Orientador: João Domingos Rodrigues / Banca: Elizabeth Orika Ono / Banca: Fernando Broetto / Banca: Teresinha Costa S.de Albuquerque / Banca: Barbara Franca Dantas / Resumo: A videira por ser originária de regiões de inverno rigoroso, apresenta mecanismo de dormência que conferem condições de sobrevivência durante o período frio. Contudo, esta mesma espécie também é cultivada em condições tropicais, cuja ausência de estação com baixas temperaturas favorece seu contínuo desenvolvimento vegetativo, fazendo-se necessário estabelecer um repouso, que normalmente é promovido com a redução do fornecimento de água, através do controle da irrigação. No entanto, este processo, apesar de ter o mesmo objetivo da dormência estabelecida pelo frio, apresenta mecanismos fisiológicos e bioquímicos diferentes. Este trabalho teve o objetivo de avaliar características fisiológicas e bioquímicas de plantas de Vitis vinifera L. cv. Thompson Seedless submetidas às condições de frio e deficiência hídrica, assim como sua influência na brotação de gemas. As plantas foram conduzidas em casa-de-vegetação e submetidas aos seguintes tratamentos: 1. Controle (25-30oC / 60-70% U.R. em capacidade de campo - cc); 2. Deficiência Hídrica (25-30oC / 60-70% U.R. a uma tensão de água no solo entre -80 a -100 kPa); 3. Frio (5-13oC / 60-70% U.R. em câmara climatizada e em cc), por um período de até 90 dias, sendo cada parcela de plantas avaliada e amostrada a cada 15 dias, para em seguida ser reconduzida às condições de Controle (25-30oC/60-70%U.R em cc), onde permaneceram até a brotação. O delineamento foi inteiramente casualizado, em esquema de parcela subdividida (3 x 6); sendo a parcela representada pelos três tratamentos; enquanto a subparcela representada pelos seis tempos de permanência que as plantas foram submetidas aos tratamentos (15, 30, 45, 60, 75 e 90 dias após o tratamento - DAT). O número de repetição variou de acordo com o tipo de característica avaliada (destrutiva e não destrutiva) e cada unidade experimental foi constituída... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The vine is from cold winter regions and because this has dormancy mechanism conferring survival conditions during the cold period. However, these species are also cultivated in tropical conditions and absence of season with low temperatures increase vegetative growth, and because this is necessary to establish a dormant which usually is promoted with reducing water supply through irrigation control. But while used in place of cold dormancy, irrigation control has different biochemical and physiological mechanisms, this way, the aim were to evaluate physiological and biochemical characteristics of Vitis vinifera L. cv. Thompson Seedless plants submitted to cold and drought conditions, as well as its influence on bud break. Plants were growing in a green house and treated as follows: 1. Control (25-30oC / 60-70% RH at field capacity - cc), 2. Water deficiency (25-30oC/60-70% RH at a soil water tension between -80 to -100 kPa) 3. Cold (5-13oC/60-70% RH in an growth chamber acclimatized at cc), for a period up to 90 days, and plants portion were sampled and evaluated each 15 days, to then be brought back to Control conditions (25-30oC/60-70% RH in cc), where they remained until budding. The design was completely randomized in a split plot design (3 x 6) being three main treatments and sub plots constituted by six permanence time which plants were treated (15, 30, 45, 60, 75 and 90 days after treatment - DAT). The repetition number varied according characteristic evaluated (destructive and non destructive) and each plant represented one experimental unit. The following physiological characteristics were evaluated: rate of net CO2 assimilation... (Complete abstract click electronic access below) / Doutor

