In this study the stability and nutrient removal performance of aerobic granules under variable operating pH and variable growth medium was investigated. The results indicated that alkaline pH (pH=9) inhibited nitrogen and phosphorus removal. Moreover, high pH induced granules breakage and resulted in an increased biomass concentration in the effluent. On the other hand, acidic pH (pH=6) did not have significant impacts on stability and nutrient removal efficiency of granules. Changing the growth medium from acetate-based wastewater to municipal wastewater resulted in loss of biological phosphorus removal while ammonium and COD removal stayed the same. The granules disintegrated during the first two weeks after changing the feed; re-granulation of the biomass was observed after the acclimation of bacteria to the new growth medium. However, the granules breakage did not exert significant impact on settling property of biomass.

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Existing research shows that plants produce less root when growing alone than when growing in competition with other plants. When plants under root competition over-allocate resources to roots at the cost of reproduction, it represents a Tragedy of the Commons. I constructed simulation models to determine the circumstances likely to give rise to a Tragedy of the Commons, and explore mechanisms by which plants may solve it. I grew plants in nutrient-rich transparent gel, allowing me to quantify root growth and development without destructive sampling. My plants responded positively to additional space and the presence of a competitor at full nutrient treatment levels, and negatively to those same conditions between low phosphorus treatment levels, demonstrating nutrient mediation of the direction of plant response to an added competitor with additional space. This effect may feature self / non-self recognition by roots. Since the hard barrier in these studies blocks nutrients, roots, and root signaling compounds from passing between the plants in the barrier treatment level, existing studies cannot tease apart the effects on plant development of these individual factors. I add a semi-permeable membrane treatment level, which allows nutrients and signaling compounds to pass while preventing root growth between sides.

Cyclamens are deemed an essential cold season crop for supplementing the income of commercial growers during winter. However, cyclamens have the reputation of being a demanding commercial crop mainly due to difficulty in successful crop cultivation, lengthy production time and production costs. The economic and environmental landscape in South Africa dictates that careful consideration be given to reducing production time and costs, but still improving the quality of the commercial crop for market readiness. Growth medium are considered an important factor contributing significantly to the quality of commercially grown container cyclamens in a controlled environment. The focus of this study was on establishing the most suitable growth medium for commercially grown cyclamens in a South African environment in order to improve the quality of the commercial crop. Only one F1 variety of cyclamen was used as the sample population with a sample size of five plants per growth medium mixture planted according to a randomised block design in a specified area within a greenhouse. Seven commercially available growth medium mixtures, five locally available and two imported, were subjected to a typical production cycle of commercial cyclamens in a controlled greenhouse. The growth medium mixtures for comparison were Cyclamen Mix; 45 Mix; 50% Cyclamen Mix - 50% 45 Mix; 49 Mix; 7 Mix; coarse coir; Klasmann base 4 Substrate mix . The measuring instrument used in the study was adapted from existing instruments used in the comparison of cyclamens and growth medium. It included various measurements and observations: Plant height, plant diameter, plant weight, number of leaves, leaf width, foliage fresh weight, number of flowers, diameter of tuber and root fresh weight. The results obtained in the comparison determine the most suitable growth medium for container cyclamens for South African circumstances. The physical properties of peat retain water for a longer time which is beneficial for the production of container cyclamen. The results of this study therefore indicate that growth mediums containing peat performed better than mediums containing no peat. / Agriculture and  Animal Health / M.Sc. (Ornamental Horticulture)

