis of yield, and resistance to blast and Striga, and breeding progress in developing new finger millet varieties. A participatory rural appraisal (PRA) was conducted in three districts during 2006 to position finger millet (FM) in the farming systems, production constraints, and variety diversity and farmer preferences. The PRA established the high rating the peasant farmers gave to finger millet among crop enterprises, using it for food, cash, brewing, ceremonies and medicinal purposes. Farmers cultivated many varieties ranging from five to nine in a district, but each district had its own popular variety. Farmers used the following criteria to select new cultivars: high yield potential; early maturity; resistance to blast disease, Striga, birds, drought, and lodging; large head size, dark grain colour, and good taste. This probably indicated the willingness of farmers to adopt new varieties. Farmers identified constraints to production as blast disease, Striga, wild FM, birds, rats, termites, lack of market, labour shortage, and low yield. The farmers’ variety selection criteria and production constraints underscored the need to improve finger millet varieties. Evaluation of 310 accessions for trait variability and association conducted during 2005 long rain (LR) season at two sites revealed wide variation among the accessions for yield and secondary traits. The best accessions grain yield was above the yield potential of 5,000- 6,000kg ha-1 reported in other environments. Accessions KNE 072 (7,833kg ha-1), GBK 028463 (7,085kg ha-1), GBK 029661 (6,666kg ha-1) and FMBT ACC#42 (6,566kg ha-1) were outstanding. The data showed the opportunity to select for yield directly because of its wide variability but indirect selection could also be used to exploit seedling vigour as shown by its high correlation to yield and direct and indirect positive effects on yield through plant height and single plant yield in path analysis. The wide genetic variability among the genotypes for several traits indicated high potential to breed new and better finger millet varieties.
Cowpea seed quality in response to production site and water stress.
(2007) Odindo, Alfred Oduor.; Modi, Albert Thembinkosi.; Southway, Colin.
Cowpea (Vigna unguiculata. L) is an important African crop. However, it is also an underutilized grain legume. Consequently, there is not enough research data on cowpea seed physiology. Whereas there is evidence of cowpea being a drought tolerant crop, there is no evidence to associate plant drought tolerance with seed quality in response to water stress. This study sought to understand the effect of production site and water stress on cowpea seed quality development with respect to germination capacity and vigour. Patterns of raffinose family of oligosaccharides (RFO) during seed development to mature dry stage were used to physiologically relate seed performance to water stress. The effect of water stress and exogenous ABA on the accumulation of stress LEA proteins (dehydrins) in relation to seed quality development and germination was investigated. RFOs are known for their roles in desiccation sensitivity but no studies have shown their significance in cowpeas. Seeds of six cowpea cultivars were produced at two distinct growth sites characterised by irrigated and dry land conditions. The seeds were assessed during six developmental stages, for water content, dry matter accumulation, and performance. Harvested seeds were then planted in a pot experiment under controlled conditions to examine the effect of water stress on seed quality development and data collected during three developmental stages. Harvested seeds from the pot experiment were subsequently analyzed for changes in RFO accumulation during development using gas chromatography. The seeds were also used to investigate the effect of water stress and ABA on the accumulation of stress LEA proteins (dehydrins) in relation to seed quality development in cowpea. In addition, this study evaluated the use of image analysis as a method that can be used to objectively determine seed coat colour variation in cowpea. Statistical variation in individual seed’s solute leakage for cowpea cultivars differing in seed coat colour and produced under different environmental conditions was explored and correlations were done between seed conductivity test with other aspects of seed performance during germination. Furthermore the results of the conductivity test were compared with accelerated aging test, in relation to seed performance. The study provided evidence that cowpea seed lots produced under different environmental, and possibly management conditions may not differ with respect to seed quality as determined by germination capacity and vigour. However, significant differences between sites with respect to seed maturation patterns determined by water content and dry matter accumulation were observed. Adverse maternal environmental effects on the subsequent performance of seeds in a drought tolerant crop may not necessarily lead to poor performance. Cultivar differences in response to simulated drought conditions at the whole plant and tissue level can be considerable and highly variable; however, these differences may not have adverse effects on the germination and vigour of the seeds. Drought avoidance mechanisms at the whole plant level in cowpea are quite efficient in allowing the species to adapt to simulated drought conditions. These mechanisms may allow the cowpea cultivars to maintain metabolism and restore conditions for their continued growth under water stress; and produce few seeds of high germination capacity and vigour. Stachyose was found to be the predominant member of the raffinose family of oligosaccharides in cowpea. It is suggested that stachyose accumulation could be used as an indicator of stress tolerance in cowpea. However, the relationship between RFO concentration and the acquisition of desiccation remained as a matter of speculation in the present study and is still generally inconclusive. There was no evidence to suggest the acquisition of maximum desiccation tolerance is associated with maximum seed vigour. It is suggested in cowpea, which is drought tolerant, that maximum vigour does not necessarily imply the acquisition of maximum desiccation tolerance; rather there is a minimum level of desiccation tolerance that is required for the development of optimal seed vigour. The use of an in vivo approach in the study of LEA function in cowpea enabled the accurate comparison of two different groups of LEA proteins in developing cowpea seeds under conditions of water stress and in relation to germination and vigour. Both group 1 LEA and group 2 LEA (dehydrin) were shown to increase in concentration in response to water stress. In addition group 1 LEA protein was observed to be relatively abundant in cowpea seeds. A maternal influence on LEA protein gene expression under conditions of water stress, which may induce dehydrin accumulation vii during the earlier stages of seed development, was implied by the observation that dehydrin-like proteins were induced after two weeks of development in cowpea plants subjected to stress during the vegetative phase. In addition, the exogenous application of ABA delayed radicle protrusion; this was associated with a delay in the disappearance of LEA proteins and is suggestive of a relationship between LEA protein accumulation and the acquisition of desiccation tolerance. The study has demonstrated that image analysis can objectively discriminate seed coat colour variation in cowpea. Dark coloured seeds in general performed better than light coloured seeds; however seed coat colour was not always associated with better performance. A newly developed Aging Stress Differential Index (ASDI) has been used in this study to demonstrate a link between seed coat colour and sensitivity to water stress. The ASDI correlated well with the observations relating stress tolerance to stachyose accumulation. The skewed distribution patterns in individual electrical conductivity and the presence of extreme values may have implications with respect to the suitability of using standard statistical analyses which compare mean values to evaluate such data. In addition variation in individual electrical conductivity may also be influenced by cultivar differences and the chemical composition of the seed coat. Therefore associations between seed coat colour and electrical conductivity as a measure of performance should be treated with caution. The AA test does reflect changes in seed vigour, however ranked electrical conductivity values after AA did not consistently reflect differences in seed performance between cultivars and sites, and they did not correlate well with other aspects of performance.
