Virginia is the largest apple producing state in the Southeast region of the United States and ranks 10th in most cideries in the US. Natural, or un-inoculated, fermentation methods are of interest to cider producers due to the potential for generating unique and complex aromas and flavors via fermentation with naturally present microbiota. The objective of this study was to determine the effect of common pre-fermentation sulfite addition and pH adjustment on cider chemistry and sensory outcomes for naturally fermented high- and low-tannin apple cultivars. Four treatment conditions were applied to both the high- and the low- tannin cultivars: acidification only, sulfites only, acidification and sulfites, and a control with no pre-fermentation juice chemistry adjustment. The eight experimental ciders were fermented using the Pied de Cuve (PDC) method for natural fermentation. Cider chemistry and sensory parameters were determined, and the treatments imparted key differences in both. Key findings were analyzed for pH, titratable acidity, volatile acidity, malic acid, free/total SO2, yeast assimilable nitrogen (YAN), total polyphenols, residual sugars, and ethanol. For the acidified condition, the pH was lowered to 3.2 using malic acid. Cider pH ranged from 3.36 ± 0.04 to 3.72 ± 0.07, reflecting a general trend toward rising pH over the course of fermentation. Juice tannins were 0.244 ± 0.003 g/L for Harrison and 0.12 ± 0.01 g/L for GoldRush. Tannins decreased during fermentation; however, Harrison ciders maintained a higher range compared to GoldRush. Sensory characteristics were determined using a Descriptive Analysis (DA) with a trained panel which produced 28 descriptors. Results were examined via analysis of variance (ANOVA) and significant differences for apple cultivar, acid adjustment, and sulfite use were found for both chemistry and sensory parameters. The interaction between high- and low- tannin content and sulfite use had the most impact on the cider chemistry and sensory attributes. This study helps to shed light on the extent to which pre-fermentation pH adjustment and/or sulfite additions can influence the outcomes of natural cider fermentation in both high- and low-tannin cultivars. / Master of Science in Life Sciences / Cider, also known as "hard cider," is an alcoholic beverage fermented from apples. Virginia is the 6th largest apple producing state in United States and ranks 10th in number of cideries. Natural fermentation uses microorganisms that are present in the environment to ferment cider. This type of fermentation is of interest to the cider industry due to the unique aromas and flavors produced by this method. The objective of this study was to determine the effect of common fermentation management strategies: pre-fermentation sulfite addition and acid adjustment, on cider chemistry and sensory outcomes for naturally fermented high- and low-tannin apple cultivars. Eight experimental ciders were fermented using the Pied de Cuve (PDC) method, which is a type of natural fermentation. Cider chemistry and sensory outcomes were evaluated. The experimental treatments and their interactions imparted key differences in both chemical and sensory outcomes. Cider pH ranged from 3.36 ± 0.04 to 3.72 ± 0.07 reflecting a general trend toward rising pH over the course of fermentation. Juice tannins were 0.244 ± 0.003 g/L for Harrison and 0.12 ± 0.01 g/L for GoldRush. Tannin concentration generally decreased during fermentation; however, Harrison ciders maintained a higher range compared to GoldRush. Sensory characteristics of each cider were determined using a Descriptive Analysis (DA) study, a with a trained panel which produced 28 descriptors, 19 of which were significant. The interaction between high- and low- tannin content and sulfite use had the most impact on the cider chemistry and sensory attributes. This study helps to inform cider producers regarding the impacts of pre-fermentation acid or sulfite additions on natural fermentation, and how those impacts may vary among high- and low-tannin apple cultivars.