O cancro cítrico é uma das doenças mais temidas da citricultura devido ao seu poder de proli-feração nas fazendas, aos danos causados às plantas e aos frutos e à forma de combate adota-da pelos órgãos responsáveis através da erradicação das plantas contaminadas e de outras em sua vizinhança. No Brasil, um dos principais motivos que minimiza a eficiência da erradicação do cancro cítrico é a confirmação do diagnóstico, que necessita ser realizada em alguns laboratórios credenciados. A análise de muitas amostras em conjunto com o tempo gasto com o transporte aumenta a chance de proliferação da doença no campo. Neste trabalho aplicamos técnicas de espectroscopia da fluorescência em folhas de culturas cítricas na intenção de pro-por um método de diagnóstico do cancro cítrico a ser realizado na fazenda e com resposta em tempo real. As amostras experimentais são folhas de variedades cítricas sadias e contaminadas com cancro ou outras doenças. Iniciamos o trabalho aplicando espectroscopia da fluorescência no laboratório. Os resultados provaram a viabilidade do método, mas revelou uma enorme sobreposição de dados ao tentar discriminar o cancro de outra doença. Análises com-plementares nos revelaram que os experimentos deveriam ser feitos no campo, identificando plantas contaminadas e tomando a fluorescência de folhas sadias como referência. A espec-troscopia da fluorescência no campo foi feita com um espectrômetro portátil. O resultado nos possibilitou propor critérios de discriminação do cancro baseado em figuras de mérito. O melhor critério apresentou 79% de acertos, com 88% de sensibilidade e 68% de especificidade. Concluímos que os valores poderiam ser melhores se a espectroscopia fosse realizada com imagens, pois as variações do espectro ocorrem devido ao posicionamento da fibra na lesão do cancro. Passamos a estudar a espectroscopia das imagens da fluorescência com um sistema baseado em um espectrógrafo. Os resultados provaram a viabilidade do estudo e revelaram particularidades espaciais e espectrais das doenças. Infelizmente essa instrumentação só pode ser usada no laboratório, por isso optamos por desenvolver outro sistema mais simples e robusto, a base de uma roda de filtros com filtros passa-banda. Os re-sultados revelaram novas particularidades espaciais e espectrais das amostras, porém nos revelou a necessidade de um processamento de imagem para obter análises quantitativas. O sistema de imagens com filtro ainda foi usado em outro experimento complementar onde as imagens forneceram resultados quantitativos, provando a funcionalidade da técnica. / Citrus canker is one of the most feared diseases of citrus due to its dissemination in the farms, the damage caused to plants and fruits and how to combat adopted by national government through the eradication of infected plants and others in your neighborhood. In Brazil, one of the main reasons that minimizes the effectiveness of citrus canker`s eradication is the confir-mation of the diagnosis by specialized laboratories. The time spent to transport and to analyses many samples increases the chance of canker spreading in the field. In our work we apply spectroscopic techniques of fluorescence in leaves of citrus crops with the aim to propose a method for diagnosis of citrus canker to be held on the farm and real-time response. The expe-rimental samples are leaves of healthy citrus varieties and contaminated with canker or other diseases. We began the work by applying fluorescence spectroscopy in the laboratory. The results proved the feasibility of the method, but showed a huge overlap of data to try to dis-criminate cancer from other diseases. Further analysis revealed that those experiments should be done in the field, focusing to identify infected plants and taking the fluorescence of healthy leaves as a reference. Fluorescence spectroscopy in the field was made with a portable spectrometer. The result allowed us to propose some criteria for canker discrimination based on figures of merit. The best criteria presents 79% correct tests, with 88% sensitivity and 68% specificity. We conclude that these values could be better if the spectroscopy was performed with images, because the variations of the spectrum are due to the positioning of the fiber over the canker lesion. We study the spectroscopy of fluorescence images with a system based on a spectrograph. The results proved its feasibility and revealed spatial and spectral particular features of the diseases. Unfortunately, this instrumentation can only be used in the laborato-ry, so we decided to develop another system more simple and robust. The new system is based on a filter wheel with band-pass filters. The results revealed new spatial and spectral characteristics of the samples, but revealed the need for an image processing for quantitative analysis. This imaging system was still used in another supplementary experiment where the images have provided quantitative results, proving the functionality of the technique.

