Researchers are frequently faced with the problem of analyzing incomplete and often unbalanced genotype-by-environment (GxE) matrices which arise as a trials programme progresses over seasons. The principal data for this investigation, arising from a ten year programme of onion trials, has less than 2,300 of the 49,200 combinations from the 400 genotypes and 123 environments. This 'sparsity' renders standard GxE methodology inapplicable. Analysis of this data to identify onion varieties that suit the shorter, hotter days of tropical and subtropical locations therefore presented a unique challenge. Removal of some data to form a complete GxE matrix wastes information and is consequently undesirable. An incomplete GxE matrix can be analyzed using the additive main effects and multiplicative interaction (AMMI) model in conjunction with the EM algorithm but proved unsatisfactory in this instance. Cluster analysis has been commonly used in GxE analyses, but current methods are inadequate when the data matrix is incomplete. If clustering is to be applied to incomplete data sets, one of two routes needs to be taken: either the clustering procedure must be modified to handle the missing data, or the missing entries must be imputed so that standard cluster analysis can be performed. A new clustering method capable of handling incomplete data has been developed. 'Two-stage clustering', as it has been named, relies on a partitioning of squared Euclidean distance into two independent components, the GxE interaction and the genotype main effect. These components are used in the first and second stages of clustering respectively. Two-stage clustering forms the basis for imputing missing values in a GxE matrix, so that a more complete data array is available for other GxE analyses. 'Two-stage imputation' estimates unobserved GxE yields using inter-genotype similarities to adjust observed yield data in the environment in which the yield is missing. This new imputation method is transferrable to any two-way data situation where all observations are measured on the same scale and the two factors are expected to have significant interaction. This simple, but effective, imputation method is shown to improve on an existing method that confounds the GxE interaction and the genotype main effect. Future development of two-stage imputation will use a parameterization of two-stage clustering in a multiple imputation process. Varieties recommended for use in a certain environment would normally be chosen using results from similar environments. Differing cluster analysis approaches were applied, but led to inconsistent environment clusterings. A graphical summary tool, created to ease the difficulty in identifying the differences between pairs of clusterings, proved especially useful when the number of clusters and clustered observations were high. 'Cluster influence diagrams' were also used to investigate the effects the new imputation method had on the qualitative structure of the data. A consequence of the principal data's sparsity was that imputed values were found to be dependent on the existence of observable inter-genotype relationships, rather than the strength of these observable relationships. As a result of this investigation, practical recommendations are provided for limiting the detrimental effects of sparsity. Applying these recommendations will enhance the future ability of two-stage imputation to identify those onion varieties that suit tropical and subtropical locations.

Made available in DSpace on 2015-03-26T13:39:50Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2026341 bytes, checksum: 828dbf83609308213dde6a386c60d67f (MD5) Previous issue date: 2012-06-08 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Aiming to assess the conservation of onion bulbs, "Bola Precoce" variety, using air treatment unit (ATU), known as heat pump, as an alternative method of drying, an experiment was carried out in two consecutive years (2010 and 2011) at the Federal University of Viçosa, Viçosa City, Minas Gerais State, Brazil. The bulbs were cured in silos with capacity of 500 kg. The treatments consisted of T1 (aeration using air at room temperature), T2 (aeration using hot and dehydrated air), T3 (aeration using air heated by burning propane), and T4 (witness, bulbs cured with ambient air). Relative water content of the peel and internal film, the peel and pulp color, visual index of overcoming dormancy, total soluble sugars, reducing sugars, non-reducing sugars, dry