no abstract provided by author / Master of Science

This problem purposes not only to show the relationships, if any, that exist between terminal growth and yield, but also to ascertain the statistical methods that may be best adaptable. / Master of Science

Cider production volume has increased over 800% in the past 5 years in North America. This rapid growth of the cider industry coupled with traditional craft approach to cider making necessitates increased research on apple chemistry, processing, and fermentation strategies for cider production. A common problem in cider is the sulfur off-aromas production by yeast during fermentation. Fermentation of cloudy juice is often associated with sulfur off-aromas in white wine production; therefore, pre-fermentation juice clarification is an important and routine step in white winemaking practice. However, cider makers are often reluctant to clarify juice pre-fermentation due to beliefs that pre-fermentation juice clarification will reduce the concentration of yeast assimilable nitrogen (YAN) and polyphenols; thus, negatively impacting cider quality. In this study, different clarification methods were applied on York apple juice, and both raw and clarified juices were fermented into cider. The impact of pre-fermentation juice clarification treatments on the juice and finished cider chemistry was assessed by comparing the primary juice and cider chemistry, YAN concentration and amino acid composition in juice, polyphenol concentration and composition in juice and cider. Different clarification treatments affected the YAN concentration and amino acid composition differently. Polyphenol concentration in juice was decreased and individual polyphenol composition was different after the clarification (p<0.05), but these changes did not persist into the finished cider. The effect of pre-fermentation juice clarification on sensory properties of cider warrants further investigation. Future research should also include the development of appropriate analysis for polyphenol measurement in apple juice and cider. / Master of Science in Life Sciences

Though the cidermaking process is very similar to that of winemaking, there is a lack of scientific knowledge as to how orchard management practices and fruit storage affect the quality of the resulting cider. This research examined how both varying harvest maturities and post-harvest storage temperatures and durations in apple cultivars Dabinett, Brown Snout, and York impacted fruit quality as well as the chemistry of the juice and cider. Harvest intervals of two weeks before maturity, at maturity, and 2 weeks after maturity resulted in significant differences in fruit quality and juice chemistry, but few of these differences persisted in cider chemistry. Nonetheless, differences in concentration of some individual polyphenols determined by UPLC-MS were observed in ciders made from fruit harvested at different stages. For example, cider made from optimally mature Dabinett had over 250% the concentration of procyanidin B5 that was found in cider made from fruit harvested earlier or later. The storage treatments also resulted in substantial differences in fruit and juice chemistry, but fewer differences in cider chemistry. As with the harvest maturity experiment, differences in individual polyphenols were detected, with ciders made from cv. York having 20% higher epicatechin concentration when stored for 6 weeks at 1°C rather than 10°C. Finally, the accuracy of the Folin-Ciocalteu (FC) assay, commonly used for quantification of total polyphenols in fruit juices and fermented fruit beverages was critically evaluated. Reducing sugars in the sample matrix did not affect the results of the FC assay, whereas the presence of the amino acid tyrosine resulted in significant overestimation of total polyphenols in fruit juice by the FC assay. / Master of Science in Life Sciences / Cider production and consumption in North America has increased rapidly in recent years. Though cidermaking is in many ways similar to winemaking, there is a lack of scientific knowledge as to how orchard management practices and fruit storage affect the quality of cider. This study examined how varying the harvest date and the ways in which apples are stored after harvest but before cidermaking can affect cider quality. This work was conducted using the apple cultivars Dabinett, Brown Snout, and York. We found that differences in fruit maturity at harvest as well as post-harvest storage parameters impacted fruit, juice and cider quality. However, the differences observed in cider quality as a result of these treatments were much more subtle than the observed differences in fruit and juice quality. This work indicates that in order to accurately assess the impact of orchard management and post-harvest treatments on cider quality, cider should be made and evaluated, rather than assuming that the differences observed in fruit and/or juice will directly translate into cider quality differences.