Plantas medicinais (fitoterápicos) têm uma longa história nos tratamentos de várias desordens de saúde. Nos últimos anos, por suas propriedades medicinais, o interesse no uso de Mikania, um gênero da família Asteraceae, como alternativa ou terapia complementar tem crescido notavelmente. Especificamente, duas espécies de Mikania, M. glomerata e M. laevigata, amplamente conhecidas como \"guaco\" são utilizados para tratar febre, asma, bronquite e outras doenças respiratórias, devido ao seu teor de cumarina, o principal componente desta planta. No entanto, devido à excessiva exploração humana, estas espécies de Mikania se tornaram espécies ameaçadas. O objetivo do presente estudo foi determinar o melhor ambiente para o crescimento de M. glomerata e M. laevigata, quantificando os efeitos de quatro tratamentos de radiação, pleno sol e 25, 50 e 75% de interferência da radiação e de duas condições nutricionais do solo, fertilizado e não fertilizado, sobre o teor de clorofila, fluorescência da clorofila, trocas gasosas, anatomia foliar e produção de biomassa vegetal. Os níveis de irradiância e as condições nutricionais do solo afetaram significativamente o crescimento e as respostas fisiológicas das plantas de ambas as espécies Mikania. As plantas que cresceram à sombra apresentaram menores taxas fotossintéticas, enquanto as plantas sob maior radiação apresentaram maiores taxas fotossintéticas e condutância estomática. A redução da intensidade luminosa em 75% resultou em irradiação insuficiente para manter a fotossíntese, influenciando o balanço de carbono e, conseqüentemente, causando um declínio no crescimento e produtividade das plantas. A fotoinibição, avaliada como a razão Fv/Fm, ocorreu somente em plantas crescidas sob pleno sol e 25% da radiação interferência durante o pico mais alto de radiação e temperatura. As maiores concentrações de clorofila, independentemente da adubação, ocorreram em plantas sob 75% da radiação interferência. A espessura da lâmina foliar diminuiu com o aumento da interferência da radiação. As folhas de M. glomerata que não receberam adubação apresentaram, no final do experimento, maior espessura do limbo do que as plantas adubadas nas condições 0 e 25% de interferência da radiação, enquanto que M. laevigata não adubadas apresentaram maior espessura do limbo sob 25 e 50% de interferência da radiação. A densidade estomática aumentou com baixa radiação interferências, e em M. glomerata foi maior em plantas sem adubação. A massa seca total foi maior em plantas sob maior intensidade luminosa, e em plantas adubadas. O uso de fertilizantes e pouco sombreamento é a melhor recomendação para uma maior produção de massa seca, especialmente de folhas, que é o material utilizado na fitoterapia. Em virtude da baixa capacidade de aclimatação a elevado sombreamento destas espécies de Mikania, áreas cultivadas com intensidade luminosa menor do que 50% de luz ambiente irão diminuir a produtividade. Assim, para fins agrícolas, a fim de obter rendimentos elevados, a partir dos resultados desta pesquisa se recomenda o uso de aproximadamente 25% da interferência da radiação para M. laevigata e indistintamente, o cultivo em pleno sol ou interferência da radiação de 25% para M. glomerata. / Medicinal plants (phytotherapics) have a long history as treatments for several health disorders. In recent years, interest in the use of Mikania, a genus of the Asteraceae family, as alternative or complementary therapies for its medicinal properties has grown notably. Specifically, two Mikania species, M. glomerata e M. laevigata, widely know as guaco are used to treat fever, asthma, bronchitis and other respiratory diseases due to its content in coumarin, the main constituent of this plant. However, due to human overexploitation these Mikania species have become endangered species. The objective of the present study was to determine the optimum environment for the growth of M, glomerata and M, laevigata, by quantifying the effects of four light treatments, full sun and 25, 50 and 75% light interference and two soil nutrient conditions, fertilized and unfertilized, on the chlorophyll content, chlorophyll fluorescence, gas exchange, leaf anatomy and plant biomass production. Light irradiance levels and soil nutrient conditions significantly affected the growth and physiological responses of both Mikania species. The plants that grew in the shade presented lower photosynthetic levels, while the plants under higher radiation had larger photosynthetic rates and stomatal conductance. Light intensity reductions greater than that of 75% shade resulted in insufficient irradiation to maintain photosynthesis, influencing carbon balance and consequently leading to a decline in plant growth and productivity. The photoinhibition, evaluated at the rate Fv/Fm, occurred only in plants grown under full sun and 25% of radiation interference during the highest peak of radiation and temperature. The larger concentrations of chlorophyll, regardless fertilizing, occurred in plants under 75% of radiation interference. The thickness of the leaf blade decreased significantly with the increase of radiation interference. However, the M. glomerata leaves that were no fertilized presented, at the end of the experiment, bigger leaf blade thickness than the fertilized plants under 0 and 25% interference radiation conditions, while unfertilized M. laevigata had bigger leaf blade thickness under 25 and 50% interference radiation. The stomatal density enlarged under lower radiation interference, and in M. glomerata it was bigger in unfertilized plants. The total dry mass was bigger in plants under higher light intensity and in fertilized plants. The use of fertilizing and little protection to radiation is the best recommendation to a bigger production of dry mass, especially of leaves, that is the material used in phytotherapie. In view of the low shade acclimation capacity of these Mikania species, light intensity of cultivated areas with less than that of 50% ambient light will decrease the productivity. Thus, for agricultural purposes, in order to obtain high yields, the results of this study suggest trying to achieve approximately 25% ambient light interference with a shade net for M laevigata and indistinctively, the cultivation under full sun or 25% ambient light interference for M. glomerata.