The Texas Blackland Prairie is one of the most productive agricultural regions in Texas. This region provides a long growing season coupled with soils that have a high water holding capacity. However, the soils also provide significant challenges to producers because the high water holding capacity is a product of a high clay percentage. This research was aimed to develop and test an expert-based trafficabililty index, based upon soil moisture, for planting cotton (Gossypium hirsutum L.) and corn (Zea mays L.) on the Texas Blackland Prairie. Testing the index focused on quantify the potential effect of high soil moisture at planting on seed furrow sidewall compaction and associated plant growth response. Once the trafficability index was developed, three workable soil moisture regimes were recreated in no-tillage and conventional tillage plots at the Stiles Farm Foundation in Thrall, Texas. The index nomenclature included: "Dry-Workable", "Optimal" and "Wet-Workable". After planting corn and cotton into conventional and no tillage plots, 0.45 x 0.20 x 0.15 m intact soil blocks were removed from each plot and kept in a controlled environment. At 28 days, each block was destructively harvested to quantify plant root and shoot growth responses. Each of the three soil moisture indexes was replicated thrice per crop, and the whole experiment was replicated twice in time, n = 48 blocks. The trafficability index was created using three producer experts, and over 10 interviews to collect a range in soil moisture samples. From "Wet Workable" to "Dry Workable", the gravimetric soil moistures were 0.17, 0.22, and 0.26 g g-1. For corn and cotton, a positive relationship between plant growth factors and planting at soil moisture existed. Plants planted at the highest soil moisture emerged faster and developed more root and shoot biomass than those planted at the lowest soil moisture. No evidence of a detrimental plant response because of seed furrow, sidewall compaction from planting at too high a soil moisture content could be quantified. Furthermore, the cotton plants in no-tillage performed better than in conventional tillage, but corn performed better in conventional tillage. Because the results showed an advantage to plant growth by planting in the "Wet Workable" index, the tillage practice that allows the producer to enter the field with a planter at higher moisture contents appears to have an advantage.

Open Access Article

Thalassia testudinum Banks and Solander ex König is the dominant seagrass in the Gulf of Mexico, Caribbean and the West Coast of Florida, yet little rhizome elongation, new short shoot production, or new rhizome meristem production data has been collected via direct measurement. A study of the rhizome growth of T. testudinum was completed in December 2004 in southern Tampa Bay that determined growth after 26.5 months. Two PVC planting frames each containing four rhizomes with 2 short shoots, two rhizomes with 4 short shoots, and two rhizomes with 8 short shoots were planted next to existing T. testudinum beds at 5 sites (n = 10 planting frames). The rhizome apical meristem was removed from half of each set of short shoot units on each planting frame. Plants initially lacking a rhizome meristem produced more new long shoot meristems than those planted with an intact meristem, and larger planting units produced more new rhizome meristems than smaller ones, P = 0.001 and P < 0.001, respectively. The total number of rhizome meristems per planting unit (new meristems + initial meristem) was greater in plantings initially lacking a long shoot meristem in the 2, 4 and 8 short shoot size classes. Only the two short shoot plants benefited from an intact rhizome meristem at planting time, elongating 66.4 cm versus 60.4 cm for plants initially lacking a rhizome meristem at 26.5 months. In the 4 and 8 short shoot classes, plants that lacked a rhizome meristem at planting outpaced those with a meristem, producing 192.1 and 277.9 for 4 and 8 short shoot plants compared to 120.9 cm and 177.7 cm for plants with a meristem during the same time period. The greatest growth rate increases were due to lateral branching on planting units that lacked a rhizome meristem in the two largest size classes (4 and 8 short shoots); the differences between plants with an intact rhizome meristem and those without with the size classes pooled did not prove to be statistically different, P = 0.112. Differences among the size classes were significant, however, P < 0.001. Analysis of new short shoots was analogous to the results for rhizome elongation, with the presence of an initial rhizome factor proving insignificant, P = 0.401, and the initial number of short shoots factor proving significant, P < 0.001. The rhizome growth, new short shoot production, and new rhizome meristem production data determined by direct measurements in this study appear to be the first planting unit measurements for this species under natural conditions.