The state of Virginia was analyzed to establish its suitability for grape culture. This investigation occurred in two phases: a small scale analysis that encompassed the entire state, and a large scale analysis which focused on site selection at the local level. After identifying regions across the state in terms of their viticulture potential, a study area was chosen from within the highest ranking region. This study area was the focus for the local-scale site potential analysis. First, to delineate regions across Virginia that had greater or lesser viticulture potential from a physical and climatological basis, weather station data were collected for minimum winter temperatures, maximum summer temperatures, precipitation, length of growing season, and day versus night temperature differentials. In addition, elevation and slope models were constructed to complement the climatic variables in identifying areas that contained factors most conducive to grape production. To validate this regional assessment, the history of fruit industries within the state are outlined geographically to display the evolution of the fruit industries, and to establish the factors which have shaped the current fruit landscape. Secondly, at the local scale, a Geographic Information System (GIS) approach was used to identify sites at the county scale that had greater or lesser viticulture potential from a physical basis. Composite maps, constructed by individual counties in the state, were produced from a series of physical databases. The individual databases (sources and resolution in parentheses) included land-use (Virginia Gap Analysis; 30meter² resolution), slope, aspect, and elevation (USGS 1:24,000 Digital Elevation Model; 30meter²), and soils data (USGS Digital Line Graph (DLG-3)). Each physical feature layer was given a numerical classification, then all layers were combined to produce a 0 to 100 scale in the final, composite image. Given this model of potential vineyard suitability, existing fruit operations in select counties were geo-located on each feature layer using a Global Positioning System (GPS: 1-2meter accuracy). Actual data on occurrences of frosts, minimum winter temperatures, and other site variables were collected from these fruit operations and surrounding weather stations as a sample to validate the model. A strong correlation between areas containing characteristics of current fruit acreage--namely apple--and sites high in potential for viticulture according to the model. Studying the history of geographic distribution of apple and grape industries across the state reinforces the regional assessment of viticulture potential, formulated by the climatic and topographic analysis. Employment of GIS approach at the local site scale was shown to be an effective tool for site selection at the local scale with certain caveats. In addition, the evaluation procedure integrating GIS and GPS technologies allows us to visually assess the distribution pattern of each of the factors employed individually; and, in turn, physically identify and locate areas of viticulture potential created from the combination of those factors. / Master of Science

The fate of E. coli O157:H7 and Salmonella spp. during osmotic dehydration of apples was determined at different processing temperatures, times and calcium chloride (CaCl2) concentrations. Apple slices were inoculated to achieve an 8 log CFU/ apple slice concentration of a five strain mixture of E. coli O157:H7 or Salmonella spp. and were soaked in sucrose solutions (60% w/w). In the first study, apple slices were subjected to osmotic dehydration at three different temperatures: 20°C, 45°C and 60°C. In a second study, CaCl₂ was added in the sucrose solution at concentrations of 2%, 4% and 8% to determine its efficacy as an antimicrobial agent. The storage effect of osmotic dehydrated apples on pathogen survival was also tested for seven days at 4°C. Samples were withdrawn at appropriate time intervals, diluted with 0.1% peptone water and surface plated onto recovery media. Recovery of E. coli O157:H7 was compared on Tryptic Soy Agar + 50 ppm nalidixic acid (TSAN) and MacConkey Sorbitol agar (MCS). Recovery of Salmonella was compared on TSAN and XLD agar. There was lower microbial reduction at the lower temperatures tested with approximately 1.0 and 3.0 log CFU/apple slice reduction at 20°C and 45°C, respectively. The population reduction of cells was highest at 60°C, with an approximate five log reduction for both microorganisms (P<0.001). CaCl₂ used as an additive in the osmotic solution, was associated with slightly higher reduction of both E. coli O157:H7 and Salmonella