matter content, soluble solids, total titratable acidity, alliinase activity, soluble phenolic content, weight loss, and percentage of damaged bulbs, sprouted and rooted were evaluated at the end of 14 days of storage. In 2010, during curing, the relative water content of the pulp was reduced in treatments with hot and dehydrated air and with heated air by burning propane. The bulbs cured with hot and dehydrated air had more intense yellow pulp. The bulbs cured with air heated by burning propane showed high concentrations of total soluble sugars, reducing sugars, and soluble solids, probably due to high temperature of this treatment. For concentration of pyruvic acid, the lowest values were observed in the T2 and T3 bulbs. High air temperature in these treatments probably has inhibited the activity of alliinase. During storage, the concentration of pyruvic acid was higher with hot and dehydrated air. The largest loss of relative weight was observed on the first layers of the treatment with hot and dehydrated air and treatment with heated air by burning propane. Bulbs of T2 showed a yellow and clear peel when compared with the bulbs of the witness. Treatments with hot and dehydrated air and heated air by burning propane showed higher levels of total soluble sugars and reducing sugars. At the end of storage, bulbs sprouted and rooted were not observed, but the witness had a higher percentage of damaged bulbs and high visual index of overcoming dormancy. In 2011, the cure of treatment was completed at different times, 12, 27, 48, and 168 hours for T1, T2, T3, and T4, respectively. Bulbs of the witness showed the highest average values for the relative water content of peel, and bulbs cured with hot and dehydrated air had the highest average values for the relative water content of the film inside. The onion bulbs of T2 (hot and dehydrated air) showed intense yellow pulp at the end of the cure process. The conclusion of this work is that, regardless of the used cure method, the quality characteristics of onion bulbs post-harvest were preserved. However, T2 (aeration using heated and dehydrated air) allowed the onion bulbs were cured in a shorter time (12 hours). And besides, this treatment allowed obtaining an intense yellow color for the onion bulbs pulp. / Com o objetivo de avaliar a conservação dos bulbos de cebola da variedade Bola Precoce , utilizando uma unidade de tratamento de ar (UTA), conhecida como bomba de calor, como método alternativo de secagem, foi conduzido, em dois anos consecutivos (2010 e 2011), um experimento na Universidade Federal de Viçosa. Os bulbos foram curados em silos com capacidade de 500 kg. Os tratamentos consistiram em: T1 (aeração utilizando ar a temperatura ambiente), T2 (aeração utilizando ar quente e desidratado), T3 (aeração utilizando ar aquecido pela queima de propano) e T4 (Testemunha, bulbos curados com ar ambiente). Avaliou-se o teor relativo de água da casca e películas internas, coloração da casca e polpa, índice visual de superação da dormência, açúcares solúveis totais, açúcares redutores, açúcares não redutores, teor de massa seca, sólidos solúveis, acidez total titulável, atividade da alinase, teor de compostos fenólicos solúveis,perda de massa fresca e percentagem de bulbos deteriorados, brotados e enraizados no final de 14 dias de armazenamento. Em 2010, durante a cura, oteor relativo de água da polpa foi menor nos tratamentos com ar quente e desidratado e com ar aquecido pela queima de propano. Os bulbos curados com ar quentee desidratado apresentaram a polpa amarelo mais intenso. Os bulbos curados com ar aquecido pela queima de propano apresentaram maiores concentrações de açúcares solúveis totais, açúcares redutores e sólidos solúveis, devido, provavelmente, a maior temperatura deste tratamento. Para a concentração de ácido pirúvico, os menores valores foram observados nos bulbos dos T2 e T3. A maior temperatura do ar nesses tratamentos, provavelmente, inibiu a atividade da alinase. Durante o armazenamento,aconcentração de ácido pirúvico foi maior no tratamento com ar quente e desidratado. As maiores perdas de massa fresca relativa foram observadas nas primeiras camadas do tratamento com ar quente e desidratadoe no tratamento com ar aquecido pela queima de propano. Os bulbos do T2 apresentaram a casca amarela e clara quando comparado com os bulbos da testemunha. Os tratamentos com ar quente e desidratado e ar aquecido pela queima de propano apresentaram maiores teores de açúcares solúveis totais e açúcares