The influence of soil properties on the vegetation dynamics of Hluhluwe iMfolozi Park, KwaZulu-Natal.
(2009) Harrison, Rowena Louise.; Hughes, Jeffrey Colin.
The physical and chemical properties of soils can greatly influence the vegetation patterns in a landscape. This is especially so through the effect that particular characteristics of soils have on the water balance and nutrient cycling in savanna ecosystems. Areas in the savanna environment found in Hluhluwe iMfolozi Park have experienced a number of changes in the vegetation patterns observed. This study, therefore, looks at the effect that soil characteristics may have on the vegetation growth in this area and on the changes that have taken place over time. Fixed-point photographs, taken every four years, were used to choose fourteen sites in the Park, which showed either a ‘change’ or ‘no-change’ in vegetation from 1974 to 1997. The sites consisted of four which had ‘no-change’ in vegetation, two sites with a slight increase (5- 20%) in tree density, three sites with a greater increase in tree density (>20%), two sites with a slight decrease in tree density (5-20%), and three sites with a greater decrease in tree density (>20%). Transects were then carried out at each site, in which the soil was classified to the form and family level. Each horizon was then sampled and the field texture, structure, Munsell colour and depth of each horizon and profile recorded. The data recorded in the field were statistically analysed through a principal component analysis (PCA). The type of horizon, horizon boundary, structure type, colour group and depth for the top and subsoil were included in the models and were analysed with the number given to each site for each of the three sections of the Park, namely Hluhluwe, the Corridor and iMfolozi. The most prominent textures at all sites were sandy loam, loam, clay loam and silt loam for both the top and subsoil for all site categories. The texture classes were also compared across the Hluhluwe, Corridor and iMfolozi sections. The dominant textures in the Hluhluwe and Corridor sections are loam, clay loam and silt loam for both top and subsoils. Sites sampled in the iMfolozi section appear to have textures mainly associated with the clay loam and sandy loam classes. The structure classes of the soil including sub-angular blocky, granular and crumb which are associated with a moderate structure appear to be the most dominant type in all categories for the topsoil; single-grain and sub-angular blocky classes the main types for the subsoil. Generally the colour of the soil at all the sites sampled was yellower than 2.5YR and the values and chromas mostly fell within the range of 3-5 and 2-6, respectively. This is also shown in the PCA results obtained, which associate particular soil characteristics with the various sites sampled for the different vegetation change categories investigated. The samples collected were also analysed in the laboratory after being air-dried. The laboratory analysis included measurements of pH, exchangeable acidity, organic carbon, extractable phosphorus, particle size distribution and cation exchange capacity (CEC). The data recorded in the laboratory were also analysed by PCA. This was used to determine which soil properties are associated with the particular sites investigated. The pH of the soil, in all areas, fell within a wide range. The pH is influenced by the rainfall in the area and thus sites sampled in the Hluhluwe section are more acidic than those sampled in the Corridor and iMfolozi sections. The topsoils had a higher pH for all the samples and were in the range between 5 and 7. The exchangeable acidity measurements were low, although they were higher in the subsoil as opposed to the topsoil. The nutrient contents did not appear to vary greatly between the different sites in the Park. Generally extractable phosphorus, CEC and organic carbon were low across the Park. The particle size analysis showed that the clay percentage increases between the top and subsoil for all the sites sampled. The silt and various fractions of sand percentages vary across all sites and are lower than the clay percentage at all sites except the A horizon of the ‘slight increase’ sites. The ‘no-change’, and ‘increase’ sites have a higher percentage of clay as compared to the silt and sand fraction for both the A and B horizon. The ‘slight increase’ sites have a higher percentage of sand in the A and B horizon, the ‘slight decrease’ sites have a more equal percentage between the sand, silt and clay fractions in the A horizon and a greater percentage of clay in the B horizon. The ‘decrease’ sites have a greater percentage of clay and silt in the A and B horizon. While certain soil properties have a definite effect on the plant growth, no relationship between specific soil properties and vegetation changes was shown. However, it is likely that the soil structure and texture affect the vegetation patterns, through their influences on the water and nutrient holding capacity. With an increase in the clay percentage and more strongly structured soils, plants can access more water and nutrients and this will increase the tree density in an area. However, the recent changes in the vegetation patterns observed in the Park appear to be more associated with other environmental factors. The soil properties analysed would have generally been more constant at the sites sampled, particularly over the relatively short period of time in this study. Therefore, the changes which were recorded in the fixed-point photographs would have been enhanced by other factors experienced in the Park, including fire and the effect that grazers and browsers have on the vegetation.
The use of spatial analysis and participatory approaches in strategic environmental assessment (SEA) : identifying and predicting the ecological impacts of development on the KwaZulu-Natal North Coast of South Africa.
(2010) Ahmed, Fathima.; Bob, Urmilla.; Ahmed, Fethi B.
The high pressures for coastal development, translated as prolific land cover transformation, coupled with the weaknesses of management to protect the environment has led to the gradual deterioration of environmental conditions in many coastal areas. Land use decisions in coastal areas are based on opportunities and constraints affected by both biophysical and socio-economic drivers, and hence present one of the main issues integrating the large debate on sustainable development in coastal zones (Lourenço and Machado, 2007: 1). The aim of this study is to investigate the effectiveness of the integration of spatial analysis and participatory approaches in SEA (particularly its ability to identify and predict ecological impacts) on the KwaZulu-Natal north coast of South Africa. The study adopted a conceptual framework based on landscape ecology, which was underpinned within the overarching political ecology framework. The former underscores the importance of integration, while the latter critiques the institutionalization of environmental concerns, which are characterized by inequalities in terms of social and political power and of how problems are defined, mediated and resolved. Hence this conceptual framework was considered appropriate to assess the strategic environmental issues pertaining to the coastal zone on the KwaZulu-Natal north coast. The researcher used participatory methods, primarily focus group discussions (which included venn diagramming, ranking exercises and participatory mapping) which were triangulated with both quantitative and qualitative methods as part of an integrated impact assessment. These relate to the use of semistructured questionnaires which were administered to a purposive sample of six key stakeholder interest groups within the study area. A spatial GIS time series analysis of land use and cover change was employed to determine baseline conditions, changes in the state of key ecosystems, key development drivers and emerging threats. Additionally, a policy and institutional review was undertaken. The analysis revealed that major natural land cover classes are in decline in the study area,within a time period of less than 10 years. The most sensitive ecosystems were found to be grasslands (-19.99%), coastal forest (-40%), wetlands (-37.49%) and secondary dunes (- 21.44%). Furthermore, agriculture and forestry are also indicating severe declines. The reasons attributed to this transformation of land cover are increasingly being linked with economic motives such as individual private land-owner dynamics, tourism growth and development in the area. Furthermore, the policy agendas are clearly economically motivated. These losses signify the cumulative decline in ecosystem goods and services, and could undermine pose risks to the society that relies on them either directly or indirectly. One of the main considerations in this research endeavor was to formulate a Strategic Environmental Assessment (SEA) Framework to inform future ICZM in the study area. SEA is planning with a long-term perspective, with a focus on a spatial rather than a project level, an element that is clearly lacking in the current development scenario of this coastline. It is critical that the SEA Framework advocated in this study include a range of variables that will permit short-term, medium-term and long-term monitoring and evaluation aimed at ensuring sustainable planning in the area.