spp. Greater than a 5 log reduction was observed when the combination of CaCl₂ (8%) and 60°C processing temperature was used. During refrigerated storage E. coli O157:H7 and Salmonella decreased by approximately 4.5 log CFU/apple slice, but were still recoverable via direct plating at Day seven. The results of this study show that the survival of E. coli O157:H7 and Salmonella in osmotically dehydrated fruit is influenced by the osmotic processing method used and the level of additive (i.e., CaCl₂) utilized. Parameters associated with decreased survival of pathogens, and therefore, improve product safety, include increasing temperature and time of processing and increasing concentration of CaCl₂. However, E. coli O157:H7 and Salmonella in artificially contaminated apple slices, survived osmotic dehydration processing and subsequent storage under processing and storage parameters of this study. Therefore, processors who produce osmotically dehydrated fruit must consider the potential food safety impact of the osmotic dehydration processes they choose. / Master of Science

Thesis (MScAgric)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The deregulation and the following restructuring of the South African fruit industry in 1996 had a significant influence on the decision-making environment that participants in the industry were used to. As new exporters entered the industry many new market opportunities arose. However at this same period in time export-earnings from the most important traditional markets came under pressure. A drastic increase in the supply of fresh apples from other Southern Hemisphere countries like Chile as well as a highly fragmented South African marketing structure are believed to be the most important reasons for the decline in exportearnings. The aim of this study is to focus on the international competitiveness of the South African apple industry in comparison to the competitiveness of the Chilean industry, with specific reference to the competition between the two countries on the European market for fresh apples. The study is introduced by a historical view as well as a glance at recent realities within the South African as well as the Chilean apple industry. Aspects that have lead to the growth and development regarding production as well as exports within both industries will be indicated. Historical international trade performance of both industries is discussed as international trade performance is a prerequisite for international competitiveness. Theoretical principles of competitiveness and competitive advantage is given with specific focus on the most recent theoretical viewpoints concerning competitive advantage and the reaching thereof The work of Michael Porter (1990) is used as a starting point in order to construct a framework with which the national competitive advantage of a specific industry, with a specific nation, can be explained. According to Porter ( 1990) national competitive advantage can be defined as the specific characteristics of a nation's national circumstances that enables a specific industry within that nation to create and maintain competitive advantages. National competitive advantage a measured according to four so-called broad determinants of national competitive advantage, namely industry structure, strategy and competition (first determinant), factor conditions, related and supporting industries and demand conditions as the forth determinant. A number of more recent definitions and describing literature on competitive advantage is used in order to expand Porter's so-called "diamond-analyses" for specific use to analyze an industry that produces a perishable product. An important prerequisite concerning the analyzing of competitiveness, is the presence of a relative or comparative component. Industry specific technical literature is used in order to make comparative descriptions within the above mentioned framework. This framework (expanded Porter-model) is used in order to compare the Chilean apple industry with the South African industry on the basis ofthe four broad determinants of national competitive advantage. In this way a complex description of the varied national and international industry environments within which the two industries operate, is done. It is very clear that international exposure on production as well as on marketing level together with excellent natural resources is the most important contributors to the national competitive advantage of the Chilean apple industry. The exceptional natural resources and very good weather conditions for growing apples together with growers' exposure to consumer demands are important