Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2015. / Diabetes mellitus (DM) is an endocrine disorder that is characterised not only by severe hyperglycemia but also altered metabolism of glucose and lipids. It is a major health problem worldwide and its impact is greatly noticed in developing countries due to the lack of adequate medical facilities. Oxidative stress remains the principal factor that actively plays major roles in the onset and progression of diabetes mellitus and its complications. The use of medicinal plants in the treatment of DM has undisputedly gained the attention and interest of researchers throughout the globe mainly because plants have established promising outcomes in the treatment of diabetes. It is evident that the plants’ constituents possess therapeutically potent metabolites that have beneficial effects such as antioxidant, antidiabetic, anticancer, anti-inflammatory and antibacterial activities. Hypoxis hemerocallidea is a native plant that grows in the Southern African regions. H. hemerocallidea is well known for its beneficial medicinal values. In South Africa it is known as the African potato. The main aim of this study was to investigate both the beneficial and also the possible toxic effects of H. hemerocallidea in the kidney and liver tissues of streptozotocin-induced diabetic male Wistar rats by assessing the antioxidant status and selected biochemical parameters in the two studied organs. Diabetes was induced in overnight fasted rats by administration of a single intraperitoneal injection of STZ at a dosage of 50mg/kg in citrate buffer (0.1 M at 4.5 pH). Hyperglycemia was confirmed 72 hours after induction of diabetes using STZ in rats with glucose levels > 15 mmol/l. Treatment with the plants extract commenced on the fourth day after STZ administration via gastric gavage that was done once a day over a 6 week period. The effects of H. hemerocallidea on glucose, body weight, liver and kidney weights, liver function, kidney function and the oxidative status were evaluated after the feeding period.

The principal aim of this work was to compare chosen types of potatoes in terms of occurrence of potato scab and yield. Common scab is a wide - spread potato disease presently. Scabby marks represent the significant defect of consumption potatoes as well as seed potatoes, because they depreciate appearance and quality of potatoes. However, they don{\crq}t affect lower yields directly. The experiment was realized in a private garden. Five different types of potatoes were planted out and the experiment was repeated after two consecutive years. The experiment was evaluated partially at harvest in both years, than followed a particular statistical evaluation. On account of gained results it has been found out that the choice of potato type affects yield as well as the occurrence of potato scab.

Influence of sprout suppression based on CIPC by fogging and amount of storage losses of chips potatoes, with target in losses caused by storage diseases were investigated at temperature 8°C storage. In experiment with varieties Saturna and Pirol higher quantity of storage diseases by Pirol against control were occured after one application of CIPC, Saturna held more storage diseases in control. Identical differences by necessary losses were observed. In another experiment with varieties Saturna and Merlin no differences in amount of storage diseases were registered at double, single or none treatment, neither in quantity of necessary losses. Losses by sprouting were various according to amount of applications of CIPC and duration of storage period.

The object of this research was follow up the cumulation of nitrates in individual kinds of vegetables. Analysed was 240 samples of root crops, cole crops and potatoes distributed in the trade network in Humpolec in the years 2008 - 2010. The measurement results show that all the vegetables went beyond the nitrate permitted limit, according to a law n. 53/2002. The most frequently it was in potatoe samples (50 % samples). The next was a carrot (27 %), kohlrabi (25 %), broccoli (24 %) and celery (17 %). From aspect cumulation of nitrates is parsley unchallenged kind of vegetable. Permitted limit was transcendent in 10 % about less than 1 %. The origin of the vegetables was detected as well. Czech republic had the worst results (52,5 %) because of the high nitrate concentration in potatoes. It is grown by a domestic growers. Spain had 20 % in broccoli and kohlrabi. It is imported to our market. Although the high nitrate concentration in some vegetable samples the vegetable influence the human health in a positive way and it doesn?t make health hazard.

In 2009, there was an experiment with strains of potatos conducted in the region of Soběslav, at an altitude of 614 m. The aim of this thesis was to evaluate production costs, revenues and internal tuber quality in terms of organic and conventional farming system. The work observed dry matter, starch, reducing sugar, chlorogenic acid, vitamin C, nitrates and solanine. An attempt was made on two different strains of potatoes which have different growing season (Impala - very early, Adela - early). Adela variant showed an average of 7.51 t / ha higher yield than the Impala. Higher costs per tonne of potato production were in the conventional way of cultivation. From the evaluation of the internal quality of tubers, there was an apparent influence of the strain and cultivation method on the content of controlled substances. The executed test showed the health of potatoes grown in an organic and conventional way.