Globalisation, development and community-based tourism in developing countries : a case study of Pondonland, Eastern Cape.
(2010) Giampiccoli, Andrea.; Moodley, Vadivelu.; Brooks, Shirley.
Contemporary globalisation in developing countries is circumscribed by neo-liberal development approaches, while community-based development seeks to create alternative development strategies. This thesis brings together research in tourism with theoretical perspectives from Gramscian social analysis in order to explore contemporary conflict between these two strategies in the tourism sector. The purpose is to investigate the influence the hegemonic global milieu has exerted on an alternative community-based tourism (CBT) strategy that was initially formally/institutionally supported. Concepts of hegemony, globalisation and divergence/convergence, together with development theories, are explored and applied to the international tourism sector and CBT in particular. A theoretical structure is proposed in which the relationships between hegemony, globalisation, and processes of divergence/convergence are explicated in relation to the tourism sector, and CBT in particular. Global-local linkages, conceptualised in terms of the theoretical framework, are explored in a particular geographical context, namely the Pondoland coast of South Africa. South Africa has recently rejoined the global socio-economic milieu after the isolation of the apartheid period and a European Union-supported tourism project in the Pondoland region is studied in detail. The case study serves to empirically substantiate the proposed theoretical framework. The investigation contributes to ‘initiate’ a global – local oriented paradigm in tourism study that focuses on the relationship between globalisation processes and a CBT development approach by exploiting and conjoining the correlation of the concepts of the proposed theoretical framework. Globalisation processes are set against a specific and local form of tourism, i.e. community-based tourism. The proposition is a ‘new’ double level of interlinkage. General and global policies are interlinked and cross each other with specific and local policies to evaluate a CBT project outcome. The study intends to go beyond existing literature of CBT management and project development. This is achieved by providing an investigation on the ‘unseen’ working mechanisms and influence of globalisation processes in relation to a specific CBT local project supported by a global actor in international cooperation, thus verifying interpretations and commitment on CBT development approaches. The case study findings elucidate and highlight the final effects of the theoretical proposition at a practical level by clarifying and showing the level of influence on, and re-adjustment of, the case study end result in comparison with its initial plan. A shift in the case study project development is individuated and commented on in relation to the proposed theoretical framework. The investigation results allow validating the proposed conceptual basis of the study. Based on the findings, this thesis a proposal is made to construct the interrelationship between development and CBT understanding. A typology and specific nomenclature of CBT approaches is advanced together with their correlation to development concepts. The conclusion also gives further general and specific recommendations by providing possible strategies to permit proper development and better exploitation of CBT possibilities.
The impact of food aid on maize production in Swaziland.
(2007) Mabuza, Majola Lawrence.; Hendriks, Sheryl Lee.; Ortmann, Gerald Friedel.; Sithole, Moses M.
The objective of the study was to provide empirical evidence on whether food aid leads to depressed domestic maize prices and reduced maize production in subsequent years in Swaziland. Similar impact studies have been carried out in a number of sub-Saharan African countries but no evidence is available for Swaziland. The lack of empirical evidence has often resulted in premature negative conclusions on the impact of food aid on Swaziland’s maize industry. The study used secondary national data from 1985 to 2006 to analyse the impact of food aid on maize producer prices and quantity of maize produced. Variables used in the analysis included quantity of cereal food aid; quantity of commercial maize imports; quantity of locally produced maize; official maize producer price; open market maize producer price; fertilizer price; fuel price; rainfall; and total area planted to maize. The impact of food aid was measured using the reduced form market equilibrium model that consisted of maize quantity and maize producer price functions estimated simultaneously using the above variables through the two-stage least square method (2SLS) method. Analytical results revealed that food aid to Swaziland does not lower prices of domestic maize and has no significant negative effect on the quantity of maize produced in subsequent seasons. This means that food aid received by Swaziland over the study years has been appropriately targeted and distributed to the food insecure households. If this were not so, the demand for food from commercial outlets would have been reduced, leading to an adverse impact on maize producer prices, and subsequent local maize production. Notwithstanding the above results, Swaziland should still commit resources towards reducing the national food gap. This calls for increased investment in rural irrigation development, improved farmer institutional support services, and the implementation of pro-poor development programs aimed at improving individual household income to reduce the need for food aid, improve food self-sufficiency and vulnerability to food security.
Improving resistance to Fusarium root rot [Fusarium solani (Mart.) Sacc. f. sp. phaseoli (Burkholder) W.C. Snyder & H.N. Hans] in common bean (Phaseolus vulgaris L.)
(2008) Mugisha, Clare Mukankusi.; Melis, Robertus Johannes Maria.; Derera, John.; Laing, Mark Delmege.; Buruchara, Robin.