contributors to the production of high quality fruit. Marketers and exporters show valuable market-discipline and they have easy access to relevant market information. These aspects strengthen the competitiveness of the Chilean apple industry. If the South African apple industry want to be competitive in future, it is absolutely essential that scarce resources such as soil and water is well-managed and conserved. International exposure and technological innovation on production level is also very important. Market information will have to be more easily accessible and exporters will have to show significant market discipline. It is also important that there will not be any uncertainties as far as property rights is concerned, as this will scare investors. It is of utmost importance that the South African government will work towards creating a home base that will have a positive effect on the obtaining and the maintaining of national competitive advantage. This study give participants within the South African apple industry a thorough description of the varied decision-making environments to which the Chilean and the South African apple producer is subjected to. Differences within this decision-making environments is emphasized and there is an indication of what the direct influence of this differences have on the South African industry. Possible future changes concerning the various macroenvironments of the two industries is analyzed and an indication is given on how these changes will influence the obtaining and maintaining of national competitive advantage in future. / AFRIKAANSE OPSOMMING: Die deregulering en die gevolglike herstrukturering van die Suid-Afrikaanse vrugtebedryf in 1996 het die besluitnemingsomgewing vir alle deelhouers binne die Suid-Afrikaanse vrugtebedryf drasties verander. Die toetrede van verskeie nuwe uitvoerders het beteken dat nuwe bemarkings-geleenthede benut kon word, maar ongelukkig het uitvoerverdienste op die tradisioneel belangrike markte op dieselfde tydstip onder groot druk gekom. 'n Dramatiese toename in die voorsiening van vars appels vanuit ander Suidelike-Halfrond-lande, soos Chili, tesame met 'n gefragmenteerde Suid-Afrikaanse bemarkings-opset word as die belangrikste redes vir die dating in uitvoerverdienste aangevoer. In hierdie ondersoek word daar gefokus op die internasionale mededingendheid van die Suid-Afrikaanse appelbedryf relatief tot die mededingendheid van die Chileense bedryf, met spesifieke verwysing na die mededinging tussen die twee lande in die Europese mark vir vars appels. Die studie word ingelei deur 'n geskiedkundige oorsig sowel as 'n blik op huidige realiteite binne die Suid-Afrikaanse- sowel as die Chileense appelbedrywe. Die verloop van gebeure wat tot die groei en ontwikkeling ten opsigte van produksie sowel as uitvoere binne beide bedrywe gelei het, word aangedui. Die bereiking van intemasionale handelsukses word as voorvereiste vir intemasionale mededingendheid aangevoer. Geskiedkundige intemasionale handelsprestasie van beide bedrywe word dus ook uiteengesit. 'n Uiteensetting van teoretiese grondbeginsels van mededingendheid en mededingende voordele word aangebied met die fokus op die jongste teoretiese sienings betreffende mededingende voordeel en die bereiking daarvan. Die werk van Micheal Porter (1990) word as vertrekpunt gebruik ten einde 'n raamwerk te konstrueer waarmee die nasionale mededingende voordeel van 'n bepaalde bedryf, gesetel binne 'n bepaalde nasie, omskryf kan word. Volgens Porter (1990) word nasionale mededingende voordeel omskryf as die bepaalde karaktertrekke van 'n nasie se nasionale omstandighede wat spesifieke bedrywe binne daardie nasie in staat stel om mededingende voordele te skep en te behou. Nasionale mededingende voordeel word gemeet aan die hand van vier sogenaamde bree determinante van nasionale mededingende voordeel, naamlik bedryfstruktuur, bedryfstrategie en bedryfskompetisie (wat gesamentlik die eerste determinant vorm), faktorkondisies, verwante en ondersteunende industriee asook vraagtoestande. Hierdie vier determinante omskryf die totale omgewing (home base) waarbinne 'n bepaalde bedryf opereer. Verskeie meer onlangse definisies en beskrywende literatuur betreffende mededingende voordeel is aangewend om Porter (1990) se sogenaamde "diamant-analise" uit te brei en meer toepaslik te maak op 'n bedryf wat 'n bederfbare kommoditeit produseer. 