Cyclamens are deemed an essential cold season crop for supplementing the income of commercial growers during winter. However, cyclamens have the reputation of being a demanding commercial crop mainly due to difficulty in successful crop cultivation, lengthy production time and production costs. The economic and environmental landscape in South Africa dictates that careful consideration be given to reducing production time and costs, but still improving the quality of the commercial crop for market readiness. Growth medium are considered an important factor contributing significantly to the quality of commercially grown container cyclamens in a controlled environment. The focus of this study was on establishing the most suitable growth medium for commercially grown cyclamens in a South African environment in order to improve the quality of the commercial crop. Only one F1 variety of cyclamen was used as the sample population with a sample size of five plants per growth medium mixture planted according to a randomised block design in a specified area within a greenhouse. Seven commercially available growth medium mixtures, five locally available and two imported, were subjected to a typical production cycle of commercial cyclamens in a controlled greenhouse. The growth medium mixtures for comparison were Cyclamen Mix; 45 Mix; 50% Cyclamen Mix - 50% 45 Mix; 49 Mix; 7 Mix; coarse coir; Klasmann base 4 Substrate mix . The measuring instrument used in the study was adapted from existing instruments used in the comparison of cyclamens and growth medium. It included various measurements and observations: Plant height, plant diameter, plant weight, number of leaves, leaf width, foliage fresh weight, number of flowers, diameter of tuber and root fresh weight. The results obtained in the comparison determine the most suitable growth medium for container cyclamens for South African circumstances. The physical properties of peat retain water for a longer time which is beneficial for the production of container cyclamen. The results of this study therefore indicate that growth mediums containing peat performed better than mediums containing no peat. / Agriculture and  Animal Health / M.Sc. (Ornamental Horticulture)

Made available in DSpace on 2016-12-08T16:44:32Z (GMT). No. of bitstreams: 1 PGPV07MA022.pdf: 293867 bytes, checksum: 7be800f613b76704595bb5911a0eeab8 (MD5) Previous issue date: 2007-02-26 / The apple culture has great social and economic importance for the South region of Brazil and in the 2003/04 crop season produced approximately 970,000 tons. During the 1995/96 crop season, a diferente symptom from the mosto f symptoms observed in apple fruit and branches were evidenced in Rio Grande do Sul and Santa Catarina orchards. After etiological studies, it was determined the occurrence of fungus Cryptosporiopsis perrennans. This pathogen can cause rota round of 15% on storage apples and for the time been there is few studies about the patogen and the epidemiology of disease. The purpose of this work was to study the development and the production of C. perennans spores over diferente cultures medium with and without fungicides, and to determinethe effect of temperature and humidity periods over the Bull s eye roto n Fuji apple. The experiments carriedout were the following: a) evaluatoon of the effect of potato-dextrose-agar (PDA), malt extract (MEM) and V8 juice (V8) médium on the development and production of spores by 9 isolates of C. perennans; b) evaluation of sensibility in vitro of C. perennans to six diferente concentrations of the fungicides captan, cooper hidroxide, dithianon, mancozev and trifloxistrobin diluted in PDA; c) evaluation of incidence and severity of the Bull eye s rot when Fuji apples inoculated with C. perennans had been submited to diferente combinations of humidity and temperature periods. The results showedthat the medium AEM and V8 promoted better stimulus to mycelium growth and that five C. perennans isolates produced more spores when cultivated in V8 and four isolates in MEM. The diferente fungicides tested were eficiente to control C. perennans micelial growth, however the most promising results were obtained the fungicides dithianon and mancozeb. Higher incidence and severity of the Bull eye s roto n Fuji apples were obteined with 20 hours of incubation at 22°C / A cultura da macieira tem grande importância sócio-econômica para a região sul do Brasil tendo atingido no ciclo 2003/04 aproximadamente 970.000 toneladas. Nos ciclos vegetativos de 1995 e 1996, um sintoma diferente daqueles relatados até então no Brasil em frutos e ramos da macieira foi constatado em pomares do Rio Grande do Sul e de Santa Catarina. Após o estudo de sua etiologia, identificou-se a ocorrência do fungo Cryptosporiopsis perennans. Este patógeno pode causa podridões ao redor de 15% das maçãs no armazenamento e, no presente, há poucos estudos que contribuam ao conhecimento do patógeno ou à epidemiologia da doença. Este trabalho visou estudar o crescimento micelial e a produção de conídios de isolados de C. perennans em meios de cultura com e sem fungicidas e determinar o efeito de temperaturas e períodos de umidade na infecção de maçãs Fuji . As ações conduzidas foram: a) determinação os efeitos dos meios de cultura batata-dextrose-ágar (BDA), ágar-extrato-de-malte (AEM) e ágar-sucoV8 (V8) no crescimento micelial e produção de conídios de nove isolados de C. perennans; b) avaliação a sensibilidade in vitro de C. perennans a seis concentrações dos fungicidas captan, hidróxido de cobre, dithianon, mancozeb e trifloxistrobin incorporados ao meio de cultura BDA; c) avaliação da incidência e severidade da podridão olho-de-boi em maçãs Fuji inoculadas com C. perennans e submetidas a diferentes combinações de períodos de umidade e temperatura. Os resultados mostraram que o maior estímulo ao crescimento do micélio do patógeno foi induzido pelos meios de cultura AEM e V8 e que cinco dos nove isolados avaliados produziram maior quantidade de conídios quando cultivados em suco V8 e quatro em AEM. Todos os fungicidas apresentaram-se eficientes para o controle do crescimento micelial de C. perennans quando comparados a testemunha, porém os resultados mais promissores foram obtidos com os fungicidas dithianon e mancozeb. A temperatura e período de incubação que proporcionaram maior índice de incidência e severidade da podridão olho-de-boi em frutos de maçã cv. Fuji, foram de 22°C com 20 horas de incubação