Fusarium root rot (FRR) disease, caused by the fungus Fusarium solani f. sp. phaseoli (FSP), is an important soil-borne disease reducing common bean (Phaseolus vulgaris L.) yields, and hence food security, in Uganda and elsewhere in developing countries where the crop is grown without fungicides. The key aim of this study was to elucidate the significance of bean root rot (BRR), appraise methods for screening germplasm for resistance to FRR, determine the genotypic variability of resistance, and the inheritance of resistance to FRR in common bean. This information was deemed useful in devising an appropriate strategy for breeding FRR resistance in beans. A participatory rural appraisal (PRA) was conducted in south-western and eastern Uganda to ascertain farmers’ awareness of BRR and their influence on preferred bean varieties. Bean root rot is considered to be the most devastating and most recognised disease, especially in south-western Uganda. Control measures for BRR were very minimal, and in some cases, non-existent. Use of resistant varieties to control the disease was not evident, because the most popular varieties were susceptible to the disease. The resistant bean varieties currently available have undesirable characteristics such as small seed size, black seed and late maturity. Large-seeded bean varieties, even though cited as being more susceptible to BRR than the small-seeded varieties, are still very popular. The study highlighted the need for breeding FRR resistance in the large-seeded bean varieties that are highly preferred by farmers. Four isolates of FSP (FSP-1, FSP-2, FSP-3 and FSP-4) were tested for pathogenicity under screenhouse and laboratory conditions. In addition, three methods of storing and maintaining the viability of FSP isolates were appraised. The isolate FSP-3, was found to be the most pathogenic, resulting in 100% disease incidence on all bean varieties tested, with high severity scores. The potato dextrose agar (PDA) slants stored at 5oC were found to be the best method of storage for pathogenic isolates. The FSP-3 isolate was subsequently utilised for screening bean lines for resistance to FRR. The influence of soil composition, irrigation frequency, and inoculation technique on the severity of FRR was studied on six bean lines. Interactions of irrigation frequency, soil composition, and bean lines were not significant. The 50% swamp soil:50% forest soil composition and forest soil alone categorized the varieties most distinctly according to their reaction to FRR. Also, the best distinct classification for the varieties was obtained under treatments that were watered daily and once in a week. Based on economic considerations, the standard forest soil and daily irrigation were subsequently adopted for screening bean germplasm for resistance to FRR. It was also found that sorghum seed as a medium for pathogen inoculation was better than the agar slurry medium. One hundred and forty seven common bean varieties were evaluated for resistance to FRR (isolate FSP-3) under screenhouse conditions. In order to confirm this resistance, 46 common bean lines selected from the screenhouse trial were further evaluated using natural inoculum in a BRR-infested field. Forty-four varieties comprising ten large-seeded, four medium-seeded and 30 small-seeded varieties showed moderate resistance to FRR; but none were resistant or immune to the disease. Based on adaptability, eight moderately resistant varieties were selected for use as parents in the study of inheritance of resistance to FRR. A 12 x 12 diallel mating design was utilised to develop 66 F1 and F2 populations, plus their reciprocal crosses, with the aim of studying the mode of inheritance of resistance to FRR. The F1 and F2 progeny evaluations showed that FRR resistance was mainly governed by additive genes in most populations. However, there were a few crosses which displayed highly significant specific combining ability (SCA) effects, implying that dominant effects were important in some populations. Maternal effects were also highly significant at both the F1 and F2 generations, suggesting that resistance was modified by cytoplasmic genes. The non-maternal effects were also significant in some populations, suggesting that the cytoplasmic genes were interacting with nuclear genes. The number of genes governing resistance to FRR varied from two to nine among the eight sources of resistance. The allelism test of resistant x resistant populations, and the observation of continuous distributions of severity scores, suggested the presence of many loci governing FRR resistance in beans. Broad sense heritability of disease resistance varied from 0.22-0.69, while heritability in the narrow sense was estimated as 0.35-0.49 in the populations. These results suggested that selection and backcrossing to both parents would be the best breeding procedures for improving resistance in the popular large-seeded bean varieties in Uganda. However, there could be complications in breeding for resistance to FRR in beans, because resistance was modified by cytoplasmic gene effects and their interaction with nuclear genes in some of the populations.
Assessing the feasibility of land reform farm equity schemes : a focus on capacity building and empowerment
(2006) Phayane, Gwendoline Mosela.; Rugege, Denis.
This research was undertaken to determine the extent to which share equity schemes have been successful. The research also investigated the possible causes of failure of the established share equity projects and sought to determine the feasibility requirements that may be put in place to ensure success and sustainability of the ventures in support of land reform. The methodology used involved comparing the data gathered from business plans, valuation reports and other project documents from the Department of Land Affairs (DLA) with the information gathered through interviews and observations. The results revealed causes of failure to include the fact that beneficiaries of the investigated equity schemes did not participate in business plan development or implementation and therefore had no sense of ownership in the intended joint ventures. It was also found that none of the business plans included any form of training for capacity building and therefore no mechanism for empowering beneficiaries existed to participate effectively at all levels of the farming enterprise. Furthermore, original farm owners as the majority shareholders tended to re-invest profits into farm assets rather than paying dividends. It was concluded that the inclusion of a training programme in every business plan is crucial to the success of farm share equity ventures as this may enable beneficiaries to be sufficiently empowered to participate effectively at all levels of the business.
The long-term measurement of total evaporation over Acacia mearnsii using large aperture scintillometry
(2007) Clulow, Alistair David.; Savage, Michael John.
A large aperture scintillometer (LAS) was operated continuously over a distance of 575 m from 19 August 2006 to 29 September 2007 in the South African KwaZulu-Natal midlands mistbelt area over Wattle (Acacia mearnsii). The LAS measurements of the structure parameter of the refractive index of air ( 2 n C ), were used to calculate the sensible heat flux. The shortened energy balance equation was used to estimate the latent energy flux as a residual from which the total evaporation (ET) was calculated. The LAS estimates of sensible heat flux during the short transition period (1 hour) between stable and unstable conditions were on occasion erroneous and required verification. Advection was also found to affect sensible heat flux estimates. Long-term operation of the LAS was however found to be possible even at remote sites, producing reliable and continuous results. The LAS estimates of sensible heat are sensitive to zero-plane displacement height and wind speed data impact and these should be derived as accurately as possible. Tree heights were measured at monthly intervals and a zero-plane displacement and effective height were calculated every two weeks. The sensible heat flux was thus processed in two week blocks of data corresponding to progressive effective heights. The tree growth rate was consistent over time and was not affected by seasonality, indicating that reduced air temperatures, rainfall and solar irradiance in winter are not limiting growth. The average growth rate was 0.37 m per month or 4.5 m per year. The LAS ET was compared to the American Society of Civil Engineers - Environmental and Water Resources Institute (ASCE-EWRI) short grass reference evaporation (ETsz) for a seven-month period and was found to compare favourably (R2 = 0.78) with outliers caused by advection and rainfall events. Calculations of grass reference evaporation at hourly and daily intervals provide different results. The daily estimates are lower than the hourly estimates by 17 % on average. Where hourly data is summed to calculate a daily ETsz, night-time values should be included. The LAS ET measurements were validated against the Priestley and Taylor (1972) method of estimating ET and found to be in good agreement (R2=0.94). The Priestley and Taylor daily total latent energy flux, from 22 August 2006 to 29 September 2007, was 9 % higher than the LAS results on average. The Bowen ratio for the entire period is less than 1, indicating that the latent energy flux dominates at the site. The ET over the period of measurement (13 months) is 1250 mm and the rainfall is 750 mm. This confirms previous results at the site using the Bowen ratio energy balance method showing that the ET exceeds the rainfall by 45 % and justifies further research into soil water, ground water and root interactions in the deep soil profile.
Trust-based relationships between parks and communities : a case study of the Obonjaneni community and the Royal Natal Park in the Drakensberg, KwaZulu-Natal.
(2008) Tsvuura, Susan Maira.; Fincham, Robert John.