Although cottonseed is an important source of oil and fiber, the development of cotton embryos has not been investigated as well as development of cotton fiber. The development of cotton embryos in late heart-stage and early cotyledonary stage is less well investigated than the first 10-14 days after anthesis, or the late stages of embryo development during seed-fill and desiccation. This analysis focused on cotton embryos in the late heart-stage and early cotyledonary stage of development (1.5-4.0 mm or about 13-18 DPA). In vitro analyses are important tools for studying embryos in isolation from the endosperm and fiber and when it is necessary to monitor the developing embryo continuously. The original goal of this work was to develop an in vitro culture method that would support continued development of excised zygotic embryos from the early cotyledonary stage into complete plants with true shoots, i.e. true leaves or visible buds and then to use this method to study aspects of developmental regulation during cotyledonary stage and the transition to later stages. Not all embryos were competent to develop true shoots (an apical bud or a leaf plus a bud) in culture. A number of cultural variables were tested and eliminated. Embryo maturity at the time embryos were excised and the presence or absence of light during the first 14 days of culture affected the competence of immature embryos to developed true shoots. The effect of light was verified in several large replicated experiments. Morphological changes occurring during in vivo development were examined microscopically. The transition from heart-stage to early cotyledonary stage and the development of the first leaf from initials to a large structure were identified. Embryonic shoot apices continued to grow in cultured 1-3 mm embryos. The size and shape of light-treated and dark-treated embryonic apices was compared. A germination test of mature seeds identified seedlings with a similar phenotype occurring at similar rates in seedlings and light-cultured embryos and possible causes were discussed.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2003. / Thesis documentation sheet inserted. Appendix reprints five papers and manuscripts co-authored with others. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix.

Branching is a highly plastic trait, enabling plants to adapt their growth form in response to environmental stimuli. In flowering plants, shoot branching is regulated through the activity of axillary buds, which grow into branches. Several classes of plant hormones have been shown to play pivotal roles in regulating bud outgrowth. Auxin derived from the primary shoot apex and active branches inhibits bud outgrowth, whereas cytokinin promotes it. Strigolactones also inhibit bud outgrowth, by changing properties of the auxin transport network, increasing the competition between buds. This occurs by modulating access to the polar auxin transport stream (PATS) in the main stem. The PATS provides directional, long distance transport of auxin down the stem, involving basal localisation of the auxin transporter PIN-FORMED1 (PIN1). Buds need to export their auxin across the stem towards the PATS in order to activate, but since PIN1 is mainly expressed in narrow files of cells associated with the stem vasculature, PIN1 itself it is unlikely to facilitate this connectivity. This thesis re-examines the role of auxin transport in the stem, showing that, besides the PIN1-mediated PATS, other auxin transport proteins constitute a more widespread and less polar auxin transport stream, allowing auxin exchange between the PATS and surrounding tissues. Disruption of this transport stream is shown to reduce bud-bud communication and to partially rescue the increased branching observed in strigolactone mutants. Furthermore, it is shown that distinct classes of auxin transport proteins within this stream can differentially affect bud outgrowth mediated by BRANCHED1 (BRC1). BRC1 is a transcription factor proposed to determine bud activation potential. Taken together, the data presented here provide a more comprehensive understanding of the shoot auxin transport network and its role in shoot branching regulation.

Magister Artium - MA / The controversial singing of the Shoot the Boer song by Julius Malema was a focus of media attention during the period of March 3, 2010 to September 12, 2011.This study aims to analyse the discourses participants draw on in the expression of their positions of race and identity in selected online texts, as well as the different meanings and interpretations the Shoot the Boer song has acquired over time. Using the data drawn from three court rulings, namely the South Gauteng High Court, North Gauteng High Court and the Equality Court and commentaries from various online websites, this project focuses on the various ways in which issues of race are realised through language by focusing on the construction and interpretation of Julius Malema and the Shoot the Boer song within different contextual spaces. This study uses a critical discourse analysis framework, as well as theories of intertextuality, resemiotization, contextand chronotope to analyse the texts which were generated in response to the song. Key findings include the ways in which participants who consider themselves as part of a minority group, construct themselves as 'victims‘ in relation to Malema and the singing of the song. Similarly, another key finding is that the broader discourse of fear exhibited in the various commentaries links to a general fear of 'black power‘ where Malema is a signifier of this 'black power.‘ Overall, the thesis argues that the meanings of the song are multiple and shift with the changing chronotopia of its performance. It therefore support Blommaert‘s (2005) emphasis on the importance of 'text trajectories‘ in establishing the meaning of texts, and argues that the historical meanings associated with the Shoot the Boer song form a complex set of frames on which different participants draw when interpreting the song in 2010.