redutores. No final do armazenamento, não foram observados bulbos brotados e enraizados, porém a testemunha apresentou maior porcentagem de bulbos deteriorados e maior índice visual de superação da dormência. No ano de 2011, a cura dos tratamentos foi finalizada em tempos diferentes, 12, 27, 48 e 168 horas para T1, T2, T3 e T4 respectivamente.Os bulbos da testemunha apresentaram os maiores valores médios para o teor relativo de água da casca e os bulbos curados com ar quente e desidratado apresentaram os maiores valores médios para o teor relativo de água da película interna. Os bulbos de cebola do T2 (ar quente e desidratado) apresentaram a polpa amarelo intenso no final do processo de cura. Conclui-se com este trabalho que, independente do método de cura utilizado, as características de qualidade pós-colheita dos bulbos de cebola foram preservadas. No entanto, o T2 (aeração utilizando ar aquecido e desidratado) permitiu que os bulbos de cebola fossem curados num menor período de tempo (12 horas). E, além disso, este tratamento permitiu a obtenção de uma coloração da polpa dos bulbos amarelo intenso.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-09-19T13:59:13Z No. of bitstreams: 1 Antonio Esmael Silva de Oliveira.pdf: 1089311 bytes, checksum: e93b02f0fa36f0951963b3bf1afdc9e9 (MD5) / Made available in DSpace on 2016-09-19T13:59:13Z (GMT). No. of bitstreams: 1 Antonio Esmael Silva de Oliveira.pdf: 1089311 bytes, checksum: e93b02f0fa36f0951963b3bf1afdc9e9 (MD5) Previous issue date: 2015-09-18 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / In the present work were estimated genetic gains in two environments due to recurrent selection practiced in population CNPH6400 for the type Valenciano, as well as parameters of adaptability and stability in five environments, with the final objective to evaluate the potential for recommendation of Valencian populations for the Sao Francisco Valley. The experiments were carried out in the municipalities of Petrolina - PE, Juazeiro - BA, and Belem San Francisco - PE, during the years 2013 to 2014. It was adopted the experimental design of randomized blocks, with three replications and twelve treatments to evaluate the genetic gain and fourteen treatments, including eight Valencianas for adaptability and stability parameters. The characteristics evaluated were total and commercial bulb yields, which were. Adjusted by covariance from the average plant stand of each experiment. Were estimated heritability, differential selection, genetic gain. Adaptability and stability parameters were estimated by the methods of Eberhart & Russel and Lin & Binns. Significant differences were observed for bulbs commercial production in the two environment, except for the population 25CA10 in Juazeiro - BA. The mean genetic gain for bulbs commercial production in the yellow Valenciana population 25CA10 were 378.88% in Petrolina - PE and 16.30% in Juazeiro - BA, while the purple population T811CR13 the gains were 340.76% to Petrolina - PE and 55 01% to Juazeiro - BA. The genetic gains were not linear to the sequence of the evaluated cycles, and these oscillations were attributed to genetic drift and selection emphasizing the thickness of cataphylls in recent cycles. It was observed genotype x environment interaction for all variables. The two methodologies presented discrepant results for the cultivar Alfa San Francisco. The Valencianas 25CA10 populations and T811CR13 showed average bulb productions close or above experiments means, combined with wide adaptability and stability, having the potential to be recommended as new cultivars for the region of the São Francisco Valley. / No presente trabalho foram estimados ganhos genéticos em dois ambientes devido a seleção recorrente praticada na população CNPH6400 para o tipo Valenciano, bem como parâmetros de adaptabilidade e estabilidade em cinco ambientes, com o objetivo final de avaliar o potencial de recomendação de populações Valencianas para o Vale do São Francisco. Os experimentos foram conduzidos nos municípios de Petrolina – PE, Juazeiro – BA, e Belém do São Francisco – PE, nos anos de 2013 a 2014. Foi adotado o delineamento experimental de blocos ao acaso, com três repetições, sendo doze tratamentos para avaliação do ganho genético e quatorze tratamentos, sendo oito Valencianas para parâmetros de adaptabilidade e estabilidade. As características avaliadas foram produção total de bulbos e produção de bulbos comerciais. Os dados da produção total foram corrigidos pela covariância