Ph.D. (Biochemistry) / Genetically modified (GM) crops were first introduced in the 1980s for the production of medicinal products. Since then, areas designated to GM crops have expanded drastically, with the GM crops grown to enhance agricultural productivity, improve agricultural practices, and as a tool to address potential pressures that will be faced by the agricultural sector and to address the issue of food security. Currently, cultivated GM crops include cotton, maize, rapeseed and soybean, carrying agronomic traits such as herbicide tolerance and insect resistance. Following the genetic modification of crops, three possible outcomes can be anticipated: these outcomes include the GM crop produced being equivalent to its untransformed counterpart, the GM crop differing from its untransformed counterpart with several well-defined characteristics, and the GM crop differing from its untransformed counterpart with a multitude of complex characteristics. In cases where the GM crop is equivalent to the untransformed counterpart, no further testing is needed. In instances where several well-defined and characterised differences are found between the GM crop and the untransformed counterpart, safety assessments are performed targeting these differences. The assessments will determine the impact of these unintended and unexpected alterations of the intended enhancement of the GM crops. However, methods currently used to assess GM crops have been found to be lacking, since they only focus on environmental and product-specific risks. Further evidence is essential, as part of GM crop safety assessment, on the molecular characterisation of these crops. This evidence is based on the potential impact of the transformation event, integration of the transgene into the host plant, as well as unintended alterations such as altered gene expression that may occur to the host plant. These events may assist in the further detection of potential dangers of the GM crop. As a result of these highlighted gaps, a project was formulated to study the unintended genomic alterations that may occur during and following the production of a transgenic plant...