Made available in DSpace on 2015-03-26T13:42:08Z (GMT). No. of bitstreams: 1 texto completo.pdf: 543911 bytes, checksum: ca6b1ec9421af89b1154b235d7101304 (MD5) Previous issue date: 2008-10-03 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / This study was carried out to develop some protocols for cryopreservation of sugarcane germplasm in liquid nitrogen at -196°C. The exposure time of the shoot tips encapsulated in the laminar flow chamber for obtaining the moisture contents of 30, 20 and 10% was determined in an assay. The results were analyzed and interpreted, by using the free R software. The medium points of each time under evaluation were united by straight line segments, as drawing a tendency line for the moisture loss. Then, with the aid of horizontal lines referring to moisture contents of 30, 20 and 10%, the drying times were directly identified in the graph at 5.7; 7.45 and 10.1 hours, respectively. To induce the tolerance of the shoot tips to drying process, the preculture was accomplished in liquid culture medium enriched with 0.3; 0.5 and 0.75M sucrose for one and two days. The entirely randomized experimental design was used under a factorial scheme 3X2X4 (sucrose concentrations, preculture time and drying time) with three replicates. The survival index data were analyzed and interpreted, by using the free R software. The variance analysis was performed and the averages were compared by the Tukey test at 5% significance, when necessary. According to the results, the following conclusions were drawn: independently of the preculture time to be one or two days, the preculture in the culture medium enriched with 0.3M sucrose was ideal to induce the tolerance of the tissues to drying; the shoot tips were sensitive to the concentration of 0.75M sucrose in the preculture solution. The 12h culture of the shoot tips in the basic culture medium resulted into reactivation of their metabolism through accumulation of the starch grain, besides the recovery of the stress generated by its extraction. The intensity of the starch synthesis was increased, when the shoot tips were precultured in the liquid culture medium containing sucrose at concentrations 0.30; 0.50 and 0.75M. In the cryopreservation of the encapsulated shoot tips, the effect of the sucrose concentration, drying time and defrosting method were studied under a factorial 3X4X3 (three sucrose concentrations, four drying times and three defrosting methods). Independently of the combination adopted when the shoot tips were cryopreserved, a null survival index was obtained. The histological analyses revealed that both cells and cellular walls of the cryopreserved explants were severely damaged. / O objetivo deste trabalho foi o desenvolvimento de protocolos para criopreservação, em nitrogênio líquido a -196°C, de germoplasma de cana-de-açúcar. O tempo de exposição dos ápices caulinares encapsulados a câmara de fluxo laminar para a obtenção dos teores de umidade de 30, 20 e 10% foi determinado através de um ensaio e os resultados obtidos foram analisados e interpretados utilizando o software livre R. Os pontos médios de cada tempo avaliado foram unidos por segmentos de reta traçando uma linha de tendência de perda de umidade. Posteriormente, com o auxílio de linhas horizontais referentes aos teores de umidade de 30, 20 e 10%, os tempos de secagem foram identificados diretamente no gráfico em 5,7; 7,45 e 10,1 horas, respectivamente. Para induzir a tolerância dos ápices caulinares à secagem foi realizado o pré-cultivo em meio de cultura líquido enriquecido com 0,3; 0,5 e 0,75 M de sacarose por um e dois dias. O experimento foi organizado em um esquema fatorial 3X2X4 (concentrações de sacarose, tempo de pré-cultivo e tempo de secagem) segundo o delineamento inteiramente casualizado com três repetições. Os dados do índice de sobrevivência obtidos foram analisados e interpretados utilizando o software livre R. Foi realizada a análise de variância e quando necessário as médias foram comparadas pelo teste de Tukey a 5% de significância. Os resultados indicaram que o pré-cultivo em meio de cultura enriquecido com 0,3 M de sacarose, independentemente se por um ou dois dias, foi ideal para induzir a tolerância dos tecidos à secagem. Os ápices caulinares foram sensíveis à concentração de 0,75 M de sacarose na solução de pré- cultivo. O cultivo por 12 horas dos ápices caulinares em meio básico de cultura resultou além da recuperação do estresse gerado pela sua extração, a reativação do seu metabolismo através do acúmulo de grão de amido. A síntese de amido aumentou em intensidade quando os ápices foram pré- cultivados em meio de cultura líquido contendo sacarose nas concentrações de 0,30; 0,50 e 0,75 M. Na criopreservação dos ápices caulinares encapsulados, estudou-se o efeito de três fatores, concentração de sacarose, tempo de secagem e o método de descongelamento, em um fatorial 3X4X3. Independentemente da combinação adotada quando os ápices caulinares foram criopreservados o índice de sobrevivência obtido foi nulo. As análises histológicas revelaram que as células e a parede celular dos explantes criopreservados foram severamente danificadas.