In this thesis, optimization of production of lipolytic enzymes by submerzed cultivation of Bacillus subtilis (BS) was studied. Production of lipolytic enzymes was tested in three nutrient media, which differed mainly in main sources of carbon, respectively of nitrogen. The first medium contained mainly extract from calf brain and beef heart (BHIB), the second medium contained peptone and yeast extract (NB) and the third one contained peptone and yeast extract with the addition of 2% (w/v) glucose (NBG). The highest lipolytic activity (0.0784 Uml-1) was measured in NBG medium. Maximum of lipolytic activity was observed before the end of the exponential phase of BS growth in all the media. Temperature optimum in NBG medium was determined from 30 to 50 °C, pH optimum in the range of 5 to 11 and subsequently the temperature stability of lipolytic enzymes produced by the BS was estimated. The activity value was determined spectrometrically using p-nitrophenyllaurate as a substrate. Produced lipolytic enzymes showed maximum activity at 37 °C in the alkaline pH of 8.0. Measurement of temperature stability showed that lipolytic enzymes are relatively thermostable enzymes retaining 100 % of the activity even after 1 hour of cultivation at 30 - 50 °C. The presence of 1% (w/v) olive oil in medium NBG caused a decrease in lipolytic activity by 65 % as well as in pH from 6.5 to 5.4 after 14 days of cultivation. After substitution of glucose by fructose in medium NBG, lipolytic activity showed comparable values during the first week of cultivation. On the other hand, the decrease of lipolytic activity by 29 % in the medium with fructose was observed after 14 days of cultivation. A procedure for the identification of lipolytic enzymes of BS by peptide massfingerprinting was developed to understand the potential of synthetic polyester - poly(e-caprolactone) as a lipase inductor. Degradation study of commercial polyester poly(e-caprolactone) was carried out by submerged cultivation of Bacillus subtilis in NBG medium at initial pH 7.0 and 30 °C for 14 days. PCL (Mn = 10,000, Mw = 14 000) was studied in the form of films (1.0 x 1.0 cm), which were prepared by melt-pressing, rapid cooling of the melt to 4 °C and evaporation of the solvent from 2 % dichlormethane solution. The evaluation of the films shown occurrence of weight loss (7.8 - 17.0 wt.%) together with the formation of numerous holes and cracks in the sample surface in relation to the method of the films preparation. Lipolytic activity values increased by 9 - 17 % in the degradation media compared to control samples. Densitometric monitoring showed also higher increase in cell mass in the degradation medium compared with control samples. Based on the results obtained, the degradation process induced by BS could be suggested.