'n Belangrike voorvereiste betreffende die analisering van mededingendheid, is die teenwoordigheid van 'n relatiewe of vergelykende komponent. Bedryfspesifieke tegniese literatuur is dus verder aangewend ten einde vergelykende beskrywings binne die genoemde raamwerk te doen. Die raamwerk (uitgebreide Portermodel) is gebruik ten einde die Chileense appelbedryf met die Suid-Mrikaanse appelbedryf te vergelyk aan die hand van elk van die genoemde determinante van nasionale mededingende voordeel. Op hierdie wyse is 'n komplekse beskrywing van die onderskeie nasionale en internasionale bedryfsomgewings (home bases) waarbinne die twee bedrywe opereer, verkry. Omvattende internasionale blootstelling op produksie- maar veral op bemarkingsvlak tesame met uiters gunstige klimatologiese toestande en baie goeie natuurlike hulpbronne, blyk die belangrikste aspekte te wees wat hydra tot nasionale mededingende voordeel van die Chileense appelbedryf. Die gunstige klimatologiese toestande en die kwaliteit van die natuurlike hulpbronne tesame met die feit dat produsente die verbruikersbehoeftes van die verskillende wereldmarkte ken, dra by tot die produksie van goeie kwaliteit vrugte. Die vaardigheid en hoe vlak van intemasionale blootstelling waaroor bemarkers/uitvoerders beskik, tesame met die toepassing van markdissipline, is verdere aspekte wat die mededingendheid van die Chileense bedryf versterk. Indien die Suid-Afrikaanse appelbedryf in die toekoms steeds mededingend wil wees en nuwe nasionale mededingende voordeel wil skep en handhaaf, is dit van kardinale belang dat beskikbare, skaars hulpbronne soos water en grond oordeelkundig bestuur en aangewend moet word. Intemasionale blootstelling en tegnologiese innovasie met betrekking tot produksie is van kardinale belang. Dit is verder belangrik dat mark-inligting meer toeganklik sal word en dat uitvoerders die nodige markdissipline sal toepas en handhaaf. Dit is belangrik dat onsekerheid betreffende eiendomsreg vermy sal word omdat dit kan lei tot beleggerswantroue. Dit is van kardinale belang dat die Suid-Afrikaanse regering sal streef daarna om 'n home base te skep wat positiefbydra tot die bereiking en handhawing van nasionale mededingende voordeel. Die studie bied dus aan deelhouers binne die Suid-Amerikaanse appelbedryf 'n omvattende beskrywing van die onderskeie besluitnemingsomgewings waaraan die Chileense sowel as die Suid-Mrikaanse appelprodusent blootgestel ts. Verskille binne hierdie besluitnemingsomgewings word uitgelig en daar word aangetoon wat die direkte invloed van hierdie verskille op die mededingendheid van die Suid-Mrikaanse bedryf mag wees. Moontlike toekomstige veranderinge betreffende die onderskeie makro-omgewings van die twee bedrywe word ondersoek en daar word aangedui hoe hierdie veranderinge die bereiking en handhawing van nasionale mededingende voordeel in die toekoms sal belnvloed.

Thesis (MScAgric)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Characterizing the genetic structure of a pest population can provide an understanding of the factors influencing its evolution and assist in its ultimate control. The aim of the present study was to characterize the genetic structure of woolly apple aphid Eriosoma lanigerum (Hausmann) populations in the Western Cape Province in South Africa. Since this economically important apple pest has not previously been characterized at molecular level, it was necessary to evaluate methods for determining the genetic structure of E. lanigerum populations. Two different molecular techniques were evaluated viz. random amplification of polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP). This study represents the first application of the latter technique to members of the Aphididae. Aphids were sampled from four regions in the Western Cape in South Africa viz. Elgin, Ceres, Vyeboom and Villiersdorp. A spatially nested sampling design was used to establish the distribution of the genetic variance of aphids. A total of 192 individuals from 13 farms were analysed. Ten RAPD primers were chosen for analysis from an initial assay of 25 after fragment reproducibility had been confirmed. For AFLP analysis three different rare-cutting restriction enzymes were evaluated for AFLP analysis, viz. EcoRI, SseI and MluI. The latter yielded the best results in combination with the frequent-cutting enzyme MseI. Twenty-five AFLP selective primer pairs were evaluated, out of which five were chosen for analysis of the total population. Two hundred and fifty AFLP fragments and 47 RAPD fragments were scored for analysis. Both analyses indicated that a low level of genetic variation was apparent in E. lanigerum populations and that no differentiation resulted from geographic isolation. From RAPD analyses it was deduced that all variation could be attributed to differences between individuals. AFLP analysis indicated that, whereas genetic differences in E. lanigerum populations