The study was conducted in the Amazizi Traditional Administrative Council Area, in the Obonjaneni community, which is the closest community to the Royal Natal Park, KwaZulu-Natal. The aim of the research was to evaluate how trust-based relationships can affect the ability of protected area managers to meet the objective of biodiversity conservation. The objectives of the study involved determining the nature and basis of the current relationship between communities and park authorities in the Royal Natal Park; determining the resilience of their relationship and commenting on how these relationships might be better developed. Data collection was undertaken using focus groups from the community; key informant interviews with Park authorities (represented by the Officer in Charge), the Community Conservation Officer, and the Tribal Authority (represented by the inkosi). Three dimensions of trust, adapted from Grunig and Hon (1999), were used as a conceptual framework in investigating the extent to which trust can be assessed in the case study. The dimensions of trust are: integrity, competence, and dependability. The researcher found that there is no forum for the exchange of ideas where the Ezemvelo KwaZulu-Natal Wildlife (EKZNW) authority can act to address community concerns and facilitate the formulation of greater levels of trust. Several issues came up during data collection which showed that all the three dimensions of trust were under serious threat. There was inadequate communication amongst all the parties involved. Misunderstanding and the lack of adequate communication are key threats to trust between these parties. Findings draw attention to deficiencies in the competence and dependability of all parties and in the ability to develop and maintain trust-based relationships. In order to develop a better relationship between the community of Obonjaneni and the Royal Natal Park authorities, it is recommended that the Park involves the community members of Obonjaneni, who are the interested and affected party, in decision-making processes that directly affect them. This entails the formation of a forum for the exchange of ideas and one where the EKZNW authority can act to address community concerns – and where the community can voice its concerns. Furthermore, success in meeting the main objective of the park, that of biodiversity conservation; requires recognition among all stakeholders that the Park alone cannot solve poverty and underdevelopment in the surrounding areas. Other Government Departments also need to be involved in poverty reduction. The Park also needs to continue to play its role of providing resources and improving the communication with surrounding communities: these are critical areas of competency of the park authorities. Communities, because they have different levels of understanding and capacity, need to be helped to understand issues of conservation. Sharing the same set of values, which in this case is biodiversity conservation, may be successful if people, despite issues of poverty, are made to understand the critical importance of such a conservation ethic.
Managing relationships, learning and demands in protected areas : a social systems analysis.
(2007) Nkhata, Bimo Abraham.; Breen, Charles Mackie.; Fincham, Robert John.
This thesis seeks to contribute to the improved understanding of social systems analysis in management effectiveness research on protected areas. It develops and applies propositions for incorporating the analysis of social systems into management effectiveness research. The propositions are designed as theoretical constructs which represent some aspects of social reality in protected area management. They signify an organized way of thinking about the social domain of protected area management. It is argued that an analysis of management effectiveness must recognize the need to take into account the inherent interactive nature of the connections among three variables, relationships, learning and demands. It is suggested that the three variables do not exist in isolation, but are interconnected and exert influence on each other. The interactions among the variables provide this study with a conceptual structure for analyzing the social domain of protected area management. The thesis conceives the management of relationships as a behavioral process in which protected area management agencies influence the decisions and actions of other parties, and vice versa, over a period of time in order to advance shared interests. The effectiveness of relationship management depends on integrated learning, a collective process of managing information in a timely manner so as to enhance the responsiveness of social actors involved with protected areas. Demand management is viewed as a social process in which protected area management agencies develop timely and defensible responses to current and emerging demands from stakeholders. The management of demands is expressed through relationship management and integrated learning. Important in this context is the capability of social actors to cope with complexity, change and surprises. The thesis should be seen as a theoretical premise that focuses on the learning competence of social actors by aligning and fostering their ability to respond timely to the ever-changing demands on protected areas through the effective management of relationships. It should be viewed as making a contribution to the move in protected area management towards developing learning organizations and institutions through a systems approach. This should be interpreted as enhancing learning about the human dimensions of protected area management. And more specifically, effective learning generates timely responses in the management of demands and relationships. The implications of failure to respond quickly enough are epitomized in a number of South African examples such as rivers that stop flowing and conflicts over resource use. The thesis makes a contribution to management effectiveness research by examining in some important ways why research should not be determined solely by biophysical components, but should be extended to the broader social issues that define the nature and quality of management. It is argued that a deep appreciation of management effectiveness requires an understanding of relationships, learning and demands to provide a foundation for systemic social analyses. The thesis illustrates why a behavioral approach to relationships theory provides a foundation for resilient social relationships in collaborative processes. It shows why the establishment and maintenance of an integrated learning system take place in a complex context which links elements of governance learning and management learning. It also evinces why protected area management agencies have to incorporate mental models into adaptive management of demands. These insights imply that the opportunities for effective protected area management are largely contingent on systemic insights into the underlying social structures and processes responsible for emergent problems. By exposing the insights, research on management effectiveness is poised to take new direction.
An assessment of community understanding of the Human Animal Conservancy Self-Insurance Scheme and the impact of human-wildlife conflicts : a case study from the Kwandu conservancy, north-east Namibia.
(2006) Kasaona, Marthin Kaukaha.; Dent, Mark Clifford.
