Natural and Agricultural Sciences

Permanent URI for this community

http://hdl.handle.net/11660/5

Browse

Now showing 1 - 20 of 1807

Open Access
3D visualization of data from groundwater flow and transport models
(University of the Free State, 2000-11) Bekker, Meintjes; Messerschmidt, H. J.; Chiang, W. H.
English: Groundwater flow and transport models produce large amounts of data, which the human brain cannot possibly grasp. Taking advantage of the natural abilities of the human vision system, 3D visualization is often the tool of choice for understanding and communicating conceptual models, verifying model input, understanding model output, explaining and communicating conclusions and recommendations, and motivating expenses. A 3D visualization tool has therefore been developed for intelligence amplification of model data. The tool is based on a groundwater modeling system (Processing MODFLOW) and makes use of the results from existing groundwater flow (MODFLOW) and transport models (MT3DMS, PHT3D and RT3D.). The Visualization Toolkit (vtk), a C++ class library for visualization was used to render 3D geohydrological objects. Realistic scenes of 3D geospatial models and 3D distributions of geohydrological properties, such as hydraulic conductivity, heads and solute concentrations, can be rendered. The advantages of 3D visualization are evident by applying the visualization tool to case studies.
Open Access
A taxonomic study of the genus cryptolepis (periplocoideae: apocynaceae)
(University of the Free State, 2013) Joubert, Lize; Venter, A. M.; Venter, H. J. T.; Bruyns, P. V.
Cryptolepis R.Br. (Apocynaceae, Periplocoideae) was taxonomically revised. Detailed descriptions of macro and micro-morphology, palynology, geographic distribution and ecological characteristics were presented. An identification key to the species was compiled and the nomenclature of all species was revised while all available type material was studied and lectotypes and neotypes were designated where necessary. Molecular phylogenetic analyses, based on the gene regions ITS, trnD–T and trnT–F, of representative species of 28 periplocoid genera and 22 Cryptolepis species were presented and the monophyly of Cryptolepis was evaluated. Historically a total of 81 species names and four subspecies names were published for Cryptolepis. However, a large number of species names were later placed in synonymy or transferred to other genera, while several new combinations were published. This resulted in a total of 29 accepted Cryptolepis species at the commencement of this study. Three new species, C. ibayana, C. thulinii and C. villosa, resulted from this study and the latter two were described in this thesis. One species, C. producta, was synonymised with C. oblongifolia. Cryptolepis, therefore, comprises a total of 31 species at present. In terms of species diversity, distribution and potential pharmaceutical and economic value, Cryptolepis is one of the most significant genera in the Periplocoideae. Cryptolepis grows throughout sub-Saharan Africa, the southern parts of Yemen, the island archipelago of Socotra, and southern Asia ranging from India to southern China, Taiwan, the Philippines and Indonesia. Most of the species grow in tropical forests or savannah, but 13 species are also adapted to arid environments. The majority of Cryptolepis species are concentrated in four centres of diversity along the east coast of Africa and on Socotra. These hotspots are associated with both arid and forest refugia in areas which have been regarded as local centres of endemism for a number of other plant taxa. The phylogenetic analysis of Cryptolepis indicates that most of these hotspots were colonized repeatedly by different Cryptolepis groups. In addition to the influence of climate shifts, edaphic conditions and also fire had a significant influence on species diversity and distribution in Cryptolepis. Macro and micro-morphological investigations indicated that numerous characters, including growth form, leaf shape and size, leaf epidermal characters, venation, inflorescence structure, floral structure and seed coat surface characters, are of diagnostic value at species level in Cryptolepis. However, the species can only be accurately identified by using a combination of these characters. The molecular phylogenetic analyses revealed that Cryptolepis is paraphyletic and, in order to establish a monophyletic genus, it was proposed that the circumscription of the genus be broadened to include Parquetina as a synonym of Cryptolepis. Several vegetative and reproductive characters showed a high degree of homoplasy, suggesting a high degree of morphological plasticity. This plasticity was also found at species level in C. oblongifolia, which showed significant variation in vegetative and reproductive features. This, together with a high tolerance for disturbance, has resulted in C. oblongifolia becoming the most widely distributed of all Cryptolepis species.
Open Access
The ability of a novel compound to enhance the effect of urea on nitrogen deficient tomatoes
(University of the Free State, 2012-03-22) Pretorius, Hendri; Potgieter, G. P.
English: A company, Elementol (Pty) Ltd, requested the evaluation of their novel product, Pheroids. Pheroids can apparently facilitate the transport of phytological beneficial substances over membranes. Information regarding the chemical attributes was withheld as patent registration is still pending. Pheroids is apparently a microemulsion containing free fatty acids (FFA’s) and or fatty acid derivatives. It apparently encapsulates a substance and facilitates its transport over the membrane. The exact mechanism involving encapsulation, transport and release of the substances inside the cells is still vague due to little information available on it. The aim of this study was to evaluate the ability of Pheroids to facilitate the transport of additional nitrogen, urea in this case, in tomatoes grown under nitrogen limiting conditions. Tomatoes (Lycopersicon esculentum cv. Rodade Star) were cultivated in a greenhouse using a circulating ebb and flow hydroponic setup, which supplied the plants with either a control- or nitrogen limiting nutrient solutions. The plants cultivated in the nitrogen limiting conditions showed a remarkable reduction in vegetative development and yield. To alleviate the effect of nitrogen limiting conditions on yield, the plants were foliarly sprayed with 0.5% and 1% urea solutions, singly or mixed with Pheroids, once every two weeks. The purpose of these foliar treatments was to determine whether Pheroids can further enhance the absorption and transport of urea across membranes of the leaves to alleviate the effect of limiting nitrogen supply. Plants grown under nitrogen adequate conditions (control) were also foliarly treated with a 0.5% urea solution, singly and mixed with Pheroids, to determine to which extent control plants react to the additional nitrogen supplied. The reduction in yield, as a result of limited nitrogen supply, was partially alleviated by spraying nitrogen deficient plants with the 0.5% and 1% urea solutions. However, mixing the 0.5% and 1% urea solutions with Pheroids, not only improved vegetative growth and generative development, but also improved yield, suggesting that Pheroids indeed has the ability to improve the uptake of urea. The 0.5% urea / Pheroids solution specifically proved to have the best ability in alleviating the effect of nitrogen limiting conditions on yield without compromising fruit quality. Although the reducing effect was not completely alleviated, the yield and loss in income as a result of nitrogen limiting conditions was prevented to a large extent. Spraying control plants with 0.5% urea, singly or mixed with Pheroids, also improved yield, without compromising fruit quality. In addition, Pheroids itself, without mixing it with any substance, also resulted in increased yields in both control- and plants grown under nitrogen limiting conditions. In summary, it appeared that Pheroids has the ability to facilitate the transport of phytological beneficial substances, in this case urea, over plant membranes and enhances cellular nitrogen content, but this needs further detailed analyses. This phenomenon was more evident in plants grown under nitrogen limiting conditions than in plants grown under control conditions. Taking into consideration that most crops frequently may suffer from nitrogen limiting conditions in standard agricultural practices, Pheroids may have numerous potential applications in the agricultural industry.
Open Access
Abiotic stress tolerance and nutritional traits of newly developed quality protein maize hybrids in sub-Saharan Africa
(University of the Free State, 2022) Engida, Bitew Tilahun; Labuschagne, M. T.; Terekegn, A.; Van Biljon, A.; Wegary, D.