AFRIKAANS: Die vraag onstaan of insette by aartappelproduksie deurentyds ekonomies optimaal gebruik word. Hierdie vraag word al hoe meer deur produsente gevra, veral waar die prysknyptang al hoe sterker gevoel word. Uit ‘n opbrengs oogpunt was stikstof nog altyd ‘n baie belangrike inset. Verliese aan opbrengste kan egter baie groot wees as stikstof ondoelmatig bespaar word. Om optimum stikstoftoedienings te kwantifiseer bly problematies. Die stikstofinhoud van die grond kan gemeet word, maar in hierdie studie is bewys dat die inligting uit hierdie ontledings dikwels misleidend en kan sinvolle aanbevelings nie altyd daarvolgens gemaak word nie. Aan die ander kant, kan die aartappelplant as indikator gebruik word. Die afgelope dertig jaar was baie aandag aan petioolsapekstraksie reg oor die wéreld gegee. Meeste navorsers versap die petiool en gebruik duur laboratorium toerusting om die NO3--konsentrasie te bepaal en maak dan daaruit afleidings. Met hedendaagse tegnologiese ontwikkelings, het vinniger ontledingstegnieke beskikbaar geword. Die Reflectoquant (Merck) is ‘n draagbare instrument wat gebruik word om die NO3--konsentrasie in die aartappelpetioolsap direk te meet. Met kalibrasie-proewe wat deur Omnia gedoen was, is ‘n optimale NO3--konsentrasie reeks (OPTI-reeks) opgestel waarmee stikstof bo-bemestings geskeduleer kon word. Die bepaalde OPTI-reeks is oor twee persele getoets. Die twee persele het verskil in grond tekstuur en ligging. Die Delmas perseel het ‘n hoër klei-inhoud gehad as die Bronkhorstspruit perseel. By die Bronkhorstspruit perseel het verskille tussen die behandelings gouer na vore gekom. Die persele wat laer vlakke van stikstof bemes was, en eerste stikstof bemes is het die laagste NO3--konsentrasie lesings gehad. By die Delmas perseel het hierdie tendens nie herhaal nie. In van die lesingtye het die laer stikstofbemestingsbehandelings hoër ontledings gehad. NO3--konsentrasie lesings, soos vermeld is in die meeste literatuur, het afgeneem oor tyd en gedui op ‘n verdunnings-effek van NO3--konsentrasie in die aartappelplant. Die verdunnings-effek kan toegeskryf word aan die fisiese verdunning van NO3- oor ‘n groter wordende plante, knolle en die gebruik van die NO3- in plantmetaboliese aktiwiteite. Opbrengste en bakkwaliteit van die onderskeie behandelings, was nie verlaag deur die OPTI-reeks te gebruik nie. As in ag geneem word dat ten minste, 45 kg ha-1 stikstof bespaar kon word deur gebruik te maak van die OPTI-reeks, is die metode ‘n baie kragtige ontledingstegniek om stikstof doelmatig te skeduleer. Stikstof sal nie die beperkende faktor in produksie wees, indien hierdie tegniek te gebruik word nie. ENGLISH: The question arises whether inputs are used optimally in an economical way for potato production. This is something that is asked more and more by producers. Nitrogen plays a dominating role in determining yield. Yield losses will be considerable if nitrogen is saved in an unnecessary way. To quantify optimum nitrogen applications can be difficult. Determining the nitrogen content of the soil can be one option, but as was shown in this thesis, this method can lead to incorrect nitrogen applications. The potato plant itself can be used as an indicator for nitrogen applications. For the past thirty years, a lot of emphasis has been placed on petiole sap analyses. Petioles were liquified and then expensive laboratory equipment were used to determine the NO3--concentration, whereafter the recommendations for nitrogen application were made. Analyses are made easier today with modern technological methods and equipment. Direct measurement of the NO3--concentrations in the potato petiole are possible by using the Reflectoquant (of Merck). Omnia Fertilizers conducted many experiments to determine an optimal NO3--concentration range (OPTI-range) to schedule nitrogen applications. In this study the OPTI-range was tested at two sites. The two sites differed in soil texture and district. The Delmas site has a higher clay percentage than the Bronkhorstpruit site. Quicker reactions on the treatments were found at the Bronkhorstspruit site. The plots that received lower nitrogen treatments, were fertilized first and had the lowest NO3--concentrations in the sap. This tendency was not replicated at the Delmas site. The lower nitrogen treatment plots sometimes had higher NO3--concentrations than the higher nitrogen treatments. NO3--concentration readings, as mentioned in most literature, declined over time and is explained by the diluting effect of nitrates in the plant. Not only is there an increase in the potato plants above ground growth, but tuber growth also constitute a big proportion of the biomass at the end of the growth period. Nitrogen is used in all these processes, which contribute to the diluting effect. Yield and tuber quality were not lowered by applying the OPTI-range. The OPTI-range is a good method to manage nitrogen requirements of the potato plant. At least 45 kg ha-1 nitrogen could be saved by using the OPTI-range. Therefore this is a powerful method to determine nitrogen scheduling. Nitrogen will not be the limiting factor in potato fertilization if the OPTI-range is used. / Dissertation (MSc(Agric))--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted

Please read the abstract in the section 00front of this document / Dissertation (Magister Istitutiones Agrariae)--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