between orchards were negligible, a significant portion of genetic variation could be attributed to differences between farms and individuals within farms. Therefore, AFLP analysis allowed for finer discrimination of the genetic structure of E. lanigerum populations than RAPD analysis and is recommended for studies of other aphid species. The fact that most of the genetic variation present in E. lanigerum populations could be found on small spatial scales indicated that sampling individuals over a wide geographic area was an ineffective way of detecting the genetic diversity present in E. lanigerum populations. The low level of variation in populations is most likely due to the exclusive occurrence of parthenogenetic reproduction, founder effects (including distribution of infested plant material from a limited source) and selective factors such as the use of resistant rootstocks or pesticides. Furthermore, the low level of variation found indicated that the possibility of controlling E. lanigerum in the Western Cape using host plant resistance is favourable. Thus, plant breeders developing resistance to E. lanigerum can expect plant entries to be exposed to most of the genetic diversity present in Western Cape populations, regardless of location. / AFRIKAANSE OPSOMMING: Die bepaling van die genetiese struktuur van 'n landboukundige plaagpopulasie kan lei tot begrip van die faktore wat die populasie beïnvloed en kan uiteindelike beheer vergemaklik. Die doel van die huidige studie was om die genetiese struktuur van die appelbloedluis Eriosoma lanigerum (Hausmann) in die Wes-Kaap Provinsie van Suid-Afrika te bepaal. Aangesien hierdie belangrike appelplaag nie van tevore op molekulêre vlak bestudeer is nie, was dit nodig om metodes vir die bepaling van die genetiese struktuur van E. lanigerum populasies te evalueer. Twee molekulêre tegnieke is geëvalueer, nl. lukraak geamplifiseerde polimorfiese ONS (RAPD) en geamplifiseerde fragment-lengte polimorfismes (AFLP). Hierdie studie is die eerste om laasgenoemde tegniek te gebruik om lede van die Aphididae te bestudeer. Plantluise is verkry van vier verskillende gebiede in die Wes-Kaap Provinsie van Suid-Afrika nl. Elgin, Ceres, Vyeboom en Villiersdorp. 'n Hierargiese sisteem is gebruik om die verspreiding van die genetiese variasie van plantluise te bepaal. In totaal is 192 individue van 13 plase geanaliseer. Tien RAPD inleiers is gekies uit 'n analise van 25 verskillende inleiers nadat fragment reproduseerbaarheid bevestig is. Drie verskillende restriksie ensieme is geëvalueer vir AFLP analise nl. EcoRI, SseI en Mlul. Die beste resultate is verkry toe MluI saam met MseI gebruik is. Vyf-en-twintig AFLP selektiewe inleier pare is geëvalueer waarvan vyf gekies is vir analise van die totale populasie. Twee-honderd-en-vyftig AFLP fragmente en 47 RAPD fragmente is gedokumenteer vir analise. Beide RAPD en AFLP analises het getoon dat daar 'n lae vlak van genetiese variasie in E. lanigerum populasies is en dat geen differensiasie as gevolg van geografiese isolasie ontstaan het nie. Uit RAPD analise is daar afgelei dat al die variasie toegeskryf kon word aan verskille tussen individue. AFLP het aangetoon dat alhoewel verskille in E. lanigerum populasies tussen boorde laag was, kon 'n hoë persentasie van die variasie toegeskryf word aan verskille tussen plase en individue binne plase. AFLP analise het meer insig in die genetiese struktuur van E. lanigerum populasies verskaf, en word dus aanbeveel vir studies van ander plantluise. Omdat meeste van die genetiese variasie oor klein geografiese afstande verkry word, is steekproefueming oor groot gebiede 'n ondoeltreffende manier om die genetiese variasie binne 'n monster te meet. Die lae vlak van genetiese variasie is waarskynlik te wyte aan partenogenetiese vermeerdering, stigter gevolge (insluitend verspreiding van geïnfesteerde plantmateriaal vanaf 'n beperkte bron), sowel as selektiewe faktore soos die gebruik van bestande onderstokke en insekdoders. Verder dui die lae vlak van variasie aan dat die moontlikheid vir beheer deur gasheerplantbestandheid goed is in die Wes-Kaap. Planttelers kan verseker wees dat hulle plante blootgestel sal wees aan meeste van die genetiese variasie in die Wes-Kaap appelbloedluis populasies ongeag hulle ligging.

The aim of this thesis is the analysis of applications, suitable for teaching mathematics using mobile devices such as iPad and tablets using Android or Windows. Selected applications are classified according to thematic chapters plan with respect to the phase creation concepts of process. It was also realized instructional hours with the selected app for the Android platform.