Drought and poor soil fertility are some of the most serious maize production challenges in sub-Saharan Africa (SSA). Identification and development of quality protein maize (QPM) cultivars that have high yield potential and tolerance to these stresses is a reliable and affordable option to improve food security and malnutrition problems in the region, especially for small scale farming communities. Although several stress tolerant maize varieties have been released and disseminated for commercial production in SSA so far, limited development and release of stress tolerant and high yielding QPM varieties compared to normal maize varieties is evident. Limited attention has also been given to the development of nutritionally enriched varieties compared to grain yield improvement. Therefore, the main goal of this study was to study 40 newly developed QPM hybrids obtained from the International Maize and Wheat Improvement Center (CIMMYT) – Zimbabwe, under stressed and non-stressed environments to allow selection of QPM hybrids that could outperform the existing commercial QPM and normal maize cultivars with respect to grain yield and concentrations of tryptophan, iron (Fe), zinc (Zn) and molar ratios of Fe and Zn to phytic acid. The specific objectives were: (1) to determine variability and performance of QPM hybrids for grain yield and agronomic traits under stressed and non-stressed environments, (2) to determine tryptophan, Zn and Fe concentrations, and molar ratios of Zn and Fe to phytic acid in QPM hybrids grown under stressed and non-stressed environments, (3) to analyse genotype by environment interaction and grain yield stability of QPM hybrids and (4) to determine correlations among grain yield, agronomic and nutritional traits in QPM hybrids evaluated under stressed and non-stressed environments. Significant variation was seen for grain yield, and almost all studied agronomic and nutritional traits under stressed and non-stressed environments. Phenotypic coefficient of variation (PCV) was higher than genotypic coefficient of variation (GCV) for grain yield and all other agronomic and nutritional traits under all conditions, indicating that environment effect was higher than genotype effect on the expression of the traits under stressed and non-stressed environments. Broad sense heritability of grain yield was higher than 0.6 across all environments, with the exception of managed drought conditions. Anthesis silking interval (ASI) had relatively high GCV estimates and genetic advance, as a percentage of the mean, across all conditions. This indicated that the presence of sufficient genetic variability among genotypes can improve synchronization under different management conditions through selection. Grain yield was reduced by 47% under random stress, 68% under managed drought and 71% under low N conditions. Protein and tryptophan concentrations in the grain were decreased by 36.0% and 21% respectively under low N conditions and Fe and Zn concentration also decreased by 48% and 36% under low N stress and 63% and 9% under random stress, respectively. Some QPM hybrids showed better or comparable performance in terms of grain yield potential and nutritional quality traits compared with the best QPM and normal maize checks under different management conditions, indicating the genetic gain that has been made in the QPM breeding programme. Based on Additive Main effect and Multiplicative Interaction (AMMI) analysis and Genotype and Genotype by Environment interaction (GGE) biplot analysis entries 10 (CZH142238Q) and 14 (CZH15142Q) under optimum; 23 (CZH17192Q) under random stress; 19 (CZH17188Q) and 40 (CZH17209Q) under managed drought and 14 (CZH15142Q) under low N were the most stable and the highest yielding hybrids. Environments Kwekwe (KW), Bindura (BIN), Chokwe (CHO) and Bako (BK2) were identified as discriminating and representative sites for optimum conditions, random stress, managed drought and low N stress conditions, respectively, therefore these environments are promising for selecting well adapted genotypes in the respective management conditions. Grain yield was significant and positive correlated with number of ears per plant and negatively with days to anthesis and silking under low N stress. This confirmed the importance of these secondary traits in developing high yielding and early maturing genotypes. Grain yield was not significantly correlated with most of the nutritional quality traits under all management conditions, indicating a lack of common genes for simultaneous improvement of grain yield and these nutritional traits. Significant and positive correlations were observed between Fe and Zn under low N and random stress conditions.
Open Access
The acceptability of earth constructed houses in central areas of South Africa
(University of the Free State, 2015) Bosman, Gerhard; Steÿn, Das; Van der Westhuizen, Diaan; Atkinson, Doreen
English: The traditional earth building techniques of South Africans are well documented, but little research reflects the current perceptions of these building materials and techniques. The thesis explores the factors (independent variables) that can be addressed in order to make earth constructed houses in general more acceptable in central areas of South Africa. The thesis draws on data obtained from the SANPAD project (South Africa-Netherlands Research Programme on Alternatives in Development) with a household survey (n=1790) from respondents regarding their perceptions and attitudes towards earth construction. Multiple qualitative and quantitative responses were recorded both for and against the use of sun dried earth blocks (adobe). Correlation and regression analyses were used to test for the characteristics (significant variables) that influence the acceptability of earth constructed houses. The findings show that respondents regard traditional earth building materials as inferior. Negative attitudes were found to be linked to the structural performance of unbaked earth materials regarding stability in wet conditions and maintenance. Limited other studies confirmed the low acceptability of traditional earth constructed walls. Regression analysis could not confirm that personal and household characteristics are associated with the housing, context and acceptability characteristics. Correlation analyses confirmed that certain housing characteristics (basic services such as water born toilets connected to sewerage systems, running water and electricity) influence the acceptability of traditional earth constructed houses. Correlation analyses confirmed that context characteristics (location and area types) influence the acceptability of traditional earth constructed houses. Furthermore, the data and literature confirm that the building culture (available material and buildings skills) and upward social mobility together with Reconstruction and Development Programme (RDP) houses (with basic services) influence the acceptability of traditional earth constructed housing. The findings concluded that attitudes toward traditional earth construction are more positive in 1) informal urban areas where informal houses do not have access to basic services and 2) rural households where the building culture dictates the norm even without basic services. The effects of conformity, imitation and upward social mobility were confirmed, as stated by the literature and the data. Together with upgraded earth construction techniques (such as cement stabilised compressed earth blocks or bricks) wall components for earth buildings in parts of central South Africa may be more acceptable. The hypothesis is that if the influencing factors on the acceptability of traditional earth constructed housing are known, it can be used in the promotion of contemporary earth construction. The thesis aims to promote contemporary earth construction techniques. This thesis states that the public should be equipped and educated about the importance of preserving existing forms and methods of earth construction, in order to support useful applications within contemporary architecture.
Open Access
Access to credit and agricultural production in Lesotho
(University of the Free State, 2012-01) Motsoari, Charmaine; Van Schalkwyk, H. D.; Cloete, P. C.