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-05-19T13:27:03Z No. of bitstreams: 2 Dissertação - Frederico Rocha Rodrigues Alves - 2015.pdf: 1259863 bytes, checksum: 11ef140f010d95a139261c29d420502b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-05-19T13:30:17Z (GMT) No. of bitstreams: 2 Dissertação - Frederico Rocha Rodrigues Alves - 2015.pdf: 1259863 bytes, checksum: 11ef140f010d95a139261c29d420502b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-05-19T13:30:17Z (GMT). No. of bitstreams: 2 Dissertação - Frederico Rocha Rodrigues Alves - 2015.pdf: 1259863 bytes, checksum: 11ef140f010d95a139261c29d420502b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-02-26 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Phytochrome-dependent physiological processes are being unveiled by photomorphogenic mutant plants. In tomato (Solanum lycopersicum L.), the aurea mutant is phytochrome-deficient and the high-pigment 1 mutant (hp1) has exaggerated light responses. Phytochromes are related to many abiotic and biotic stress responses due to its role in the regulation of specific genes transcription, acting upon biochemical and molecular mechanisms of cell signaling. Here, we examined the effects of water-withholding over water potential, leaf gas exchanges, chlorophyll fluorescence parameters and chloroplast pigments content in photomorphogenic tomato mutants aurea and hp1, as well its wild-type cultivar Micro-Tom (MT). The plants were grown in a greenhouse under controlled conditions of temperature (24-27ºC) and humidity (60-70%). Analysis were made in 35-days-old plants (n=5) which irrigation was suspended for 5 days and then rehydrated in the sixth day. As control, five plants of each genotype remained well-watered. Water-withholding decreased the water potential and affected leaf gas exchange rates in all studied genotypes, decreasing rates of photosynthesis and stomatal conductance from the fourth treatment day on. Initial fluorescence and PSII potential quantum efficiency were not affected by the water-withholding treatment in general, but MT showed significant decrease in PSII operating efficiency and electron transporte rate as well as an increase in non-photochemical quenching parameters, facts not registered for the mutants during the treatment period. hp1 mutant has the highest content of chlorophyll a, chlorophyll b and carotenoids, this last playing a central role in the oxidative stress defense. Under water-withholding conditions, MT presented the highest MDA concentration and aurea displayed high activities of catalase, peroxidase and ascorbate peroxidase when compared to the other genotypes. The present data allows the conclusion that the mutants have higher tolerance to drought stress than the wild Micro-Tom genotype. / Processos fisiológicos dependentes de fitocromos estão sendo elucidados por meio de plantas mutantes fotomorfogenéticos. Em tomate (Solanum lycopersicum L.), o mutante aurea é deficiente em fitocromo e o mutante high-pigment 1 (hp1) possui respostas exageradas à luz. Fitocromos estão relacionados a várias respostas de estresse abiótico e biótico devido ao seu papel na regulação da transcrição de genes específicos, agindo sobre mecanismos bioquímicos e moleculares de sinalização celular. Neste trabalho, foram analisados os efeitos da deficiência hídrica sobre o potencial hídrico, as taxas de trocas gasosas, parâmetros de fluorescência da clorofila, conteúdo de pigmentos cloroplastídicos e malondialdeído (MDA) e atividade de enzimas do metabolismo antioxidativo de tomateiros mutantes fotomorfogenéticos aurea e hp1, bem como a cultivar selvagem Micro-Tom (MT). As plantas foram cultivadas em casa de vegetação sob condições controladas de temperatura (24-27ºC) e umidade (60-70%). As análises foram realizadas em plantas de 35 dias de idade (n=5) cuja irrigação foi suspensa por 5 dias e reidratadas no sexto dia. Como grupo controle, cinco plantas de cada genótipo permaneceram sob disponibilidade hídrica normal. A deficiência hídrica diminuiu o potencial hídrico e afetou as taxas de trocas gasosas de todos os genótipos analisados, com quedas nas taxas de fotossíntese e condutância estomática a partir do quarto dia de tratamento. Em geral, os parâmetros de fluorescência inicial e rendimento quântico potencial não foram afetados pela deficiência hídrica, enquanto MT apresentou queda significativa para o rendimento quântico efetivo, taxa de transporte de elétrons e aumento do quenching não-fotoquímico, fatos não registrados para os mutantes durante o período de tratamento. O mutante hp1 possui maior concentração de clorofila a, clorofila b e carotenoides, este último com papel crucial na defesa contra o estresse oxidativo. Em condições de déficit hídrico, MT deteve maior conteúdo de MDA em relação aos mutantes e aurea possui maior atividade de catalase, peroxidase e ascorbato peroxidase. Os dados permitem concluir que os mutantes apresentam maior tolerância à deficiência hídrica em relação a cultivar selvagem.

Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2016-10-10T12:27:32Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tese_cristiane_velleda_brisolara.pdf: 2089342 bytes, checksum: f1939984be81e24a95f3d1afdd2f4eb0 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-10-11T20:59:58Z (GMT) No. of bitstreams: 2 tese_cristiane_velleda_brisolara.pdf: 2089342 bytes, checksum: f1939984be81e24a95f3d1afdd2f4eb0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-10-11T21:01:13Z (GMT) No. of bitstreams: 2 tese_cristiane_velleda_brisolara.pdf: 2089342 bytes, checksum: f1939984be81e24a95f3d1afdd2f4eb0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-10-11T21:01:24Z (GMT). No. of bitstreams: 2 tese_cristiane_velleda_brisolara.pdf: 2089342 bytes, checksum: f1939984be81e24a95f3d1afdd2f4eb0 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2013-09-02 / Sem bolsa / A presença de sementes esverdeadas em lotes de sementes de soja representa um alerta da ocorrência de condições adversas durante o processo de maturação. A variação na intensidade luminosa é um fator abiótico que pode provocar a formação de sementes esverdeadas em vista que as respostas fisiológicas das plantas à essas variações passa pela adaptação e otimização na coleta da luz, melhorando a capacidade do aparelho fotossintético em converter a energia luminosa em uma forma utilizável. O objetivo deste trabalho foi avaliar a produção de sementes esverdeadas sob níveis de sombreamento e seus e seus efeitos na qualidade fisiológica do lote, relacionando a mensuração da fluorescência da clorofila na semente. Primeiramente (fase I), a soja, cv. IGRA 518 RR, foi semeada sob o regime de três níveis de sombreamento (0%, 30% e 50%) com aplicação de inseticida e fungicida. Foi avaliada a interação entre sombreamento e aplicação de químicos e seus efeitos na produção de sementes esverdeadas. Posteriormente (fase II), três cultivares de soja foram submetidas a quatro níveis de sombreamento, 0%, 35%, 50% e 65%. Foram realizados testes de qualidade no Laboratório de Análise de Sementes da Universidade Federal de Pelotas e também nas instituições holandesas Plant Research International e Wageningen University. Os equipamentos CF Seed Sorter and Analyser - Model JS 2001 e CropReport, sensíveis aos compostos incolores e fluorescentes, foram utilizados para mensurar a clorofila em sementes e durante o processo de absorção de água, respectivamente. O sombreamento em plantas de soja age no mecanismo fotossintético, fazendo com que a degradação da clorofila não ocorra normalmente, acarretando aumento da presença de moléculas fluorescentes independentemente do nível de sombreamento aos quais as plantas foram submetidas. Plantas de soja sombreadas durante a fase de enchimento de grão produzem sementes com teor de clorofila aumentado, predispondo a produção de sementes com maior emissão de fluorescência da clorofila, mesmo sem apresentar coloração verde em seu tegumento. / The presence of green seeds in seed lots of soybean as a warning of the occurrence of adverse conditions during the maturation process. The physiological response of plants to variation in light intensity passing through the adaptation and optimization of light collection in improving the capacity of the photosynthetic apparatus to convert light energy into a usable form. The purpose of this study was to evaluate levels of shading in the production of green seeds and their physiological effects on the quality of the lot, using the measurement of chlorophyll fluorescence. Firstly (step I), soybean cv. IGRA 518 RR was seeded under the scheme three shading levels (0%, 30% and 50%) with application of insecticide and fungicide. It was evaluated interaction between shading and application of chemicals and their effects on the production of green seed. Subsequently (phase II) three soybean cultivars were subjected to four levels of shading, 0%, 35%, 50% and 65%. Quality tests were performed at the Laboratory of Seed Analysis, Federal University of Pelotas and also in Dutch institutions Plant Research International and Wageningen University. Equipment sensitive fluorescent and colorless compounds were used to measure chlorophyll in seeds and during the process of water absorption. The shading in soybean acts on the photosynthetic mechanism, causing degradation of chlorophyll does not usually occur, leading to the increased presence of fluorescent molecules irrespective of the level of shading which the plants were submitted. Seeds of soybean shaded during the grain filling phase producing seeds with increased chlorophyll content, predisposing the production of seeds with higher chlorophyll fluorescence emission, green coloration without providing in its tegument.