a partir do stand médio de cada experimento. Foram estimadas a herdabilidade, o diferencial de seleção, o ganho genético. Parâmetros de adaptabilidade e estabilidade foram estimadas pelas metodologias de Eberhart & Russel e Lin & Binns. Nas avaliações de ganho genético foram observadas diferenças significativas para produção comercial de bulbos nos dois ambientes, exceto para a população 25CA10 em Juazeiro - BA. As médias do ganho genético para produção comercial na população Valenciana amarela 25CA10 foram 378,88% em Petrolina – PE e 16,30% em Juazeiro – BA, enquanto na população roxa T811CR13 os ganhos foram de 340,76% para Petrolina – PE e 55,01% de Juazeiro – BA. Os ganhos genéticos não foram lineares para a sequência dos ciclos avaliados, sendo essa oscilação atribuída a deriva genética e a seleção com ênfase a espessura de catáfilos nos últimos ciclos. Foi observada interação genótipo x ambiente para todas as variáveis avaliadas. As duas metodologias apresentaram resultados discrepantes para a cultivar Alfa São Francisco. As populações Valencianas 25CA10 e T811CR13 apresentaram produção de bulbos próximos ou acima das médias dos experimentos, aliadas a ampla adaptabilidade e boa estabilidade, tendo potencial para serem recomendadas como novas cultivares para a região do Vale do São Francisco.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-11-28T12:42:51Z No. of bitstreams: 1 Walkiria Alves da Silva.pdf: 874748 bytes, checksum: 5da61c26a69ee185c1ff223877497242 (MD5) / Made available in DSpace on 2016-11-28T12:42:51Z (GMT). No. of bitstreams: 1 Walkiria Alves da Silva.pdf: 874748 bytes, checksum: 5da61c26a69ee185c1ff223877497242 (MD5) Previous issue date: 2016-07-29 / The onion is the third vegetable in economic importance on the world, with emphasis on Brazil as one of the most economically important vegetable, both by the volume and the income produced. This culture can be affected by various diseases, especially the scale rot, caused by bacteria of the Burkholderia cepacia complex. In an attempt to determine the favorable conditions for the development of epidemics, the knowledge of host-pathogen-environment interaction is essential. Thus, the appropriate inoculum concentration, the temperature range, the period of humidification exposure and the age, which the plant host becomes more susceptible to the establishment of high levels of disease, should be identified for each host-pathogen association. Although these epidemiological characteristics are the key factors for infection and subsequent development of rot in scale, there is no consistent information about the influence of these parameters on the behavior of the disease. Therefore, this study aimed to select and identify six isolates of B. cepacia complex, and determine the in vitro temperature, evaluate the effect of the inoculum concentration, temperature, presence and exposure to moisture chamber and the age of the bulbs in the severity of scale rot onion. Through Bayesian inference, the isolates CRMB31, and CRMB109 CRMB259 were identified as B. cenocepacia, while the isolates CRMB76, and CRMB199 CRMB222 were identified as B. arboris. The optimum temperature for in vitro growth of the isolates B. cenocepacia was 30°C, while for the isolates of B. arboris was 28°C. The conditions that predispose the occurrence of rot severity scale at higher inoculum were load of 108 CFU/mL, together on a wetness of 48 h, temperature between 35 and 40°C and more young tissues. To our knowledge, this is the first study to determine the environmental factors favorable to the development of rot in onion scale. In addition, the information obtained in this study will be useful for understanding the epidemics of the rot in scale and will assist in the implementation of strategies to control the disease. / A cebola é a terceira hortaliça em importância econômica no mundo, tendo destaque no Brasil como uma das hortaliças economicamente mais importantes, tanto pelo volume produzido como pela renda gerada. Esta cultura pode ser acometida por várias doenças, destacando-se a podridão em escama causada por bactérias do complexo Burkholderia cepacia. Na tentativa de determinar as condições favoráveis ao desenvolvimento de epidemias, o conhecimento da interação patógeno-hospedeiro-ambiente é imprescindível. Assim sendo, a concentração de inóculo adequada, a faixa de temperatura, o período de exposição à umidificação e a idade em que a planta hospedeira se torna mais suscetível para o estabelecimento de altos