English: One of the factors hindering development in Lesotho is the limited access to credit. The development of the rural economy in developing countries depends on growth and development in the agricultural sector and other small and medium enterprises. These enterprises constitute the engine of growth, employment and income for the rural community. In an effort to make the landscape of rural finance more attractive and to fulfil the national objectives of increased production, policy makers and donors adopted the conventional approach of advancing credit, where all practices and operational procedures were geared towards the interests of the borrower. The initiatives to advance credit include amongst others, an emphasis on project appraisals, relaxing collateral requirements and the charging of close to market interest rates. Despite the changes, the problem of limited access to financial services still exists. In fact, these approaches (policies) invariably resulted in distortions in the financial markets, and reduced the number of financial products and services to which farmers have access. The purpose of this study therefore, was to examine factors that influence small-scale farmers’ access to credit, thereby affecting their productivity and to make suggestions for government interventions and for the reduction of market failures in the rural financial markets of Lesotho. The study was conducted in two agro-ecological zones in Lesotho, namely; the Lowlands and the Highlands regions. A random sample of districts in the regions was done to select representative districts in each region. Leribe, Mafeteng, and Berea districts represented the Lowlands while Mohale’s Hoek and Thaba-Tseka districts represented the Highlands region. Stratified random sampling was employed to select borrowers and non-borrowers for the study. The study employed the logistic regression model (logit) within the principal component regression (PCR) framework to assess factors affecting small-scale farmers’ access to credit. PCR was used to take care of the multicollinearity between the variables. Firstly, the variables included in the logit model were subjected to principal component analysis (PCA) in order to reduce the variables into a few uncorrelated principal components (PCs). After principal components (PCs) were calculated, PCs with the smallest eigenvalues were eliminated and then PCR was fitted using standardised variables to improve the estimation power of the logit model. The empirical evidence of the study indicates that non-farm income, savings and remittances and pensions confirmed that increasing the household’s total income reduces the probability of a household being credit constrained. This shows that a better household situation affects the decision of the lender to ration the loan or that the household has less demand for loans because of its own equity capital accumulated through past income earnings. Farm income on the other hand, is positive, confirming that a higher farm income may improve the farmer’s creditworthiness and in some cases create a demand to expand production, thus increasing the demand for credit. The study revealed that farm income values of borrowers are higher than those of nonborrowers but lack of baseline data makes it difficult to associate the differences to the loans obtained by borrowers. However, the changes in income among borrowers are linked to the use of credit, confirming the hypothesis that credit has a positive effect on income and improvement of living conditions of credit users. Research into the behaviour of credit institutions in Lesotho will help to explain some of the actions taken by credit institutions, and at the same time assist policy-makers in formulating appropriate interventions.
Open Access
Acid-base potential characterisation in the Southern highveld coalfield of Mpumalanga
(University of the Free State, 2017-07) Ntwaeaborwa, Gaonkile Molly; Deysel, Lore-Mari
Pyrite, iron disulphide is the most common mineral in the metal sulphite and coal deposit. The oxidation of Pyrite and other metal-sulphide minerals by oxygen has a large environmental impact and plays a key role in Acid Mine Drainage (AMD). Environmental impact shows that soil acidity, toxic metal concentrations and vegetation damage are the predominant negative impact of AMD. AMD is a major concern for the mining industry because mining activities tend to increase the amount of rock surface exposed to air and water. Mining companies are increasingly required to evaluate the AMD potential at future mine sites and provide detailed plans to prevent or minimise AMD at all phases of mine operation as part of the environmental Impact assessment (EIA) process. An investigation was conducted in two mine (Mine 1 and Mine 2) areas in the Southern Highveld Coalfield of Mpumalanga. Mine 1 is an underground coal mine and is situated 10 km outside Trichardt on the road to Bethel. It was established in May 2012 and its shaft supply coal to Sasol Synfuels. Mine 2 is an open-cast coal mine and is situated between 2 towns, amely Trichardt and Kriel. Construction activities started in 1990 and the mine reached full production in September 1992. Both Mines fall in the Karoo Supergroup which comprises of Ecca group formation and consist dominantly of sandstone, siltstone, shale and coal. The aim of this study was to investigate the acid-base potential of these two Mines. 118 samples were collected from Mine 1 borehole core and 71 samples were collected from Mine 2 borehole core to conduct mineralogical and Acid Base Accounting (ABA) analysis. Acid- base potential leachate were further analysed for major and trace elements using Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). Most of the samples analysed for Mine 1 have been found to have High AMD risk at the interburden and these samples have low NNP values, all these samples consisted of coal and they contained pyrite mineral as indicated in the mineralogical analysis. These samples must be taken into consideration to minimise oxidation. Samples (Mine 1) that contained layers of sandstone, siltstone and shale have the highest NNP values and these layers can be used as a buffer to neutralise the AMD. Therefore Mine 1 will produce an AMD at the coal seam once exposed during mining. Mine 2 shows that 3 samples have High AMD risk at the interburden while 2 boreholes show the risk between 20m and 60m, and these samples were coal samples and others were sandstone samples and they contained pyrite. These samples that have coal showed low NNP. Therefore most of the acid generation would be mainly found at the coal seams. Layers that show high NNP values consisted of sandstone, siltstone and shale. They showed no indication of acid generation, therefore they will work as buffers to neutralise the any AMD that will be produced. Mine 2 also indicate that AMD will be produced at the interburden at layers that contains coal, therefore more consideration is needed when these layers are exposed during mining. With such condition it is possible for the mines to predict the types of situations that might arise concerning groundwater quality, and implement proper prevention or remediation programs.
Open Access
Activity patterns of birds in the central Free State, South Africa
(University of the Free State, 2009-11) Van Niekerk, Daniël Johan; Kok, O. B.
Activity patterns of bird species were studied at Glen Agricultural College within the grassland area of the central Free State, South Africa, during a period of 11 years (July 1997 - July 2008). The study focused on a specific grassland locality where 5-minute checklists were compiled continuously from dawn to dusk at least once a week for a total of 656 days. Data were also collected each minute for selected species. Additional observations in an adjacent tree and shrub dominated drainage line included I-minute checklists compiled during transects over a two-year period (late autumn 2000/1 to mid-autumn 2002/3) as well as surveys from a fixed position from dawn to approximately 70 minutes after sunrise during 2007/8. The central aim of the study was to quantify and explain annual, seasonal and daily activity patterns of all bird species recorded in the study area. This data is summarised in separate species accounts where aspects of the annual cycle, particularly breeding and moulting, were also considered. In addition, the potential influence of rainfall was investigated. The study reveals, for the first time, how the activity patterns of a southern African bird community change through time, and how the amount and timing of rainfall can influence these patterns. In spite of similarities amongst species when daily, seasonal and annual patterns are considered separately, the study also shows that each species is unique when all its data is considered simultaneously. Because activity patterns can have a substantial influence on the detectability of a species, the accuracy and usefulness of surveys aimed at estimating bird numbers is consequently questioned. The study at Glen also shows how activity patterns can be used to help unravel the annual cycle of species in a time and cost effective way.
Open Access
Actuarial risk management of investment guarantees in life insurance
(University of the Free State, 2010-11) Bekker, Kobus Nel; Dhaene, Jan; Finkelstein, Maxim
Investment guarantees in life insurance business have generated a lot of research in recent years due to the earlier mispricing of such products. These guarantees generally take the form of exotic options and are therefore difficult to price analytically, even in a simplified setting. A possible solution to the risk management problem of investment guarantees contingent on death and survival is proposed through the use of a conditional lower bound approximation of the corresponding embedded option value. The derivation of the conditional lower bound approximation is outlined in the case of regular premiums with asset-based charges and the implementation is illustrated in a Black-Scheles-Merton setting. The derived conditional lower bound approximation also facilitates verifying economic scenario generator based pricing and valuation, as well as sensitivity measures for hedging solutions.
Open Access
Adaptation to climate change and impact on smallholder farmers' food security in South Africa
(MDPI, 2022) Ogundeji, Abiodun A.