Orientador: Angelo Pires do Prado / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-15T15:04:17Z (GMT). No. of bitstreams: 1 Gisloti_LauraJane_M.pdf: 851756 bytes, checksum: 02ffdefd182c61c5bec5133a13b29b8f (MD5) Previous issue date: 2009 / Resumo: Este trabalho estabelece alguns aspectos biológicos e ecológicos de Neosilba perezi (Romero & Ruppel, 1973) (Diptera: Lonchaeidae), que ainda constam como desconhecidos na literatura mundial. Dentre as pragas da mandioca, a mosca-dos-brotos, N. perezi,é uma das mais observadas, atacando brotos jovens e ocasionando brotamentos laterais na região atacada. Os trabalhos referentes a essa espécie de lonqueídeo são escassos e os dados a respeito da perda de produção o ocasionada pelo ataque da mosca não são bem estabelecidos. Os objetivos deste trabalho foram caracterizar a infestação por N. perezi no sudoeste do estado de São Paulo correlacionando cada área de estudo, separadamente para cada parâmetro particular de temperatura, precipitação pluviométrica e idade das plantas; avaliar o parasitismo de larvas de N. perezi em dez genótipos de mandioca; conhecer alguns aspectos da interação de parasitoidismo associada larvas de N. perezi; além de caracterizar o desenvolvimento vital do inseto em condições controladas de laboratório e por fim e mostrar os estágios de ovo, larva e adulto. Foram realizadas análises quinzenais em cada área de estudo, no período de março de 2008 a fevereiro de 2009 para obtenção dos índices de parasitismo pelas larvas de N. perezi em brotos de mandioca e os índices de parasitoidismo por braconídeos parasitóides das larvas da mosca. Na análise dos genótipos em relação à infestação por N. perezi, estes foram plantados na área experimental do Departamento de Biologia Vegetal da Universidade de Campinas e assim o índice de infestação foi calculado para cada genótipo, no período de junho de 2008 a janeiro de 2009. O estudo do ciclo de vida da mosca foi realizado através da coleta de ovos em campo, os quais foram mantidos em uma dieta elaborada neste trabalho a qual possibilitou o desenvolvimento total, de ovo a adulto de N. perezi. A dinâmica populacional da mosca-dos-brotos na região estudada está correlacionada, separadamente, com a temperatura, com a pluviosidade e com a idade da plantas, de forma que temperatura acima de 23°C, ou pluviosidade relativamente alta ou ainda idades tardias das plantas afetaram negativamente a população deste inseto. O genótipo "IAC Caapora 105-66" e o genótipo "IAC Cascuda" mostram-se menos suscetíveis à infestação por este inseto enquanto o genótipo "IAC 15" apresentou as maiores porcentagens de infestação. Quanto ao parasitoidismo por braconídeos em larvas de N. perezi, foi constatado que a porcentagem de ataque foi de 24,3% sugerindo que esta interação possa ser um importante fator na dinâmica populacional de N. perezi. Assim, estabelecemos uma descrição sucinta dos aspectos biológicos e ecológicos de N. perezi, que facilitarão estudos subseqüentes relacionados a esta família, além de elucidar alguns aspectos do parasitismo destas larvas em brotos de mandioca que poderão ser usados no esclarecimento de possíveis riscos a cultura desta planta / Abstract: This research establishes some new biological and ecological aspects of Neosilba perezi (Romero & Ruppel, 1973) (Diptera: Lonchaeidae. Among the pests of cassava, the shoot fly, N. perezi, is one of the most studied, attacking young shoots and causing side shoots in the attacked region. The researches related to this of fly are few and the data about production loss caused by the attack of the fly are not well known. The objectives of this research were to characterize infestation by N. perezi in the southwest of the State of São Paulo, Brazil by correlating separately each area, for each particular parameter of temperature, rainfall and the age of plants; evaluate larvae parasitism of N. perezi in ten manioc genotypes; know some aspects of the interaction of parasitoidism associated to N. perezi larvae ; in addition to characterize the vital development of the insect under laboratory controlled conditions and finally describe the stages of egg, larva and adult on the insect. Analyses were carried out fortnightly in each area of study from March 2008 to February 2009 in order to obtain the levels of parasitism by larvae of N. perezi in cassava shoots and parasitoidism levels by Braconidae parasitoids of the fly larvae. In analyzing the genotypes in relation to the infestation by N. perezi, these were planted in the experimental area of Plant Biology Department at the State University of Campinas and so the level of infestation was calculated for each genotype, from June 2008 to January 2009. Finally the life cycle study of the fly was carried out by