níveis de doença devem ser definidos para cada associação patógeno-hospedeiro. Embora essas características epidemiológicas sejam fatores primordiais para infecção e posterior desenvolvimento da podridão em escama, não existem informações consistentes a respeito da influência desses parâmetros sobre o comportamento da doença. Portanto, o presente trabalho teve como objetivos selecionar e identificar seis isolados do complexo B. cepacia e determinar a temperatura in vitro, avaliar o efeito da concentração de inóculo, temperatura, presença e tempo de exposição à câmara úmida e idade dos bulbos na severidade da podridão em escama da cebola. Por meio de Inferência Bayesiana, os isolados CRMB31, CRMB109 e CRMB259 foram identificados como B. cenocepacia, enquanto os isolados CRMB76, CRMB199 e CRMB222 foram identificados como B. arboris. A temperatura ideal de crescimento in vitro para os isolados de B. cenocepacia foi de 30°C, enquanto para os isolados de B. arboris foi de 28°C. As condições que predispuseram a ocorrência de severidade da podridão em escama mais elevadas foram carga de inóculo de 108 UFC/mL, em conjunto com um período de molhamento de 48 h, temperaturas entre 35 e 40°C e tecidos mais novos. Para o nosso conhecimento, este é o primeiro estudo realizado para determinação dos fatores ambientais favoráveis ao desenvolvimento da podridão em escama da cebola. Além disso, as informações obtidas neste estudo serão úteis para o entendimento de epidemias da podridão em escama e auxiliarão a implementação de estratégias para o controle da doença.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-12-02T12:42:24Z No. of bitstreams: 1 Willams Jose de Oliveira.pdf: 1187273 bytes, checksum: 3d0f4978c0a4ad8c65c3b398bf1ec2aa (MD5) / Made available in DSpace on 2016-12-02T12:42:24Z (GMT). No. of bitstreams: 1 Willams Jose de Oliveira.pdf: 1187273 bytes, checksum: 3d0f4978c0a4ad8c65c3b398bf1ec2aa (MD5) Previous issue date: 2015-02-19 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / It was produced approximately 1,601,767 tons of onions in the 2014 harvest in Brazil, and the northeastern region with approximately 23% of this production. The culture of the onion can be affected by various diseases, among them are the bacterial rot. Between the types of decay occurring in onion bulbs stands out the scales rot because it causes significant losses in Brazil. This disease is associated with bacteria from the Burkholderia cepacea complex, Burkholderia gladioli pv. alliicola, Pseudomonas aeruginosa and Serratia marcescens. Given that for the application of efficient management measures it is necessary to understand the etiology of the disease and that it is not known for sure what the genera and species that are associated with the rot of onion scales in the semi-arid northeast, the present study have the following objectives: i) identify the bacteria involved with the disease in this region by sequencing and phylogenetic analysis of 16S rRNA region, ii) evaluate the behavior relatedness of the species identified by rep-PCR, and iii) evaluate the pathological behavior of different species identified. For this purpose, samples were taken in the main producing regions of onion in Pernambuco and Bahia semi-arid region, followed by the isolation and storage of strains in Culture Collection Rosa Mariano (CRM) of the Phytobacteriology Laboratory at the Federal Rural University of Pernambuco. We obtained 45 strains which were grouped into three clades: clade I, containing strains identified as B. cepacia complex (n = 29), clade II containing strains identified as B. gladioli (n = 10) and clade III containing strains identified as P. aeruginosa (n = 6). These strains were submitted to analysis of rep-PCR and were separated into 31 groups with level 70% of similarity. However, it was not possible to identify these three clades by this technique. When artificially inoculated in onion scales, strains of B. cepacia complex and B. gladioli were significantly more aggressive than P. aeruginosa strains. Based on phylogenetic identification performed in this study, it is concluded that the rot of onion bulb scales in the Brazilian semi-arid northeast is caused by the strains of B. cepacia complex, B. gladioli e P. aeruginosa. Moreover, more than one species of the B. cepacia complex may be associated with rot scales in this region. / O Brasil produziu aproximadamente 1.601.767 toneladas de cebola na safra de 2014, sendo a região nordeste responsável por 23% dessa produção. A cultura