If not adequately managed, climate change is predicted to have a large negative impact on smallholder subsistence farmers, posing a significant danger to household food security. However, the role of adaptive techniques used by farming households to reduce these negative effects and, as a result, their food insecurity status has not been sufficiently evaluated. This study explores the factors that influence smallholder farmers’ adoption of climate change adaptation measures, as well as their impact on household food security. Using an endogenous treatment-effect ordered probit model, agricultural households’ food security status is likely to significantly improve when they employ measures to adapt to adverse climatic conditions. The empirical findings also show that the gender makeup of the household, age, tropical livestock unit, and access to climatic information improve the likelihood of smallholder farmers adopting climate change adaptation measures. Based on the findings, this study advocates that governments and non-governmental organizations (NGOs) support smallholder farmers’ Indigenous adaptation options with various institutional, regulatory, and technological assistance, with a particular emphasis on female-headed households.
Open Access
Adaptation, coping strategies and resilience of agricultural drought in South Africa: implication for the sustainability of livestock sector
(Elsevier Ltd., 2021) Bahta, Yonas T.; Myeki, Vuyiseka A.
Agricultural drought has put sub-Saharan African under significant pressure, and without adaptation, will negatively influence a future generation. Hence, it is crucial to assess the adaptation and coping strategies, the resilience of agricultural drought, its implication on the sustainability of the livestock sector, and developing future interventions. Data of 217 smallholder livestock farmers were used in a principal component analysis to estimate the agricultural drought resilience index as an outcome variable against social wellbeing, economic outcome, environmental variable and adaptive capacity variables. The results found that 21% of the livestock farming households sold their livestock as an adaptation and coping strategy. In contrast, 20% of the farming households used alternative land use as an adaptation, and coping strategy, 20% stored food, 17% asked for animal feed, 6% sought employment, 6% migrated, 5% kept drought-tolerant breeds, 3% received relief grants, 2% used their savings and investments, and 1% leased their farms. When natural, economic and social sustainability was viewed as a resilience process, the three pillars positively and significantly impacted households' agricultural drought resilience. This implied that the more smallholder farmers participated in social networks and cooperatives, the higher the resilience to agricultural drought. Further, the more resources, income, access to land, access to water, access to credit, and additional types of farming, the higher the households’ resilience to agricultural drought and adaptive capacity. Thus, the three pillars of sustainability are crucial for enhancing the resilience and adaptability of smallholder livestock farmers. The study recommends that government aid reduce vulnerability to agricultural drought via access to agricultural credit and encourage farmers to be part of social networks and cooperatives. Additionally, the government could improve access to land and water rights to boost the resilience of smallholder farmers to agricultural drought. This could be achieved through collaboration and coordination among all role players.
Open Access
Adaptive dynamics for an age-structured population model with a Shepherd recruitment function
(University of the Free State, 2013-06-07) Ellis, Michelle Heidi; Schoombie, S. W.
English: In this study the evolution of the genetic composition of certain species will be replaced by the evolution of the traits that represent these genetic compositions. Depending on the nature of the trait of interest, a scalar valued parameter called the strategy parameter will be assigned to this trait making the simulation of strategy evolution possible. The trait of interest, and therefore the strategy associated, will be the ability of a population to keep its densities within the carrying capacity of the environment they find themselves in. The Shepherd function, on account of its wide use in population simulations as well as composing of exactly such a density parameter, will be the density curbing mechanism of choice in the age-structured population model designed here. An algorithm will be designed to simulate strategy evolution towards an evolutionary stable strategy or ESS that will ensure not only an optimal fit for this environment but also render the population immune against future invasion by other members of the population practising slight variations of this strategy. There are two ways to come by such an optimal strategy without directly involving genetics. The first is game theory, allowing strategists to compete for this position, and the second is with the use of adaptive dynamics, converting winning and loosing instead into tangible mathematics. Combining these two classics will show that the quest is an exercise in strategy optimization, not only from the point of view of an already established population but also from the point of view of an initially small one. It will be interesting!
Open Access
ADH2 regulation in the yeast Saccharomyces cerevisiae
(University of the Free State, 2004-05) Khoboko, Mojabatho Portia; Albertyn, J.; Du Preez, J. C.
English: The aim of this study was to investigate the ability of ethanol to repress the expression of ADH2 in the genome of Saccharomyces cerevisiae. To achieve this, an expression cassette (ADH2::LacZ) using LacZ as a reporter gene was constructed using the YIp356R shuttle vector. A 1000 bp up and downstream region, flanking the open reading frame of ADH2, was fused to the 5’-end and 3’-end of the LacZ gene in the YIp356R shuttle vector. Numerous attempts were made to transform the expression cassette (ADH2::LacZ) into S. cerevisiae (strain W303) containing a deleted ADH2 (adh2Δ::URA3), to displace the deletion cassette through homologous recombination, thereby placing ADH2::LacZ in the place of the ADH2 in genome of S. cerevisiae. This was unfortunately not successful and it was decided to use an alternative approach. In this case the expression cassette was cloned into the integrative vector YIplac211 and transformed into S. cerevisiae. For initial confirmation, the yeast transformants were grown on selective plates containing X-gal, which allows for the detection of β-galactosidase activity through the production of blue coloured colonies. The detection of the blue colour confirmed that the expression cassette was successfully constructed and integrated into the genome. Two randomly selected transformants were cultivated on 20 g glucose l-1 as sole carbon source, to study glucose repression and on three different ethanol concentrations to study the effect of ethanol on the expression of ADH2. Selection was maintained by growing the yeast in a URA– chemically defined media (pH 5.5) at 30ºC. Samples were taken at appropriate intervals to perform β-galactosidase assay, assess utilization of substrate (ethanol and glucose), ethanol formation and biomass determination. During growth on 20 g glucose l-1 the production of β-galactosidase was apparent only when glucose concentrations were very low (2.3 g l-1), indicating that glucose levels have to decrease to a critical level before ADH2 expression can resume. The highest final biomass was produced during growth on 20 g glucose l-1. During growth on the three different ethanol concentrations the highest β-galactosidase maximum specific activity was obtained during growth on 20 g ethanol l-1 (3 643 U mg-1) and the lowest during growth on 5 g ethanol l-1 (2 533 U mg-1). Although the maximum specific activity obtained during growth on 30 g ethanol l-1 were higher than that obtained during growth on 5 g l-1, the production rate was the lowest (93 U mg-1h-1) during growth on 30 g ethanol l-1, suggesting that 30 g ethanol l-1 concentration has negative effect on the expression of ADH2. However this slow production might have been due to the slow growth during this cultivation and not due to ethanol repression. The possible repression of ADH2 is further disputed by the high β-galactosidase production on 30 g ethanol l-1.
Open Access
Adult-plant resistance to Puccinia recondita f. sp. tritici in a collection of wild Triticum species
(University of the Free State, 1999-05) Barnard, Johanna Elizabeth; Pretorius, Z. A.; Kloppers, F. J.