The research problem of this mini-dissertation involves the conflicts between human and wildlife populations and the trialing of ‘compensation’ payouts that are emerging as a critical test within the conservancy. Crop raiders such as elephants, buffaloes, hippopotamus, bush pigs and small rodents, diminish farmers’ resource bases and cash crops, while carnivores are responsible for livestock losses. The aim of the research is to assess the level of community understanding of the compensation scheme and the impact of human wildlife interaction within the conservancy. This mini-dissertation investigated the level of community understanding about the Human Animal Conservancy Self-Insurance Scheme (HACSIS), and the impact of human-wildlife conflicts within the Kwandu Conservancy. Some of the research data were obtained from the conservancy game guards’ event book system, and the actual field research data were collected from the 1st August to 20th August 2006. The researcher conducted a total of 35 interviews, whereby 32 involved face-to-face interviews with single individuals, and 3 separate focus group discussions that consisted of four, five and two conservancy members. The interviews averaged 30 minutes in length. Each interview was preceded by a careful explanation of the purposes of the work, stressing that the intent was to evaluate their understanding and perceptions on HACSIS, the impact of human-wildlife conflicts and to explore better management strategies. The researcher has taken into account that the communities might exaggerate the wildlife problem based on his previous experience with the adjacent conservancy, in the hopes of gaining more compensation – they also use the researcher as a way to vent their frustration at the problem. On the assumption that there may be an element of exaggeration verification of these was obtained from the Event Book System (a manual book used by the Community Game Guards for recording both crops and livestock incidents on daily basis). This mini-dissertation reveals that 74.3 % (n = 26) of respondents are aware of the existence of the HACSIS program and its role, while 17.1 % of respondents had no idea about the scheme’s presence and its involvement to minimize the impact felt by communities when they lose livestock to predators. The percentage of respondents who claimed that they had heard of the scheme’s existence but had no knowledge of its role was 8.6 %. In addition, most respondents (n = 15) claimed that the conservancy committee did not explain to them why their claim forms were rejected. In contrast, some respondents (n = 6) did received feedback on rejected claim forms. HACSIS was not formed to compensate livestock losses based on market value, nor was it intended as a ‘compensation’ scheme. Its aim was to test a conservancy-run process – local verification of claims and monitoring by conservancy committee and traditional authority. In addition, the authorization of payments for a type of ‘self-insurance’ is drawn from conservancy income to partially offset the losses of conservancy members versus the overall gains that wildlife brings to the conservancy (direct conservancy income and local jobs through tourism, trophy hunting, own use game harvesting). Conservancy committees and the support NGO, IRDNC, agreed on the amount to be refunded for animal losses before the scheme was started, initially using donor funding in the trial phases. The amount was deliberately kept low as it was acknowledged from the start that conservancies themselves would take over the repayments from their own income. Once the conservancy was used to its own income to finance the scheme, conservancy members could vote to increase amounts paid for predator losses. The crucial aspect, according to IRDNC, was that the process itself be tested and that the scheme be run by the conservancy, with Ministry of Environment and Tourism and IRDNC merely monitoring and providing assistance as needed. Compensation is based on this pre-determined amount that is less than the livestock value. However, the research reveals that respondents (n = 19) were dissatisfied with the amount paid (N$ 800-00 per ox killed), because they claim that the amount paid to relieve the immediate impact from wildlife is too little to sustain the affected member. In contrast, some respondents (n = 8) were satisfied with the amount paid as compensation. Despite criticisms about the amount paid for livestock losses, none of the respondents (n = 22) who were familiar with the scheme wanted it to be abolished. The respondents emphasized the need for the conservancy committee to review the amount paid as compensation, especially for cattle. They suggested an increase from the current N$ 800-00 to N$ 1000-00 per ox loss. The research reveals that community livestock management practices have not changed to deliberately benefit from the compensation. In fact community management strategies have improved because of the condition set by the review committee dealing with the compensation scheme. Wildlife incidents have increased because animals are habituated to techniques used by communities to deter them and this has contributed to high livestock incidents. For human-wildlife conflicts, the research acknowledges that the conflict exists. Between 2003-2005, the Kwandu Conservancy reported 1508 incidents of damage to crops by wildlife. Species that were responsible included elephants with 30.2 % damage, bush pigs (29.8 %), hippopotamus (12.7%), antelopes (12.7 %), porcupine (7.5 %), and baboons/monkeys (7.2 %). Most of the crops destroyed by crop raiders, as suggested by the respondents, were maize (30 %), sorghum (26 %), millet (17 %), groundnuts (14 %), pumpkins (8 %) and beans (5%). During the same period of crop losses, the conservancy reported 98 livestock incidents. Animals responsible for livestock incidents were crocodile with 32 incidents (32.7 %), then hyena (23 incidents, 23.5 %), leopard (22 incidents, 22.4 %) and lion (21 incidents, 21.4%). The role of community game guards was found to be extensive. From a total 35 responses, 74.3 % (n = 26) of members stated that community game guards effectively record incidents, chased problem-causing animals from the community crop fields by shouting or shooting in the air, and assessed or verified killed livestock for compensation purposes. In addition, community game guards conduct crop assessment for record-keeping purposes. The scheme for crop compensation is to be introduced in 2007. Currently there is no proper formula to use in assessing the value of crops and the method to use to compensate the affected members. Other methods used by communities to deter wildlife include sleeping in the field to guard crops, cracking a whip, construction of human statues, hanging tins on the fence, chilli coils, watchtowers and digging trenches. Respondents had different views on the best management practices for problem-causing animals. The response was generally based on the degree of threat that the animal posed. Most (43.8 %, n = 14) preferred the monitoring of problem-causing animals that are sighted in an area as a best practice, while 40.6 % (n = 13) of respondents preferred the animal to be captured and relocated to parks. Only 25.6 % (n = 5) of respondents preferred that the animal be destroyed. The management practices preferred by respondents when an animal kills a person are different from when an animal is simply sighted in the area. If an animal kills a person, only 12.5 % (n = 4) of respondents preferred that the animal be captured and relocated to parks, while 87.5 % (n = 28) of respondents preferred the problem-causing animal to be destroyed. None of the respondents suggested monitoring as the best management option for this degree of threat. In conclusion, the research revealed that Human Animal Conservancy Self Insurance Scheme does not treat the cause of the problem but the symptom. This approach does not decrease the level of the problem given that the cause of the problem is not addressed. Therefore, the researcher stressed the need to fully explore and implement the recent piloted lion, crocodile fencing, and elephant proof fencing and elephants chilli coil to address and reduce the problem within Kwandu Conservancy. In addition, the research revealed that the scheme has very lengthy delays before compensation is paid and the review panel does not arrange meetings on the stipulated dates. This causes a back-log in the number of claims that need to be reviewed and approved. On Human Wildlife Conflict the research findings recommend the need to strengthen and improve existing problem-causing animal management strategies that are in place. Innovative strategies include reducing the number of stray livestock at night and developing static fences. Communities should be advised, as is being done by IRDNC, to herd their livestock during the day and to build strong kraals. This is the most effective and cheapest way to prevent livestock from being taken by predators at night. Further more the research revealed that the combination and rotation of the methods yield high success rather than deploying a single method over a long period, for the prevention of crop losses methods include guarding the crop field, cracking a whip, shooting in the air, watchtowers, human statues and beating drums.
Understanding environmental assessment and public participation process challenges among the vulnerable interested and affected parties : five cases studies from rural KwaZulu-Natal.
(2008) Mahlangu, Isaiah Mahlolani.; Dent, Mark Clifford.
The Public Participation Process (PPP) for Environmental Assessment (EA) is a mandatory procedure to facilitate participation of Interested and Affected Parties (IAAPs) in decision making for proposed development projects. Participation of the vulnerable IAAPs in the PPP is affected by complex challenges. These challenges make it difficult or impossible for Environmental Assessment Practitioners (EAPs) to successfully conduct and complete PPPs. This study investigated the nature and impact of the challenges in the decision making process. The study sought to develop an understanding of the challenges and suggest better approaches. Based on purposive sampling, a case study approach was adopted to analyse five PPP cases conducted in rural KwaZulu-Natal. Five key challenges: lack of EA legislation awareness; imbalanced power relations; negative past experience; threat to environmental autonomy; and poor project planning affected the PPP cases analysed in this study. These challenges emanate from internal and environmental factors. The study argues that internal challenges such as a lack of EA legislation awareness can be managed better during the PPPs. However, external challenges such as imbalanced power relations are usually impossible to resolve during the PPP. The modes of communication play a key role in public participation. Word of mouth is appropriate to facilitate participation of the vulnerable IAAPs. A key finding was the combined impact of the challenges and appropriateness of communication mode determines the PPP outcome, with the challenges being significant determining factor. The study maintains that a good understanding of potential challenges associated with development project sites will enable EAPs to design better and more responsive PPP approaches. To achieve this, the study recommends a Dual Approach Planning Model (DAPM). This approach recommends designing the PPP through preplanning information appraisal and prediction of potential challenges to create awareness about potential challenges. The DAPM argues that this awareness will assist EAPs to better estimate the time and to mobilise tools and resources required to manage the challenges, while focusing on successful completion of the PPP. This approach is also adaptive in nature.