da cebola pode ser acometida por diversas doenças, destacando-se as podridões bacterianas. Dentre os tipos de podridões que ocorrem em bulbos de cebola destaca-se a podridão de escamas, a qual pode causar perdas de até 50% no Brasil. Essa doença está associada a bactrérias do complexo Burkholderia cepacea, Burkholderia gladioli pv. alliicola, Pseudomonas aeruginosa e Serratia marcescens. Visto que para aplicação de medidas de manejo eficientes faz-se necessário o conhecimento da etiologia da doença e que ainda não se sabe ao certo quais são os gêneros e espécies que estão associadas à podridão de escamas da cebola no semiárido nordestino, o presente estudo teve como objetivos: i) identificar as bactérias envolvidas com a doença nessa região por meio de sequenciamento e análise filogenética da região 16S rRNA, ii) avaliar o comportamento genético das espécies identificadas por meio de rep-PCR, e iii) avaliar o comportamento patológico das diferentes espécies identificadas. Para isto foram realizadas coletas nas principais regiões produtoras de cebola do semiárido Pernambucano e Baiano, seguindo-se o isolamento e depósito dos isolados na Coleção de Culturas Rosa Mariano (CRM) do Laboratório de Fitobacteriologia da Universidade Federal Rural de Pernambuco. Foram obtidos 45 isolados, os quais foram agrupados em três clados: clado I, contendo isolados identificados como sendo do complexo B. cepacia (n= 29), clado II, contendo isolados de identificados como B. gladioli (n=10) e clado III, contendo isolados identificados como P. aeruginosa (n=6). Esses isolados foram submetidos a análises de rep-PCR, sendo separados em 31 grupos ao nível de 70 % de similaridade. No entanto, não foi possível identificar esses três clados por meio desta técnica. Quando artificialmente inoculados em escamas de cebola, os isolados do complexo B. cepacia e de B. gladioli foram significativamente mais agressivos do que os isolados de P. aeruginosa. Com base na identificação filogenética realizada no presente estudo, conclui-se que a podridão de escamas de bulbos de cebola no semiárido nordestino brasileiro é causada por isolados do complexo B. cepacia, B. gladioli e P. aeruginosa. Além disso, mais de uma espécie do complexo B. cepacia pode estar associada à podridão de escamas nessa região.

The predictive values of standard and non-standard germination temperatures, standard accelerated ageing (AA) and saturated salt accelerated ageing (SSAA) tests were investigated. Germination tests were performed at standard and non-standard temperatures of 10°, 20°, 20°/30° and 30°C for cabbage and tomato, and 10°, 15°, 20° and 30°C for onion. The AA and SSAA tests were conducted using four relative humidities: standard AA (RH100), NaCl (RH75), Ca(NO3)2 (RH43) and MgCl2 (RH32). Emergence trials were also conducted at a range of temperatures (winter, 15°/25° and 30°C) and media (Hygromix and soil) using seedling trays. Correlations were calculated to evaluate the relationship between laboratory and emergence test results. Three onion seed lots that have different vigour levels were primed with PEG or NaCl and were germinated and planted under varying temperatures and levels of salinity. There were vigour differences among different seed lots of cabbage, onion and tomato seeds used in this study. Using the different laboratory tests, seed lots were distinguished as high, medium and low vigour seed lots. The low temperature germination test (10°C) for cabbage and onion; and 20°C for tomato were found to be effective for separation of seed lots according to their vigour levels. All SSAA vigour tests were also useful in differentiating seed lots based on their physiological stage of deterioration. Using the standard AA (RH100) the seed moisture content was high (29 to 45%), resulting in fungal growth. However, in the SSAA test the moisture content was below 14% and no fungal growth was observed. Ageing of seed lots using NaCl and MgCl2 resulted in a low narrow range of moisture contents, but using Ca (NO3)2 the range of the moisture content between seed lots was higher. For all crop seeds, there was no significant difference in the percentage emergence between the two growth media but larger seedlings were observed from the commercial growth medium (Hygromix). For cabbage, highly significant correlations were obtained between germination percentage at 10°C and RH32 and all emergence trials. In onion, the correlations were not consistent; highly significant correlations were observed from germination