English: The ability of rust pathogens to mutate and form new and virulent races, necessitates the broadening of the genetic base of resistance in common wheat to rust diseases. The wild relatives offer a rich reservoir of resistance genes. In an attempt to identify new sources of resistance to Puccinia recondita f. sp. tritici, 353 Triticum accessions, comprising diploid, tetraploid and hexaploid species were evaluated for seedling and adult-plant resistance to a mixture of pathotypes UVPrt2, 3, 9, and 13. In addition to infection type studies, plant height, growth habit and head type of adult plants were also recorded. One hundred and twenty six of the accessions were resistant to moderately resistant as seedlings to the pathotype mixture, whereas 180 were resistant or moderately resistant as adult plants. The number of days from planting to flag leaf stage varied from 54 to 187. High levels of resistance were observed in adult plants of T. longissimum, T. sharonense, T. searsii and T. turgidum ssp. compactum. Triticum kotschyi and T. ventricosum expressed hypersensitive infection types. Partial resistance (small pustules without any apparent chlorosis), was observed in T. turgidum ssp. durum, T. turgidum ssp. pyramidale and T. tauschii. In T. turgidum, which comprised 14 subspecies and 272 accessions, approximately 44% of the adult plants were resistant to moderately resistant compared to 24% of the seedlings. According to these results 13 accessions, producing smaller or fewer leaf rust pustules, without the characteristic chlorosis and necrosis associated with hypersensitive resistance, were selected. Adult plants were quantitatively inoculated with pathotype UVPrt13 of P. recondita f. sp. tritici. Palmiet, a bread wheat cultivar susceptible to UVPrt13, was included as a control. Latent period of leaf rust, uredium size and density, and infection type were determined in two experiments. In the first experiment latent period ranged from 309 h to 401 h compared to 258 h in the susceptible control, Palmiet. In the second experiment Palmiet had a latent period of 244 h whereas those in the Triticum accessions ranged between 175 hand 372 h. Most accessions supported more uredia per ern" flag leaf surface than Palmiet in the first, but not in the second experiment. However, pustules were significantly smaller on most of the lines. Based on these components, T. timopheevii ssp. araraticum v. tumanianii, T. turgidum ssp. durum v. obscurum, and T. turgidum ssp. persicum v. stramineum, showed high levels of partial resistance. Triticum turgidum and T. timopheevii accessions rated as potentially valuable sources of resistance were selected for histological studies on mechanisms of resistance. Penetration and establishment of the leaf rust pathogen were studied in flag leaves of T. timopheevii, T. turgidum ssp. dicoccum, T. turgidum ssp. durum and T. turgidum ssp. compactum. The T. aestivum wheats Thatcher (Tc) (susceptible common wheat control) and TcLr19 (resistant common wheat control) were included in the experiment. Using fluorescence microscopy, infection sites of pathotype UVPrt13 were examined for the percentage prestomatal exclusion (germtubes not forming appressoria and appressoria not forming over stomata), abortive penetration (non penetrating appressoria and aborted substomatal vesicles), early abortion (six or less haustorium mother cells per infection site) and infection sites successfully culminating in colonies. Flag leaf sections were prepared for phase-contrast microscopy by staining with either Trypan blue alone or in combination with a solution of picric acid in methyl salicylate. To confirm and expand light microscopy observations, upper and inner surfaces of epidermal tissue of T. timopheevii and T. turgidum ssp. dicoccum were fixed and prepared for scanning electron microscopy. Observations showed that resistance in T. timopheevii was typically hypersensitive and may thus not be durable. The prehaustorial resistance exhibited in T. turgidum ssp. durum and T. turgidum ssp. compactum, may be valuable sources of nonhypersensitive resistance when transferred to cultivated wheat.
Open Access
Advances in the systematics and ecology of African Corinnidae spiders (Arachnida: Araneae), with emphasis on the Castianeirinae
(University of the Free State, 2012-01) Haddad, Charles Richard; vdM Louw, Schalk; Dippenaar-Schoeman, Ansie
English: The Corinnidae is one of 76 families of spiders (Arachnida: Araneae) presently recognised in the Afrotropical Region. By the end of the last century their taxonomy and systematics had been very poorly studied and no modern revisions existed on the group. At that time, 110 species in 22 genera were known from the region, making it a family with moderate species richness. The description of the new genus Hortipes Bosselaers & Ledoux, 1998 in the family Liocranidae signalled the start of modern systematics studies in that family, and following the transfer of Hortipes to the Corinnidae, of that family by default too. Since that time, 20 taxonomic papers have been published on the Afrotropical Corinnidae and 10 new genera (all endemic to the region) and 164 new species have been described, of which three species form part of the current study (Chapters 7 and 9). Several genera have also been transferred to or from the Corinnidae in those papers. Presently there are 35 genera and more than 270 species known from the region, with the Corinnidae now ranking eighth in species richness in the region. Most of the revisionary work so far has focused on the subfamilies Trachelinae and Phrurolithinae, while the Corinninae sensu lato and Castianeirinae have largely remained neglected. The broad aim of the current study was to focus on the systematics of the latter group, treat the taxonomy of each of the currently known genera, at least in part, and provide a basis for future work on the subfamily. As such, many of the smaller genera in the subfamily were revised in the Afrotropical Region and two new genera were described. The genus Apochinomma Pavesi, 1881, the only described genus of accurate antmimicking castianeirines from the region, is revised and separated into two species groups based on genitalic and abdominal morphology. The type species, A. formicaeforme Pavesi, 1881, is redescribed and three new species are described in the A. formicaeforme species group: A. malkini sp. nov., A. parva sp. nov. and A. tuberculata sp. nov.. Two new species, A. decepta sp. nov. and A. elongata sp. nov., are described in the A. decepta species group, although an additional species only known from juveniles can also be placed in the latter group. Members of the A. formicaeforme species mimic Polyrhachis ants and are mainly arboreal, while members of A. decepta species group are ground- or grass-dwelling and probably mimic ponerine ants. The genus Cambalida Simon, 1909 is revised and three species are transferred from Castianeira Keyserling, 1879 to Cambalida: C. deminuta (Simon, 1909) comb. nov., C. fulvipes (Simon, 1896) comb. nov. and C. loricifera (Simon, 1885) comb. nov.. An additional species is transferred from Brachyphaea Simon, 1895 to Cambalida: C. fagei (Caporiacco, 1939) comb. nov.. All of these species are redescribed, as is Cambalida coriacea Simon, 1909. Two species, Castianeira depygata Strand, 1916 syn. nov. and C. mestrali Lessert, 1921 syn. nov., are considered junior synonyms of C. fulvipes. The type material of the type species of the genus, C. insulana Simon, 1909 from Annobon Island, is lost, and only immature specimens have been subsequently collected from a nearby island. The species is regarded as a nomen dubium until fresh adult material can be collected. A replacement name, Cambalida simoni nom. nov., is proposed for Cambalida fulvipes Simon, 1909, the latter being a secondary junior homonym of Cambalida fulvipes (Simon, 1896) comb. nov.. The type material of C. simoni is also lost and it too is considered a nomen dubium. Five new species are described: C. compressa sp. nov., C. dippenaarae sp. nov., C. griswoldi sp. nov., C. lineata sp. nov. and C. unica sp. nov.. Castianeira Keyserling, 1879 is the largest genus in the Corinnidae with 131 described species, of which 22 are presently known from the Afrotropical Region. There is a very rich undescribed fauna known from the region, and the variable morphology of its component species would suggest it is polyphyletic and should be divided into several genera. For example, six species are misplaced and have been transferred to or synonymised with species in Cambalida or the new genus Copuetta gen. nov.. In the present study, five species are redescribed and illustrated for the first time based on the type material: C. delicatula Simon, 1909, C. formosula Simon, 1909, C. majungae Simon, 1896, C. phaeochroa Simon, 1909 and C. thomensis Simon, 