Field spectroscopy of plant water content in Eucalyptus grandis forest stands in KwaZulu-Natal, South Africa
(2008) Oumar, Zakariyyaa.
The measurement of plant water content is essential to assess stress and disturbance in forest plantations. Traditional techniques to assess plant water content are costly, time consuming and spatially restrictive. Remote sensing techniques offer the alternative of a non destructive and instantaneous method of assessing plant water content over large spatial scales where ground measurements would be impossible on a regular basis. The aim of this research was to assess the relationship between plant water content and reflectance data in Eucalyptus grandis forest stands in KwaZulu-Natal, South Africa. Field reflectance and first derivative reflectance data were correlated with plant water content. The first derivative reflectance performed better than the field reflectance data in estimating plant water content with high correlations in the visible and mid-infrared portions of the electromagnetic spectrum. Several reflectance indices were also tested to evaluate their effectiveness in estimating plant water content and were compared to the red edge position. The red edge position calculated from the first derivative reflectance and from the linear four-point interpolation method performed better than all the water indices tested. It was therefore concluded that the red edge position can be used in association with other water indices as a stable spectral parameter to estimate plant water content on hyperspectral data. The South African satellite SumbandilaSat is due for launch in the near future and it is essential to test the utility of this satellite in estimating plant water content, a study which has not been done before. The field reflectance data from this study was resampled to the SumbandilaSat band settings and was put into a neural network to test its potential in estimating plant water content. The integrated approach involving neural networks and the resampled field spectral data successfully predicted plant water content with a correlation coefficient of 0.74 and a root mean square error (RMSE) of 1.41 on an independent test dataset outperforming the traditional multiple regression method of estimation. The potential of the SumbandilaSat wavebands to estimate plant water content was tested using a sensitivity analysis. The results from the sensitivity analysis indicated that the xanthophyll, blue and near infrared wavebands are the three most important wavebands used by the neural network in estimating plant water content. It was therefore concluded that these three bands of the SumbandilaSat are essential for plant water estimation. In general this study showed the potential of up-scaling field spectral data to the SumbandilaSat, the second South African satellite scheduled for launch in the near future.
Integrated use of yeast, hot water and potassium silicate treatments for the control of postharvest green mould of citrus and litchi.
(2010) Abraham, Abraha Okbasillasie.; Laing, Mark Delmege.; Bower, John Patrick.
There is a growing recognition globally that many agrochemicals are hazardous to humans, animals and the environment. Therefore, there is a need to substitute these chemical products with biological and physical treatments, and to change agronomic practices in order to control pests and diseases in agriculture. The primary objective of this thesis was to develop and test in laboratory, field and commercial packhouses trials as alternative control measures against green mould of citrus (caused by Penicillium digitatum Pers: Fr. Sacc) and Penicillium molds of litchi (caused by several Penicillium). A South African isolate of P. digitatum, isolated from an infected orange fruit, was found to be resistant to imazalil (the standard postharvest fungicide used in South Africa). Sixty yeast and 92 Bacillus strains were screened for their antagonistic activity against this isolate of P. digitatum. None of the yeasts or Bacillus isolates produced a curative action against P. digitatum on oranges. However, yeast Isolate B13 provided excellent preventative control of P. digitatum, superior to all the Bacillus isolates, when it was applied to citrus fruit prior to artificial inoculation with P. digitatum. Electron microscopy showed that yeast Isolate B13 inhibited conidial germination of P. digitatum. For the control of P. digitatum pre-harvest, trees were sprayed with a yeast, Isolate B13, a few months or a few days before harvest. However, this treatment alone proved to be ineffective in providing preventative control of green mould on Valencia oranges. For the control of P. digitatum preharvest, trees were treated with potassium silicate for a full season. Regular potassium silicate treatments resulted in a significant preventative control of P. digitatum infection on both navel and Valencia oranges. Treatment of Eureka lemons with potassium silicate as a postharvest treatment for the control of P. digitatum resulted in reduced disease lesion diameters when applied preventatively or curatively. Electron microscopy showed that potassium silicate inhibited germination of P. digitatum conidia and growth of its mycelium. Hot-water dip treatment at 50-58°C for 60-180 seconds (in increments of 15 seconds), significantly reduced infection development in inoculated wounds of Valencia oranges compared with control fruit treated with tap water, without causing any rind damage. The integration of the yeast, a hot water dip and potassium silicate pre-and postharvest applications provided control of P. digitatum control in multiple packhouse trials. The control achieved by the yeast Isolate B13 or hot-water, and potassium silicate in the packhouse alone was superior or equivalent to that provided by imazalil. A similar study was also carried out to determine possible control measures for Penicillium sp. on litchis. In this study, a total of 23 yeast and 13 Bacillus isolates were obtained from litchi fruit surfaces. Ten yeast and 10 Bacillus isolates that had shown good efficacy against P. digitatum of citrus were added to these for screening against Penicillium sp. of litchis. None of the yeasts or Bacillus isolates produced a curative action against Penicillium sp. infection on litchis. However, several yeast isolates (YL4, YL10, YLH and B13) resulted in reduced severity of the pathogen, when applied preventatively, compared with an untreated control. The yeast isolates were superior to all the Bacillus isolates, when applied to litchis prior to artificial inoculation by Penicillium infection on litchis. Potassium silicate as a postharvest treatment for the control of the pathogen caused reduced lesion diameters when applied preventatively or curatively to naturally infected litchis. The results presented in this thesis highlight the use of biological, physical and agronomic practices singly or in combination as an alternative control strategy against citrus postharvest green mould. This thesis also provides an insight into expanding these strategies, partly or fully, for the control of other postharvest Penicillium infections using litchi as an example.
Perceptions of the impacts of artificial flood releases on the general use of the natural resources of the Pongolo River floodplain, South Africa.
(2007) Salagae, Modukanele Alloycius.; Jaganyi, Joan Nyangasi Ukiru.
A social survey of the communities living adjacent to the Pongolo river floodplain was carried out, in order to understand the perceptions of the impact of artificial flood releases on the general use of natural resources of Pongolo floodplain in terms of: general resource use, stream flow, water quality and subsistence agriculture. The results show that floodplain communities perceive that the present artificial flood releases which are intended to maintain the environmental requirements of the floodplain are not meeting their needs nor the needs of the environment. Key perceptions on environmental impacts identified are: (i) reduction in water required to maintain floodplain resources, (ii) deterioration in water quality and (iii) decrease in available floodplain land and natural resources.