capacity (GC), 15°C, 20°C, 30°C, RH75 and RH32; and emergence parameters at specific conditions. However, the germination percentage from 30°C correlated significantly with the final emergence percentage and seedling vigour index. Germination of tomato seeds at 20°C and all SSAA had highly significant correlation with all emergence parameters. The germination rate parameters: MGT (mean germination time) and GI (germination index) were valuable in categorising seed lots with moderate vigour levels, however, except GE in cabbage and onion, all other germination rate characters failed to correlate with any emergence parameters. The radicle percentage germination (viability or GC) and final emergence percentage (FEP) were not enhanced by priming in all seed lots in the germination and emergence trials at all temperatures. The percentage of normal seedling was increased due to priming when seeds were subjected to low temperature and higher salinity levels. Priming was effective in improving the rate, uniformity of germination/emergence; and increased the seedling dry mass of onion seeds when grown under relatively cold environmental conditions. Priming was more beneficial for low vigour seed lots (seed lot A) than for high vigour seed lots (B, C). Priming also improved germination rate and uniformity at all salinity levels, but faster rate of emergence, more uniform and higher seedling dry mass were only observed when seeds were watered with low salinity levels (25 mM of NaCl). No significant difference was observed using NaCl or PEG as priming agent. Onion seeds are tolerant to salinity during germination and the effect of priming was more beneficial at emergence. / Dissertation (MSc (Agric) Horticulture)--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

This diploma thesis analyzes the deep web environment with the use of business models from the surface web. In the indroduction part of the thesis summarize terms web, deep web and dark web, these terms are intermingle the entire thesis, also brings the concept on Onion routing with use of Tor software. An inseparable part is the comparsion of tools which can be used for access to the dark web. The main part of the thesis analyzes most used business models on the surface web including their methods of monetization and after that author tries to apply these models in the dark web environment. An importat part of this work is the analysis a type of services occuring on the dark web and mutual comparison of several sub-criteria of each service. In the final part the thesis presents project Turris on which is applied to create a relay node for the Tor network.

Presented master thesis dealt with the analysis of garlic and onion samples and tried to find correlations between chemical composition and country of origin. The parameters examined were dry content, crude protein content, concentration of phenolic compunds, carbohydrate content (fructose, glucose), alliin content and concentration of selected elements (P, Mg, Ca, Na, K, Fe, Zn). Average content of dry matter of fresh samples was 35,84 ±2,12 g/100 g and of dehydrated samples was 90,61 ±2,90 g/100 g. Concentration of phenolic compounds was measured spectrophotometrically with Folin-Ciocault reagent. Average phenolic compounds content of samples was 0,1840 ±0,1286 GAE g/100 g. Crude protein content was measured by Kjeldahl method, and calculated from total nitrogen content. Carbohydrates were measured by HPLC-ELSD after hydrolysis of fructans. Average content of fructose of garlic samples was 57,014 ±0,863 g/100 g, of onion samples was 33,718 ±1,168 g/100 g. Average content of glucose of onion samples was 22,633 ±0,405 g/100 g. Alliin content was measured by HPLC-DAD method. Average alliin content of fresh samples was 4,644 ±0,446 g/100 g and of dehydrated samples was 1,962 ±0,180 g/100 g. Elemental analysis was conducted by ICP-OES method. Average concentration of selected elements was: P 2,15 ±0,11 mg/g, Mg 0,638 ±0,03 mg/g, Ca 1,246 ±0,05 mg/g, Na 0,550 ±0,08 mg/g, K 7,49 ±0,41 mg/g, Fe 79,3 ±6,16 mg/kg, Zn 11,4 ±3,33 mg/kg. Obtained data were statistically processed on significance level 0,05. Based on the principal components analysis, it was found, that the best parameters to differentiate samples from Czechia, Poland and Ukraine from other countries were content of nitrogen, phosphorus, magnesium, sodium and calcium. It was also discovered, that genus differences between onion and garlic have greater significance than geographical differences.