1909. The female holotype of C. bicolor (Simon, 1890) lacks an abdomen and the species is considered a nomen dubium. The types of several Afrotropical species could not be traced as yet and the species should be redescribed, if possible, based on recently collected material from near their type localities. The ground-dwelling genus Copa Simon, 1885 is one of four genera in the Afrotropical Region that have cryptic colouration that bears a resemblance to that of wolf spiders (Lycosidae), hereafter referred to as cryptic lycosiform colouration. The type species of the genus, C. flavoplumosa Simon, 1885, is redescribed and proposed as a senior synonym of C. benina Strand, 1916 syn. nov. and C. benina nigra Lessert, 1933 syn. nov.. This is possibly the most widespread corinnid in the Afrotropical Region albeit that is has not yet been recorded from any of the islands. A new species, C. kei sp. nov., is described from South Africa. Copa agelenina Simon, 1910, originally described from a subadult female from southern Botswana, is considered a nomen dubium. Although the Madagascan fauna was not included in this revision, nearly 30 new species have been distinguished from museum collections, and once that fauna is revised it will provide an exceptional example of island radiation. In a revision of the Afrotropical species of the ant-mimicking genus Corinnomma Karsch, 1880, Apochinomma semiglabrum Simon, 1896 is redescribed from both sexes, and based on these descriptions it is transferred to Corinnomma as C. semiglabrum (Simon, 1896) comb. nov.. A new species, C. lawrencei sp. nov., is described from Mozambique, Tanzania and South Africa. The taxonomic status of C. olivaceum Simon, 1896 is discussed and the first illustrations of the female genitalic structures are presented. Since no fresh material of this species is available and the female holotype is badly faded, it is not thoroughly redescribed. An English translation of Simon’s (1896) Latin description of C. olivaceum is provided with the intention of more accurately describing the colouration of this species. The arboreal cryptic lycosiform castianeirine genus Echinax Deeleman-Reinhold, 2001, previously known only from South-East Asia, is recorded from the Afrotropical Region for the first time. Copa longespina Simon, 1909 is redescribed and the species is transferred to Echinax as E. longespina (Simon, 1909) comb. nov.. Six new species are described from both sexes: E. clara sp. nov., E. hesperis sp. nov., E. natalensis sp. nov., E. scharffi sp. nov., E. similis sp. nov. and E. spatulata sp. nov.. The genus Graptartia Simon, 1896, presently known only from Africa, is revised. The type species, G. granulosa Simon, 1896, is redescribed and the first genitalic sketches of the species are provided. Two new species, G. mutillica sp. nov. and G. tropicalis sp. nov., are described. Unique amongst African castianeirines, all species of Graptartia are mimics of wingless female velvet ants (Mutillidae). Although the genus Merenius Simon, 1909 is not revised, a single common species, Merenius alberti Lessert, 1923, is redescribed. The species was previously known only from South Africa, and is recorded for the first time from Mozambique, Swaziland and Zimbabwe. While most populations of M. alberti comprise the typical black morph of the species, a red morph is described for the first time here. As part of a field study to identify the potential models of the two colour morphs of M. alberti, spiders were collected by hand and ants by pitfall trapping in the Ndumo Game Reserve in northern KwaZulu-Natal, South Africa. The ants assemblages sampled at 20 sites in the reserve seem to indicate that the black morph is a generalised mimic of black ground-dwelling ants, most likely Camponotus cinctellus (Gerstäcker, 1859), Streblognathus peetersi Robertson, 2002 and Polyrhachis gagates F. Smith, 1858, while the red morph is a mimic of Anoplolepis custodiens (F. Smith, 1858) ants. Lastly, the genus Messapus Simon, 1898, presently placed in the Castianeirinae, is reviewed. The type species, M. martini Simon, 1898, clearly represents two different species, one a corinnine (female lectotype) and the other a castianeirine (male paralectotype). The female is redescribed and the true male described for the first time. Based on the redescription, Messapus is transferred to the Corinninae. Corinna natalis Pocock, 1898 is misplaced and is transferred to Messapus as M. natalis (Pocock, 1898) comb. nov., while Messapus secundus Strand, 1907 is misplaced and transferred to Merenius as M. secundus (Strand, 1907) comb. nov.. A new cryptic lycosiform genus, Copuetta gen. nov., with the type species C. maputa sp. nov., is established to accommodate the castianeirine male paralectotype of M. martini, and its matching female is described for the first time. Castianeira kibonotensis Lessert, 1921 syn. nov. is considered a junior synonym of Copa lacustris Strand, 1916 and the species is redescribed and transferred to Copuetta gen. nov. as C. lacustris (Strand, 1916) comb. nov.. An additional eleven new species of Copuetta gen. nov. are described: C. comorica sp. nov., C. erecta sp. nov., C. kakamega sp. nov., C. kwamgumi sp. nov., C. lesnei sp. nov., C. litipo sp. nov., C. lotzi sp. nov., C. magna sp. nov., C. naja sp. nov., C. uzungwa sp. nov. and C. wagneri sp. nov.. A second new cryptic lycosiform genus, Wasaka gen. nov., is described for four new species from tropical Africa: W. imitatrix sp. nov., W. montana sp. nov., W. occulta sp. nov. (type species) and W. ventralis sp. nov.. A phylogenetic analysis of the subfamily Castianeirinae from the Afrotropical Region was carried out. Forty-one ingroup taxa (Castianeirinae) were included, of which 39 were Afrotropical, one Australasian and one Brazilian. Outgroup taxa included three species of Trachelinae, one Phrurolithinae, two Corinninae and two Corinnidae incertae sedis, with Drassodes sesquidentatus Purcell, 1908 used to root the trees. Only species of Castianeirinae treated in this thesis and known from both sexes were included in the analysis. Analyses performed in Winclada, TNT and PAST all produced similar but very unsatisfactory results, with the outgroups grouping together with part of the Castianeirinae. Consequently, a second analysis was conducted with the exclusion of most of the outgroup taxa (except D. sesquidentatus and Corinninae). These results improved the resolution of the results considerably. but still did not resolve the placement of the Medmassa–Messapus clade within Castianeirinae; these genera can be considered to belong to Corinninae and should hypothetically have been placed outside the Castianeirinae clade. A single analysis produced in PAST produced the most parsimonious tree, with Medmassa–Messapus placed outside the Castianeirinae and each of the Afrotropical castianeirine genera as monophyletic. The results are inadequate to support any systematic changes in the Corinnidae, but future analyses need to include a more diverse range of castianeirine genera from outside the Afrotropical Region to better understand the relationships of the Afrotropical fauna. In the final chapter, the role of Castianeirinae as components of arthropod mimicry complexes is described for three species of ants, Anoplolepis custodiens (F. Smith, 1858), Polyrhachis gagates F. Smith, 1858 and Camponotus fulvopilosus (De Geer, 1778). There are respectively two out of 10, four out of six, and zero out of five species of Castianeirinae forming part of the arthropod complexes associated with these ants. All of these castianeirines are inaccurate (weak/ generalised) mimics of their models except for Apochinomma formicaeforme, which is an accurate (good/specialised) mimic of P. gagates. Colour polymorphism is also described for the first time in four species of Afrotropical Castianeirinae, i.e. Corinnomma semiglabrum, Merenius alberti, Castianeira cf. venustula (Pavesi, 1895) and Copa flavoplumosa. Three of these species are inaccurate mimics of ants, while C. flavoplumosa is a species with a widespread variant with cryptic lycosiform colouration and a nigrito form restricted mainly to tropical forests. High Castianeirinae biodiversity and endemism corresponds to most of the main Biodiversity Hotspots and Centres of Endemism (CE) in the Afrotropical Region: Maputaland-Pondoland-Albany CE (five endemics), Madagascar and Indian Ocean Islands CE (>30 endemics), East African Afromontane Forests CE (four endemics), East African Coastal Forests CE (five endemics), Guinean Forests of West Africa CE (seven endemics) and the Horn of Africa CE (one endemic). No endemic castianeirines have been recorded in the Succulent Karoo and Cape Floristic Region CE’s in southern Africa, although this corinnid fauna of these two CE’s is largely dominated by Trachelinae, most of which are endemics.