Development of high yielding pigeonpea (Cajanus cajan) germplasm with resistance to Fusarium wilt (Fusarium udum) in Malawi.
(2007) Changaya, Albert Gideon.
Pigeon pea [Cajanus cajan (L.) Millspaugh] is a very important grain legume crop for food, cash and firewood in Malawi. However, its production is affected by Fusarium wilt (Fusarium udum Butler), which causes up to 100% yield loss. The deployment of resistant varieties would be an economical way to manage the disease, and for this, more information is needed on farmers' preferences for local landraces, how farmers and consumers can be involved in developing new varieties resistant to wilt disease, and the genetics of inheritance of resistance. This information would be used to devise a breeding strategy. A participatory rural appraisal was used in the southern region of Malawi to identify pigeonpea production and marketing constraints. Results showed that Fusarium wilt was the most prevalent and destructive disease of pigeonpea in the area. Other constraints included pests, flower abortion, low yields, and low soil fertility. Local landraces accounted for 84% of the pigeonpea production in Malawi. Local landraces were preferred due to their fast cooking time, taste, and the high prices they earn the farmer. Participatory variety selection was used to identify landraces with desirable traits that could be used in the breeding programme. Farmers and buyers selected ten local landraces which were used in the genetic improvement programme. Pigeonpea local landraces and international Crops Research Institute for the Semi-Arid Tropics (ICRISAT) genotypes were evaluated for wilt resistance, yield, and secondary traits at three sites over three seasons. Most of the landraces were susceptible to wilt and late maturing. However, AP10, a local landrace, was high yielding and resistant to wilt and outperformed ICRISAT varieties. This local landrace showed promise for use as a source material for Fusarium wilt resistance in other locally adapted farmer-preferred varieties lacking resistance. The local landraces needed genetic improvement in wilt resistance, yield, early maturity, number of branches and seeds pod. Laboratory and screenhouse studies were performed to develop a new Fusarium wilt screening technique. Grains of finger millet, sorghum, and wheat were tested as media for multiplying F. udum isolates. Pathogenicity tests were done on Bunda College and Bvumbwe Research Station isolates. The Bunda isolate was then used in an infested-seed inoculation technique against eight differential cultivars. The results showed that finger millet, sorghum and wheat were equally effective for rapid multiplication of F. udum isolates. Wheat grain showed the best results for pathogen multiplication and inoculation, due to the large seed size for easy handling. The inoculation process involved placing infested wheat grain on bruised pigeonpea roots and transplanting into soil in pots. The infested seed inoculation technique, which is the first of its kind for pigeonpea, was effective in screening pigeonpea for wilt resistance. The selected landraces were crossed with wilt resistant testers in a 12 lines x 4 testers mating scheme, and 48 F1 crosses were generated. These F1 crosses were evaluated for wilt resistance, yield, and secondary traits. The variations among F1 crosses for wilt and secondary traits were due to additive gene action in both parents and the dominance effects arising from the interactions of parents. Parental lines, with good combining ability effects for wilt resistance (AP2, AP3, and AP4), days to 50% flowering, seed pod, plant height, stem diameter, and number of primary and secondary branches were identified, while ICEAP00554 (tester) was a good general combiner for wilt resistance and days to 50% flowering. These lines would be useful in breeding for Fusarium wilt resistance in farmer-preferred pigeonpea genotypes in Malawi or similar environments. Specific F1 crosses were identified with significant SCAs for wilt resistance, days to 50% flowering, and secondary branches. The significance of GCA and SCA effects, which indicated importance of both additive and non-additive gene effects, respectively, suggested that both selection and hybridisation would be useful to improve the resistance in farmer-preferred varieties. Segregation analyses were conducted on F2 populations to determine the resistance to susceptibility phenotypic ratios. The Chi-square analyses showed that resistance to wilt was dominant over susceptibility in most F2 populations. The segregation ratios of 3:1, 13:3, 15:1, and 9:7 (R:S) indicated that either one dominant gene, or two inhibitory genes, or two independent dominant genes, or two complementary genes, respectively, were conferring wilt resistance in these crosses. Involvement of only a few genes governing wilt resistance suggested few complications, if any, in breeding for this trait in these locally adapted pigeonpeas. The Pedigree breeding method would be recommended for incorporating these traits.
The contribution of natural resource-based enterprise income to rural livelihoods : a case study of Ikhowe Craft enterprise in Eshowe, South Africa.
(2008) Mofokeng, Jafta Lehlohonogo.; Hay, Duncan.; Fincham, Robert John.
Many believe that small and medium natural resource-based enterprises (NRBEs) provide a vision to reduce poverty in the Third World’s rural communities and households. As a result, new rural enterprises should be created and existing ones reinforced within a framework of sustainable livelihoods that target all appropriate members in the communities. This study investigates the impact of the natural resource based enterprises income on the rural livelihoods in the households using a rural natural-based craft enterprise (using reeds, Cyperus spp, as raw material), as a case study, Ikhowe Craft Enterprise, situated in small town called Eshowe in northern KwaZulu-Natal, South Africa.. In designing this study, a combination of both qualitative and quantitative research methods was employed. This was influenced by the aim and the type of data required for the study. The said methods were (a) semi-structured interviews for producers (a questionnaire had a pre-determined mix set of both open-ended and closed-ended questions); (b) interviews for management were conducted with a purely qualitative questionnaire which consisted of only structured and open-ended questions; (c) field observations, and (d) a review of secondary materials (administrative records). Apart from how derived income impacts on the participants, data required also included performance of the enterprise, access to markets, support available, and livelihood analysis of the participants households which included issues such as households’ economies and exploring extent of, and reasons for diversification, and challenges both the enterprise and participants’ households face daily in relation to making a living. The results show that there was a significant increase in business annual turnover and producers’ earnings between 2003 and 2005. In 2003, about 50% of the producers earned less than R1000 per year, while in 2005 only 3% earned less than R1000 per year. Despite the total annual increase of earnings and the significant contribution of craft income to producers’ households’ incomes, individual earnings varied considerably amongst the producers and as a result the economic impact was also variable. Other than craft, strategies such as government grants enhanced livelihood diversification in the case study. However, lack of understanding of basic business principles and skills amongst both the crafters and management posed threats to the sustainability of the enterprise. The income derived from the NRBE activity, especially since it is based on natural resources with low economic value (reeds) was found to have both diversifying and supplementing effects on different producers’ other strategies. Although, the enterprise is achieving growth, there is a concern and a need to measure the future sustainability of the enterprise. In addition there is a need to improve the producers’ basic business skills and business management competency

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