Polygalacturonase-inhibiting proteins (PGIPs) are plant proteins believed to playa role in the defence against pathogenic fungi. In this study. it was hypothesized that apple PGIPI could be used to confer enhanced resistance against Verticillium-wilt. a major disease of potato caused by the fungus Verticillillm dahliae. Transgenic lines containing the apple pgip1 gene under control of the enhanced CaMV 35S (e35S) promoter had been generated previously. Stable integration of the transgene into the potato genome was shown by the polymerase chain reaction (PCR) and Southern blot with a DIG¬labelled apple pgip1 fragment as probe. Polygalacturonase (PG)-inhibiting assays (the agarose diffusion assay and reducing sugar assays) were employed to investigate the inhibiting activity of apple PGIP I extracts, prepared from the transgenic potato lines. on the PGs secreted by V. dahliae grown on pectin medium. Inhibition was successful for all but one of the transgenic lines. Active PGIPI was expressed in the leaves of in vitro- and glasshouse grown plants, as well as in roots of in vitro-grown plants. Due to the success of the in vitro inhibition results. it was anticipated that the apple pgip1 transgene would protect the transgenic lines against Verticillium-wilt in a subsequent glasshouse trial. The transgenic lines and untransformed BP I potato control were planted in soil inoculated with V. dahliae microsclerotia and control soil. Assessments of the visual symptoms of yellowing and wilt were made on a scale of 1-5. Colonisation of stem sections was determined by plating onto potato dextrose agar plates. Disease index values were calculated from the symptom and colonisation data. Analysis of variance indicated six lines to be significantly different from the rest when grown in the inoculated soil, but five of them also showed significantly slower senescence symptoms when grown in the control soil. It is proposed that the physiological effect of an extended juvenile phase resulted in the apparent increased disease resistance. This could be caused by transformation or tissue culture¬-induced somaclonal variation of the potato plants. The hypothesis that transformation of the apple pgip1 gene into potato would confer enhanced resistance against Verticillium-wilt was not supported by the data that was obtained. Expression of antifungal genes by pathogen-inducible promoters is a valuable strategy in the development of disease resistant crops of importance. A construct containing the apple pgipl gene under control of the pathogen-inducible gst1 promoter from Arabidopsis thaliana (L.) Heynh was generated. Agrobacterium tumefaciens GV31OI(pMP90RK) was transfonned with the plant transformation vector pCAMBIA2300 containing the gst1 and e35S promoter-pgip1 inserts. A. thaliana was transformed using the floral-dip method, and putative transgenic progeny were selected by kanamycin selection of the seeds. PCR verified the insertion of the transgene into the genomes of T2 and T3 lines. Gene expression from the two promoters was compared by performing PGIP extractions and the agarose diffusion assay. The gst1 promoter was active even without induction by methyl-salicylate. Both constructs led to the expression of active apple PGIP1 against V. dahliae PG in the heterologous plant A. thaliana. / Dissertation (MSc (Plant Biotechnology))--University of Pretoria, 2006. / Plant Science / unrestricted

Studies generally agree on the critical influence of physico-chemical characteristics of raw potatoes on the physico-chemical and sensory characteristics of potato chips. However, the actual magnitude of differences in sensory quality and consumer acceptance of potato chips as a result of differences in the physico-chemical characteristics of raw potatoes are scarcely reported in most studies. This research was conducted to determine the effect of different physico-chemical characteristics of potato samples on the sensory quality and acceptance of potato chips. The potato samples which represented typical variations in physico-chemical characteristics that a potato chip manufacturer experiences were sourced over a six month period. The samples comprised of four potato varieties (A, B, C, D) sourced from five regions (V, W, X, Y, Z). The samples were coded AV, BW1, BW2, CW, CX, DY, DW and DZ. BW1 and BW2 were of the same variety and grown in the same region but harvested at different time periods. The sourcing of potatoes and potato chips were done at the manufacturer’s processing line during regular production. The potatoes were analyzed for physico-chemical characteristics generally reported to influence potato chip sensory quality, i.e. specific gravity (solids contents), starch content and reducing sugars content. After processing, the physico-chemical characteristics i.e. moisture content, colour and oil content of the respective unflavoured potato chip samples were analysed. The sensory qualities of both unflavoured and flavoured (sour cream and onion) potato chips of the respective potato samples were also determined. There were significant differences (p<0.05) in the specific gravity/solids content of the potato samples. The specific gravity and solids content ranged from 1.073 to 1.098g/cm3 and 19.2 to 24.9% respectively. Reducing sugars were not detected in any of the potato samples at a minimum detection level of 0.05 %. The potato chip samples differed significantly (p<0.05) in moisture content, oil content and colour (a * and b* values, chroma, hue angle) with ranges of 1.2 to 1.9 % (moisture), 33.1 to 40.8 % d.b (oil content), 0.39 to 3.69 (a *), 15.88 to 21.26 (b*), 15.93 to 21.37 (chroma) and 79.92 to 88.96 o (hue angle). Descriptive sensory evaluation showed that 6 and 8 of the attributes identified in the unflavoured and flavoured potato chip samples, respectively, differed significantly (p<0.05). Consumer sensory evaluation indicated that there was no clear preference of one chip sample over the others despite of differences observed through descriptive sensory analysis and physico-chemical characteristics. All the chip samples were generally liked. To the manufacturer this research could be regarded as of a quality control nature since the potato chip samples used in this study were of chipping varieties actually used by the manufacturer. The value of this research to the chip manufacturer was the fact that despite of slight differences in the physico-chemical characteristics (specific gravity/solids content and starch content) of potato samples, potato chips of acceptable sensory quality to the consumers were produced. / Dissertation (MSc)--University of Pretoria, 2011. / Food Science / unrestricted