Open Access
Aequoreal mediation
(University of the Free State, 2022) Breytenbach, Mané; Smit, J.; Smit, P.; Noble, J.; Raubenheimer, H.; Mosidi, O.
There is something beautiful about the ocean, the intense blueness of it... so tranquil, gliding, and calming. The serene brutality, the sense of awe at the sight of it, the feeling of unknownness. For some, the ocean sparks joy and excitement; for others, fear and unease. There is a certain beauty to the diverse experiences of the ocean. Considering that more than 70% of the earth’s surface is covered with the ocean, one would believe that humans would have explored it thoroughly. However, under 20% is mapped and explored. There is also a multitude of life within the ocean that is not widely discussed. Thus, the essence of this project lies in educating people about the ocean and the marine life and how architecture can promote it. The title of the thesis – Aequoreal Mediation – can be broken into two core parts. Aequoreal is an archaic word that means marine or oceanic. In this thesis, mediation is architecture’s intervention to resolve the disconnection between land and sea. The title frames the thesis and alludes early on to the mediation between man and nature. This thesis aims to capture and frame the beauty of the ocean, allow people to experience it, and to bridge the gap between land and sea. Furthermore, it aims to educate people on what is happening within the ocean and the different marine life in the area. It also aims to encourage a positive experience of, and connotation to, the ocean. Therefore, through this research, this project hopes to uncover a better understanding of the ocean and marine life and explore ways architecture can promote education specifically about the ocean. This research also hopes to assist in diffusing the boundaries set between land and sea.
Open Access
Agricultural credit models: identifying high risk applications
(University of the Free State, 2017) Bougard, Dominique Alyssa; Henning, J. I. F.; Jordaan, H.
The objective of the research was to explore the performance of various statistical credit-scoring models, in order to identify a model that will minimise the misclassification of high-risk applicants, and identify the characteristics that influence repayment ability. The study was conducted in South Africa, with the use of a case study of a South African financial organisation serving the agricultural sector. The data gathered for this study was gathered through a formal agreement with a commercial financial organisation. Logistic regression (LR), probit analysis (PA) and neural network (NN) were used to construct the credit-scoring models that can be used to classify credit applications in the agricultural sector. Results of the LR indicate significance at 10% of the following variables, which may have an impact on classification: medium-term loan, credit history, debt to assets (DTA), net farm ratio, diverse 2, high risk, ownership and experience. The PA results demonstrate the following variables at 10% significance: credit history, DTA, net farm ratio, diverse 2, ownership and experience. The identification of characteristics provides confirmation of characteristics that are of importance to credit research. Financial organisations can use the identification of important characteristics as a method to provide guidance to applicants who apply for loans. Doing so will ensure that the organisation will identify characteristics that ensure that the applicant is accepted by the financial organisation. Applicants for loans can ensure that they possess characteristics that correspond to important characteristics identified by the statistical model. The results from the NN are not easily interpretable; due to “black-box” qualities it was not easy to identify the variables that have an influence on the predicted outcome. The NN did, however, outperform the LR and PA in terms of classification accuracy. Neural networks achieved the highest correctly predicted overall accuracy and a lower percentage of Type II error classifications. Logistic regression and PA have overall classification percentages of 96.06% and 3.94% respectively for classifying Type II errors. The NN had an overall classification accuracy of 98.43% and Type II classification error of 1.54%. The main conclusion from this research is that the statistical methods are able to classify credit applications in the agricultural sector and have the ability to improve accuracy in correctly classifying agricultural applicants. Further research is need to ensure that the correct variables are included in the classification. The classification results of the models are tested and monitored over a period of time to ensure that the accuracy and prediction are acceptable according to the financial organisations. Further research is needed to select the correct variables to be used when supplying credit to smallholder farmers and financial organisations can use the identified important characteristics to provide recommendations and guidance when evaluating applications for loans. Credit applicants can also use these identified important characteristics as a point of reference before applying for the loan at the financial organisation.
Open Access
Agricultural hazardous waste : understanding the hazardous waste cycle in the maize production chain and testing a methodology to collect waste information for the development of a waste register
(University of the Free State, 2014-01) Nell, Arjen Wallace; Esterhuyse, Surina; Reynolds, Dave
The management of agricultural chemicals and waste is imperative in order to ensure proper resource protection and good environmental management. Various studies done in South Africa have illustrated the impact of agricultural waste and chemical mismanagement on the environment and on water resources in particular. Nationally, South Africa aims to manage waste streams by means of a hazardous waste register and locally the provincial departments of Environmental Affairs and Tourism in South Africa should develop such waste registers. This masters project is based on a proposal to develop a hazardous waste source inventory for the Free State province through the Department of Economic Development, Tourism and Environmental Affairs (DETEA) of the Free State Province. The development of a hazardous waste source inventory is important to effectively manage various kinds of hazardous waste sources. Hazardous waste spans various industries (medical waste, industrial waste, agricultural waste) and it can be a huge task to develop a waste register for each province in South Africa. With reference to agricultural waste, the impact of agricultural hazardous waste on water resources is becoming an increasing concern and challenges in the agricultural waste management industry in South Africa are on the rise. The aim of this study was to understand the waste cycle and test a methodology for collecting waste information for the development of a waste database, with a specific focus on agricultural waste in the maize sector. Additional aims included determining whether the agricultural maize sector uses and disposes of its agro-chemicals and other production cycle wastes effectively and to propose alternative management options for more effective management of these chemicals. In order to delimit the study, this study focused specifically on agricultural waste associated with the maize production cycle. The methodology followed in this study was also used in similar studies in other countries (Sweden, France, UK, USA) and involved the development of questionnaires and semi-structured interviews for farmers and chemical distribution agents. Qualitative data obtained from the questionnaires was analysed thematically and quantitative data was analysed using Excel and IBM Statistical Package for Social Sciences (SPSS) version 10. The objective of the study was achieved by developing questionnaires that address questions related to chemical usage and waste in the maize sector. These questionnaires were administered to farmers and chemical distributors in the selected sampling areas. Questionnaire development took place through interviews with parties such as FS Agriculture, Grain SA and pre-testing was done on maize farmers and other relevant people. Results from the questionnaires were used together with data from chemical distributors, databases and literature to develop a baseline indication of chemical usage and waste in the agricultural maize sector. The study showed that determining average volumes of agro-chemicals used in different phases of the maize production sector can be quite complex. This complexity is due to various factors – pesticides may have different names but the same active ingredients, a single pesticide can be used for different pests (by using different concentrations and application methods), in some cases there is uncertainty amongst farmers on how to effectively apply these pesticides, whether the agro-chemical is in a granular or liquid form, and factors like soil type, climate conditions and varying types and amounts of pests and weeds which influences agro-chemical usage in different areas. All these factors make it very difficult to calculate average pesticide volumes used per production cycle just for the maize industry. If one takes into account that agriculture spans a much wider production industry than just maize (e.g. vegetables, cotton etc) the complexity increases even more. This study illustrates the fact that another more effective approach may be required to gather accurate data to populate waste databases for each province. Alternative approaches can include web surveys or voluntary registration by farmers and reporting of chemical type and volumes used either by post or on a web based system. This research addressed key questions related to hazardous waste management in the agricultural maize sector in South Africa and tested a methodology for gathering information to populate hazardous waste registers. The development of hazardous waste registers is a very important waste management tool which the DETEA aims to employ to ensure proper resource protection and waste management, and this study may make valuable contributions towards the development of such waste registers.