Made available in DSpace on 2014-08-20T13:59:08Z (GMT). No. of bitstreams: 1 dissertacao_marcio_espinosa_de_farias.pdf: 3645960 bytes, checksum: 2a09be33a4c426dea1aef53c4073f253 (MD5) Previous issue date: 2014-02-17 / Photosynthesis plays a fundamental role in the processes of growth and development of plants. It occurs in the chloroplasts of leaf mesophyll cells and consists of two steps, a photochemical phase that converts light energy into chemical energy, and other biochemical phase, which uses the energy of the first step for fixing CO2. The study aimed to evaluate, in detached leaves of pea (Pisum sativum L.), the behavior of the electron transport chain in the presence of inhibitors of specific points. The plants were grown in a greenhouse. Two to four weeks after sowing, when the leaves had become fully expanded, they were detached and the petioles were immersed in solutions containing 0, 25, 50, 100, 250, and 500 μM of DCMU, atrazine, DBMIB and methyl viologen. To DCMU, atrazine and methyl viologen the leaves remained for 2 h in contact with the solutions, to DBMIB was 5h. Measurements of transient fluorescence of chlorophyll, delayed fluorescence and modulated reflection at 820nm were made using M-PEA fluorometer. The leaves were dark adapted for 30 minutes, before a saturating pulse emission, and the fluorescence intensities were measured for 60 seconds. Pea leaves treated with 500 μM concentration of DCMU and atrazine showed to be sensitive to this dose of inhibitors, in analyzing the results of transient fluorescence, delayed fluorescence and modulated reflection at 820 nm. The leaves treated with 500 μM of methyl viologen showed differences in parameters related to the mechanism of action of the inhibitor.The same concentration used to DBMIB, had no significant difference in many results compared to the control, only in those involved in the reduction of end acceptors of photosystem I. Therefore, a detailed analysis of the transient fluorescence, delayed fluorescence and modulated reflection at 820nm, allows us to collect and correlate a series of information about the whole electron transport chain. / A fotossíntese exerce um papel fundamental para os processos de crescimento e desenvolvimento das plantas. Ela ocorre nos cloroplastos das células do mesofilo foliar e consiste de duas etapas, uma fase fotoquímica, que converte energia luminosa em energia química e outra fase bioquímica, que utiliza a energia da primeira etapa pra a fixação do CO2. O trabalho teve como objetivo avaliar, em folhas destacadas de ervilha (Pisum sativum L.), o comportamento da cadeia de transporte de elétrons na presença de inibidores de pontos específicos. As plantas foram cultivadas em casa de vegetação. Duas a quatro semanas após semeadura, quando as folhas apresentavam-se completamente expandidas, elas foram destacadas e os pecíolos foram imersos em soluções contendo 0, 25, 50, 100, 250 e 500 μM de DCMU, atrazina, DBMIB e metil viologênio. Para DCMU, atrazina e metil viologênio as folhas permaneceram por 2h em contato com as soluções, para o DBMIB foi de 5h. As medidas da fluorescência transiente da clorofila, da decaída de fluorescência e da reflexão modulada à 820nm, foram feitas utilizando fluorômetro M-PEA. As folhas foram adaptadas ao escuro por 30 minutos, antes da emissão de um pulso saturante, e as intensidades de fluorescência foram medidas por 60 segundos. As folhas de ervilha tratadas com a concentração de 500 μM de DCMU e atrazina demonstraram ser sensíveis a essa dose dos inibidores, ao analisar os resultados da fluorescência transiente, decaída de fluorescência e da reflexão modulada a 820 nm. As folhas tratadas com 500 μM de metil viologênio apresentaram diferenças nos parâmetros relacionados com o mecanismo de ação do inibidor. A mesma concentração utilizada para DBMIB, não teve diferença em muitos resultados em relação ao controle, apenas naqueles envolvidos com a redução dos aceptores finais do fotossistema I. Dessa maneira, uma análise detalhada da fluorescência transiente, da decaída da fluorescência e da reflexão modulada a 820 nm, permite coletar e correlacionar uma série de informações sobre toda a cadeia de transporte de elétrons.