Background. With increased Internet usage occurring across the world journalists, dissidents and criminals have moved their operations online, and in turn, governments and law enforcement have increased their surveillance of their country’s networks. This has increased the popularity of programs masking users’ identities online such as the Tor Project. By encrypting and routing the traffic through several nodes, the users’ identity is hidden. But how are Tor users utilizing the network, and is any of it in the plain text despite the dangers of it? How has the usage of Tor changed compared to 11 years ago? Objectives. The thesis objective is to analyze captured Tor network traffic that reveals what data is sent through the network. The collected data helps draw conclusions about Tor usage and is compared with previous studies. Methods. Three Tor exit nodes are set up and operated for one week in the US, Germany, and Japan. We deploy packet sniffers performing a deep packet inspection on each traffic flow to identify attributes such as application protocol, number of bytes sent in a flow, and content-type if the traffic was sent in plain text. All stored data is anonymized. Results. The results show that 100.35 million flows were recorded, with 32.47%of them sending 4 or fewer packets in total. The most used application protocol was TLS with 55.03% of total traffic. The HTTP usage was 15.91% and 16% was unknown protocol(s). The countries receiving the most traffic were the US with over45% of all traffic, followed by the Netherlands, UK, and Germany with less than 10%of recorded traffic as its destination. The most frequently used destination ports were 443 at 49.5%, 5222 at 12.7%, 80 with 11.9%, and 25 at 9.3%.Conclusions. The experiment shows that it is possible to perform traffic analysis on the Tor network and acquire significant data. It shows that the Tor network is widely used in the world but with the US and Europe accounting for most of the traffic. As expected there has been a shift from HTTP to HTTPS traffic when compared to previous research. However, there is still unencrypted traffic on the network, where some of the traffic could be explained by automated tools like web crawlers. Tor users need to increase their awareness in what traffic they are sending through the network, as a user with malicious intent can perform the same experiment and potentially acquire unencrypted sensitive data.

Two field experiments were carried out. In the first experiment, 13 variables were studied for 3 inbred groups as influenced by genetic differences, source of pollen, soil moisture, fertilizers , and size of bulbs. Path-coefficient analysis was made of var ious insect pollinators influencing seed yield in different inbreds, and of components of seed production in all inbreds together. In the second experiment, 4 variables were studied for one male-sterile inbred and one male-fertile inbred as influenced by soil moisture and fertilizers. Genetic differences among inbreds were the most important source of variation in seed yields. This points out that a major portion of the onion seed problem could be solved through plant breeding. The inbreds differed very significantly in t heir attractiveness to pollinating insects, probably as a result of varying genetic vigor which influenced nectar formation. Most of the inbreds had negative correlation or no correlation between the number of honey bee nectar collectors and seed yield. The separation of correlation with honey bee nectar and pollen collectors into components of direct and indirect effects indicates that the number of pollinating insects was excessive for all inbreds in the experiment. Negative direct effects on seed yield and negative indirect effects through percent fertilized flowers and seeds per fertilized flower disclose some important aspects as possible causes for low onion seed yields: 1. Depletion of assimilated food needed for the development of fertilized ovules through an overdraw on nectar by nectar collectors. 2. Water deficit affecting fertilized developing ovules due to increased transpiration resulting from overhandling of flowers by honey bees, especially by pollen collectors, which through nervous search for pollen on male- sterile lines might cause enough physical damage to increase transpiration even at low visitation levels. At high visitation levels, pollen collectors might also harm male-fertile lines. 3 . Removal of pollen from the stigmas of male-sterile flowers by high populations of pollen collecting honey bees. Compatibility of the pollen parents with the male-sterile inbreds was influenced by soil moisture levels. At high moisture, M611C increased seed yields while B12115-2C decreased them. At low moisture the reverse was true. In the first experiment there was no significant yield response to varying soil moisture levels due to contrasting effects of high soil moisture on compatibility with pollen parents. In the second experiment, the pollen parent B2215C was used and a significant favorable response to high soil moisture was obtained. Salinity aspects and the effects of indiscriminate use of fertilizers were tested through the method of fertilizer placement. While fertilizers reduced seed yield , high soil moisture tended to reduce the negative effects of nitrogen and to produce favorable response to phosphorus. Seed yield followed the trend in plant survival as affected by the induced salinity x moisture relationships. The size of bulbs had a great influence on seed yields, mainly through an increased number of umbels per plant. It seems that the number of umbels per plant had more influence on the number of flowers per row than did the number of flowers per umbel. Path-coefficient analysis of components of onion seed production indicates that the percentage of fertilized flowers is the most important criterion for selection to improve seed yield. It would be ideal to combine both high percentage of fertilized flowers and large number of flowers per umbel, but if compromise has to be made, selection would best be considered on the basis of greater percentage of fertilized flowers in the umbel. Plants which have a large percentage of fertilized flowers can be easily detected at the pre-seed harvest stage.