Open Access
Agroclimatological risk assessment of rainfed maize production for the Free State Province of South Africa
(University of the Free State, 2010-12) Moeletsi, Mokhele Edmond; Walker, Sue; Landman, Willem A.
English: The risks associated with climate and its variability over the Free State Province is the major determining factor for agricultural productivity, and has a major impact on food security across the province. To improve productivity of agricultural lands, producers and decisions makers have to be provided with relevant agrometeorological information that will enable them to make appropriate decisions. This has lead to the investigation of this agroclimatological risk assessment for maize production in the Free State. The ultimate goal was to characterize the agroclimatological risks impacting negatively on dryland maize production and develop a climate risk tool that will assist the stakeholders in their management of agricultural lands. First, meteorological data needed to perform this study was prepared by looking specifically at filling the missing data gaps and using alternative data in cases where measured data was not available to obtain good spatial distribution of weather stations. Frost was identified as one of the climate hazards affecting the maize plant in the Free State. Three frost severity categories were analysed, namely 2°C, 0°C and -2°C representing light, medium and heavy frost respectively. The onset of frost for all the thresholds was earlier over the northern, eastern and far southeastern parts of the Free State province while places over the western and southwestern parts of the province the first frost dates are later. The northern and eastern parts are also marked by late cessation of frost giving a shorter frost-free period (220-240 days at medium frost severity). The western and southwestern areas mostly have earlier cessation of frost resulting in relatively long frostfree period with ranges from 241 to 300 days at medium frost severity level. Cessation of frost occurring later than normal over the Free State can impact negatively on the maize crop if planted in October and early November, especially over the highlands. Productivity of the crops can also be hampered by earlier than normal onset of frost that affects maize at silking and grain-filling stages. The onsets and cessation of rains together with the duration of the rainy season also play an important role in agricultural planning. Over 300 stations across the Free State were analysed to characterize the rainy season. The onsets of rains were found to be early over the eastern parts of the province with median onsets on or earlier than 10 October. In most areas over the Fezile Dabi and Motheo districts, onsets are between 11 to 30 October while over the Lejweleputswa onsets are mostly between 21 October and 10 November. Most of the western parts of Xhariep experience later than 21 November at 50% risk level. The cessation of rains does not vary much over the Free State with most places having their median last rains between 21 April and 30 April. Rainy season lengths are longer over the Thabo Mofutsanyane district with over 200 days in some places. The ENSO episodes are related to Free State seasonal rainfall variability but only have slight effect on the cessation of rains while onsets of rains showed no differences between El Niño or La Niña phases as compared to all the years. In El Niño years the seasonal rainfall amount is lower than normal, being higher than normal in La Niña years which support findings from other studies. The cessation of rains occurs earlier in El Niño years and later than normal in La Niña years. Agricultural drought is one of the most devastating hazards affecting maize production in most growing periods depending on the location. It is important to plant during periods which minimise drought conditions. In this study a simple water balance model developed by FAO called WRSI was used to quantify drought risk. When using the 120-day maize cultivar as a reference, drought index over most parts of the Lejweleputswa, Xhariep and eastern parts of the Motheo district show high vulnerability (WRSI<40) for October planting dates while other areas have relatively low risk of drought. In December and January planting dates drought index over most parts of the province showed much improvement but places that showed low risk are over the Thabo Mofutsanyane, Fezile Dabi and pockets of northern Lejweleputswa district. Poone AgroClimatic Suitability Index (PACSI) was introduced to integrate all the climate hazards affecting maize production in the Free State. The index in made from the combination of frost probability over the growing period, non-exceedence probability of onset of rains and agricultural drought index. The index was further used to delineate the suitable areas across the Free State for planting maize variety requiring 1420 growing degree days (heat units) to maturity. The findings obtained from the resulting maps show areas of high maize production suitability over the Thabo Mofutsanyane district for mid-October to early November planting dates. Places over Fezile Dabi and northern parts of the Lejweleputswa district also showed high suitability of maize especially for planting from mid-November to end of December. The western and southern Xhariep district area is not suitable for planting maize while other marginal dryland maize production areas include western Motheo, southwestern Lejweleputswa and most parts of the central and eastern Xhariep. To conclude the study, the Free State Maize Agroclimatological Risk Tool (FS-MACRT) was developed to provide agroclimatological risk information important to the production of rainfed maize in the Free State Province. The tool is to be used by the farmers, extension officers, policy-makers and agricultural risk advisors. The tool has two main parts, 1) climatological risk and 2) forecasting. The climatological risk enables the user to obtain drought stress risk for the 100-day, 120-day and 140-day maize cultivars for planting window starting in October to January. The best planting dates based on the risk associated with the climatology onset and cessation of both rains and frost can be determined. Using climate forecasts obtained from the national forecasting centres, drought index can be predicted for different planting dates giving the farmer valuable information when planning for the coming season. The tool also has the functionality of predicting onsets of rains using weather and climate forecasts.
Open Access
Agroclymatic characterization of Lesotho for dryland maize production
(University of the Free State, 2004-11) Moeletsi, Mokhele Edmond; Walker, Sue; Barker, Charles H.
Agro-climatic characterization of Lesotho for dryland maize farming was performed using temperature and rainfall indices in a GIS environment. The temperature and rainfall meteorological parameters were patched for missing data using the UK method for the maximum and minimum temperatures. Missing daily rainfall data was patched using the inverse distance method. Statistical evaluation of the patching methods showed good performance. The spatial distributions of different temperature variables and indices were mapped. Important meteorological parameters were the frost occurrence (first day, last day and duration) and monthly and seasonal heat units. The onset of frost is early (March) over the highland areas while the low- lying areas onset can be as late as June. The last day of frost over the low- lying areas is mostly in August and on the other hand, the highlands last day of frost is in November/December at some places. Rainfall interpolation was done using the kriging method of the geostatistical analyst. Important aspects mapped include monthly averages, seasonal amounts, annual amounts and number of days of high daily rainfall. Wet season (October to April) rainfall was high (>800mm) over the north to northeastern parts of the country while some areas over the east and southern parts received less than 500mm of seasonal rainfall. Climatic potential of maize under dryland farming in Lesotho was investigated using five climatic suitability indices namely: probability of receiving heat units of greater than 1500GDD, probability of a frost-free growing season, probability of seasonal rainfall of more than 500mm, probability of 15-day dry spells during December to February and the slope of an area. For each of the above parameters a coverage layer was prepared in GIS environment and the layers were overlaid to obtain the agroclimatic suitability map of maize in Lesotho. The districts of Butha Buthe, Leribe and Berea are shown to have areas which are highly favorable for maize cultivation under dryland farming while the unsuitable areas are mostly over the high- lying areas (Mokhotlong, Thaba Tseka and Qacha’s Nek) together with other parts of the southern lowlands.