Chickpea (Cicer arietinum) is an important legume crop globally ranked third after dry bean (Phaseolus vulgaris) and field pea (Pisum sativum). It constitutes 20% of the total global pulse production and around 95% of its production and consumption takes place in developing countries. Major constraints to chickpea production in sub Saharan Africa (SSA) have broadly been related to abiotic stresses, particularly drought and heat stresses, predicted to increase due to the global climatic changes.Dueto the imperativeness of research for identifying heat tolerance markers for potential chickpea genotype selection, in chapter two of the thesis, the response of four chickpea genotypes to a natural temperature gradient in the field was assessed using chlorophyll fluorescence, non-structural carbohydrate, gas exchange and grain yield. Field experiments were carried out in two winter seasons at three locations with known differences in temperature in NE South Africa. Results showed two genotypes (Acc#3 and Acc#7) were tolerant to heat stress with an Fᵥ/Fₘ of 0.83-0.85 at the warmer site, while the two sensitive genotypes (Acc#RR-2 and Acc#8) showed lower Fᵥ/Fₘ of 0.78-0.80. Both chlorophyll fluorescence measurements: dark-adapted Fᵥ/Fₘ and Fq'/Fₘ' (where Fq' =Fₘ'–F) measured at comparable high light levels correlated positively with grain yield. The two tolerant genotypes also showed higher photosynthetic rates,starch, sucrose and grain yield than the sensitive genotypes at the warmer site. However, these parameters were consistently higher at the cooler than at the warmer sites. It was concluded that genotypes Acc#RR-3 and Acc#7 are heat tolerant and chlorophyll fluorescence and leaf carbohydrates are suitable tools for selection of heat tolerant chickpea genotypes under field conditions. The coolest site of Polokwane showed favourable conditions for chickpea production.Heat and drought stresses are two abioticfactors that often occur simultaneously and are predicted to increase, consequently hampering plant growth. Response of different species to either stresses is well documented but information on the response of the same genotypes to both stresses in chickpea is limited. We aimed to determine whether previously noted heat stress tolerant genotype (Acc#7) is drought tolerant and the heat sensitive (Acc#8) is drought sensitive, and whether intermittent moisture supply at vegetative stage would induce priming effect to later drought at flowering. At vegetative stage, plants were divided into three groups, non-stressed (watered to 75% field capacity (FC), severe water stress (moisture-withholding for 14 days) and treated to 40% FC throughout the experiment (mild-stress), with recovery for the severely stressed plants after which they were stressed (double-stress) at flowering. Drought treatments at vegetative and flowering growth stages decreased physiological parameters and biomass accumulation in both genotypesexcept low water supply at 40% FC that decreased biomass in Acc#7 but not Acc#8. Double drought stress resulted in priming effect in Acc#7, having higher biomass, chlorophyll fluorescence, stomatal conductance, net photosynthesis, and relative water content in comparison to the introduction of stress only at flowering growth stage, as well as in comparison to Acc#8. These results showed that both Acc#7 and Acc#8 are sensitive to drought whereas after priming Acc#7 is better acclimated to drought than Acc#8 associated with osmotic adjustment on leaf relative water content (RWC) and higher capacity to protect photosynthetic activity, making Acc#7 potentially ideal for areas associated with intermittent drought spells. This observation, however, disapproved the hypothesis that Acc#7 is more drought tolerant than Acc#8 but is rather better acclimated than Acc#8, because of its superiority only in primed plants and not those stressed only at either vegetative or flowering stages. The findings emphasise the importance of matching chickpea physiological performance to expected rainfall amounts and distribution in drought prone areas during genotype selection. Chapter four of the thesis was an interrogative proteome analysis of the differences in the heat tolerant and sensitive chickpea (Cicer arietinumL.; Fabaceae) genotypes along a temperature gradient under field conditions which will help in identifying the molecular mechanisms involved in the crop's tolerance. Few studies have thus far combined chickpea physiological and proteome analysis to elucidate the changes in abundance and/or activity of relevant enzymes and expression of heat responsive proteins. In this study, analyses of chlorophyll concentrations, gas exchange, flavonoids and anthocyanin concentrations from a chamber experiment, as well as proteomic parameters from field studies in both the heat tolerant and sensitive genotypes are presented. The heat tolerant genotype Acc#7 maintained unaltered physiological performance at flowering growth stage when exposed to high (35/30°C) and moderate (30/25°C) heat stress, under climate chamber conditions compared to the two heat susceptible genotypes (Acc#RR-2 and Acc#8). Results from the proteomic studies showed an up-regulation in proteins related to protein synthesis (e.g. ribulose bisphosphate carboxylase/oxygenase activase), intracellular traffic (e.g. mitochondrial dicarboxylate/tricarboxylate transporter DTC), defence (e.g. HSP70) and