collecting eggs in the field, which have been kept on a diet drawn up in this research in which made it possible for the total development, from the egg to the adult one of N. perezi. The results indicate that the fly population dynamics in the buds in the studied region is correlated, separately, with temperature, rainfall and the age of plants, so that temperature above 23ºC, or elatively high quantity of rains or even late plant ages seem negatively affect the population of this insect. Furthermore, the infestation by the fly behaved differently in the face of the different genotypes in a way that the genotype IAC Caapora 105-66 and genotype IAC Cascuda are less susceptible to infestation by this insect while the genotype IAC 15 presented the highest percentages of infestation. Regarding to parasitoidism by braconideous in N. perezi larvae was found that parasitoidism percentage was fairly high suggesting that this interaction can be an important factor in N. perezi populational dynamics. Thus, we have established a short description of biological and ecological aspects of N. perezi, which will make subsequent studies easier related to this family, as well as elucidate certain parasitism aspects of these larvae in cassava shoots which may be used in possible risks explanation to the crop of this plant / Mestrado / Mestre em Parasitologia

Fitoplasmas são agentes causais de diversas doenças em numerosas espécies botânicas cultivadas, daninhas e silvestres. São procariotos que não apresentam parede celular, parasitas intracelulares obrigatórios, habitantes do floema e da hemolinfa, sendo transmitidos naturalmente por insetos vetores do tipo cigarrinhas. Plantas de oliveira apresentando sintomas tipicamente induzidos por fitoplasmas, caracterizados por desenvolvimento lento e superbrotamento de ramos com folhas de tamanho reduzido, foram observadas na cidade de Extrema (MG). A anomalia provoca danos significativos, pois retarda o início de produção e reduz o rendimento da cultura. Sintomas semelhantes foram relatados em olivais implantados em outros países, onde a doença foi associada aos fitoplasmas. O objetivo deste trabalho foi demonstrar a associação de fitoplasma com as plantas afetadas e identificar o fitoplasma presente nas árvores doentes. Para isto foram utilizadas as técnicas moleculares de PCR e RFLP, além de análise filogenética. Os resultados revelaram a presença de fitoplasmas em 73% das árvores sintomáticas analisadas, evidenciando que os sintomas observados no campo eram induzidos por fitoplasma. A doença foi denominada de vassoura-de-bruxa da oliveira. A identificação molecular permitiu classificar o fitoplasma como um representante do grupo 16SrVII-B. Este é o primeiro relato da ocorrência de fitoplasma em plantas de oliveira no Brasil. Em termos mais amplos, é o primeiro relato da associação de um fitoplasma do grupo 16SrVII com a doença vassoura-de-bruxa da oliveira, a qual, em outros países, está associada a fitoplasmas distintos do fitoplasma identificado no presente trabalho. / Phytoplasmas are causal agents of diverse diseases occurring in numerous botanical species, among them cultivated, weeds and wild plants. They are wall-less prokaryotes, obligate intracellular parasites, inhabitants of phoem vessels and hemolymph, and naturally transmitted by insect vectors belonging to the group of the leafhoppers. Olive trees exhibiting symptoms typically induced by phytoplasmas, characterized by slow growth and shoot proliferation with small leaves, were observed in the municipality of Extrema (MG). The anomaly provokes significant damage due to the delay in the beginning of the production and yield reduction of the crop. Similar symptoms have been reported in olive orchards cultivated in other countries, where the disease was associated with phytoplasmas. The objective of the present investigation was to demonstrate the association of phytoplasma with affected plants and identify the phytoplasma present in diseased trees. PCR assays, RFLP analysis and phylogenetic analysis were used to molecular characterization of the phytoplasma. The results revealed the presence of phytoplasma in 73% of the symptomatic trees, evidencing that the symptoms observed in field were induced by phytoplasma. The disease was designated by olive witches\" broom. The molecular identification allowed classify the phytoplasma as a representative of the 16SrVII-B group. This is the first report of the occurrence of phytoplasma in olive plants in Brazil. Moreover, this is also the first report of the association of a group 16SrVII phytoplasma with olive whitches\" broom disease, which has been described in other countries in association with phytoplasmas different from the phytoplasma identified in the present study.