transport (e.g. GTP-binding protein SAR1A-like) in heat tolerant Acc#7 compared to the susceptible Acc#8. Results from KEGG analyses support the involvement of probable sucrose-phosphate synthase and sucrose-phosphate phosphatase proteins in the starch and sucrose pathway,that were up-regulated in the heat tolerant genotype Acc#7. This result was in support of our earlier report where tolerant genotype Acc#7 had higher leaf starch and sucrose concentrations in comparison to the susceptible genotype Acc#8. The presence of these differentially regulated proteins including HSP70, ribulose bisphosphate carboxylase/oxygenase activase, plastocyanin and protoporphyrinogen oxidase shows their potential role in field grown chickpea tolerance to heat stress at flowering growth stage. In conclusion, chlorophyll fluorescence (both Fᵥ/Fₘ and Fq'/Fₘ') and leaf carbohydrates were identified as selection markers that can potentially be used for chickpea phenotyping for heat stress under field conditions with the chlorophyll fluorescence parameters correlating positively with seed yield. Due to its higher biomass, chlorophyll fluorescence (Fᵥ/Fₘ), stomatal conductance, net photosynthesis and RWC, heat tolerant genotype Acc#7 was identified to have better adaptive tolerance to drought stress after priming through exposure to intermittent dry spells than Acc#8. Furthermore, under controlled climate chamber conditions, Acc#7 consistently showed characteristics of tolerance to heat stress while Acc#RR-2 and Acc#8 were heat susceptible. Higher chlorophyll fluorescence, grain yield, chlorophyll concentrations, gas exchange, flavonoids and anthocyanin concentrations for Acc#7 compared to Acc#8 in the climate chamber was further validated by the higher up-regulation of proteins involved in protein synthesis, intracellular traffic, defence and transport in Acc#7 compared to Acc#8. The incorporation of proteomics in heat and drought stress studies will potentially help further the understanding of mechanisms by which the crop responds to these stresses.

Damage to primary photosynthetic reactions caused by environmental stress can be assessed by measurement of chlorophyll fluorescence induction in intact leaves. This approach was applied in studies of ultraviolet-B photoinhibition of photosynthesis in Pisum sativum L. and Rumex patientia L. leaves. At ultraviolet-B dose rates insufficient to cause inhibition of net photosynthesis, changes in the magnitude of fluorescence transients did occur, which suggested direct effects on chloroplast pigments in Pisum and inhibition of photosynthetic electron transport between the photosystems in both species. Leaves of these two species subjected to a much higher dose rate had a significant reduction of net photosynthesis and changes in the magnitude of fluorescence transients that indicated partial loss of water-splitting capability and direct effects on chloroplast pigments. Ultraviolet radiation-induced changes of photosynthetic thylakoid membranes may be ultimately responsible for these disruptions of the primary photosynthetic reactions.

Climate change models predict an increase in frequency and amplitude of extreme weather events, including heat waves. To better predict how the composition and distribution of plant assemblages might respond to these changes in temperature, it is important to understand how species currently respond to these extremes. Photosynthetic thermal tolerance (T25)and photosynthetic recovery (RT25) were quantified in 27 species. We also studied the relationships between T25, RT25 and leaf mass per area (LMA). Leaf temperature was also monitored in the field. Leaves used in this study were collected from two distinct environments representing desert and montane plant assemblages. T25 and RT25 were measured using a chlorophyll fluorescence protocol incorporating sub-saturating light and short duration heat stress. Mean T25and LMA were significantly different between environments. Mean RT25 was not significantly different between environments. There was a positive relationship between T25 and LMA in both environments. The ability to recover from heat stress does not differ between two biomes that experience vastly different mean maximum temperatures during the summer months. LMA is a predictive leaf trait for thermal tolerance.

Methods for rapid, safe and effective detection of unmapped buried ordnance are vital to the protection of humans and environmental quality throughout the world. This study aimed to investigate the use of phytosensing and to understand the physiological response of woody plants to 2,4,6-trinitrotoluene (TNT) contamination. Baccharis halimifolia were potted in soils containing various concentrations of TNT and physiological responses were observed over a 9-week experimental period. Measurements included the collection of remotely sensed data, such as hyperspectral reflectance and chlorophyll fluorescence, and traditional plant-level physiological data. In accordance with the hypothesis, low levels of TNT improved physiological response in plants due to the slight increase in nitrogen, while high levels of TNT induced stress. Key markers in stress responses were identified, specifically with reflectance indices and derivatives, which may separate TNT-contaminated plants from naturally stressed plants and would allow for accurate detection of buried ordnance at the landscape level.