Made available in DSpace on 2014-08-20T13:59:11Z (GMT). No. of bitstreams: 1 dissertacao_anelise_tessari_perboni.pdf: 3085637 bytes, checksum: c55ca1817bac9993117c80d2a3e5179a (MD5) Previous issue date: 2011-02-14 / Oilseed rape (Brassica napus L.) belongs to the family Brassicaceae and constitutes the third most produced oilseed in the world, surpassed only by soybean and palm. Flooding of soil and low temperatures can cause alterations in cellular metabolism and impair plant growth, generating a stress condition. Two experiments were conducted using the canola hybrid Hyola 43, Hyola 401, Hyola 420 and Hyola 432. The first was conducted in greenhouse where 10 plants of each hybrid were subjected to stress by flooding for a period of six days. Were evaluated parameters and differences in the kinetics of emission of chlorophyll fluorescence, chlorophyll content, leaf area and dry weight of shoot and root. The flooding caused a reduction of leaf area, root dry mass and root dry mass/shoot dry mass ratio of all hybrids studied. In relation to chlorophyll fluorescence were identified differences in parameters related to specific flows that have undergone changes as a function of stress the latter being more pronounced for Hyola 432. The performace photosynthetic index (PIABS and PIABS,total) showed a decrease after 6 days of the experiment except for hybrid Hyola 420. The analysis of the kinetics of chlorophyll a fluorescence transient showed differential effects of stress application in different sites of photosynthetic apparatus, and these effects were less pronounced in the plants of hybrid Hyola 420. In the second experiment, canola plants were grown in a greenhouse where stress by low temperatures was driven in the Laboratory of Plant Metabolism. Ten plants of each hybrid were placed in a growth chamber the absence of light for different periods of low temperatures: 1 and 4 hours at 0oC and 1, 4 and 15 hours at 4oC. Were evaluated parameters and differences in the kinetics of emission of chlorophyll a fluorescence. The hybrids showed the same behavior in relation to chlorophyll a fluorescence in response to stress by low temperatures. In general, the parameters of chlorophyll fluorescence related to the activity of the PSI were the most affected, and the increase of these parameters resulted in higher values of the PIABS,total. The analysis of the kinetics of chlorophyll a fluorescence transient showed temperature effects, mainly at the J point which reflects the accumulation of reduced plastoquinone (QA -) and the I-P phase reflecting the reduction of end electron acceptors at the PSI acceptor side, ie, ferredoxin (Fd) NADP and other intermediaries. We conclude that the plants of the hibrid Hyola 420 were less affected by flooding showing that this hybrid can be considered less sensitive to stress compared to other hybrids. The parameters that involve the activity of the FSI and the variable fluorescence transient at the J point were more responsive to stress conditions imposed by low temperatures. / A canola (Brassica napus L.) pertence à família das Brassicaceae e constitui-se na terceira oleaginosa mais produzida no mundo, superada apenas pela soja e pela palma. O alagamento do solo e as baixas temperaturas podem promover alterações no metabolismo celular e prejudicar o crescimento das plantas, gerando uma condição de estresse. Foram desenvolvidos dois experimentos utilizando os híbridos de canola Hyola 43, Hyola 401, Hyola 420 e Hyola 432. O primeiro foi conduzido em casa de vegetação, onde 10 plantas de cada híbrido foram submetidas a estresse por alagamento por um período de seis dias. Foram avaliados os parâmetros e as diferenças na cinética de emissão da fluorescência da clorofila, teor de clorofila, área foliar e massa seca da parte aérea e raiz. O alagamento promoveu redução da área foliar, massa seca de raízes e relação massa seca de raiz/massa seca parte aérea de todos híbridos estudados. Em relação a fluorescência da clorofila foram identificadas diferenças nos parâmetros relacionados aos fluxos específicos que sofreram variação em função do estresse sendo esta mais acentuada para Hyola 432. Os índices de performace fotossintéticos (PIABS e PIABS,total) apresentaram decréscimo ao final de 6 dias de experimento exceto para o híbrido Hyola 420. A análise da cinética da fluorescência transiente da clorofila a mostrou efeitos diferenciais da aplicação do estresse nos diferentes locais da maquinaria fotossintética, sendo estes efeitos menos pronunciados nas plantas do híbrido Hyola 420. No segundo experimento as plantas de canola foram cultivadas em casa de vegetação sendo o estresse por baixas temperaturas conduzido no Laboratório de Metabolismo Vegetal. Dez plantas de cada híbrido foram acondicionadas em câmara de crescimento com ausência de luz por períodos distintos de baixas temperaturas: 1 e 4 horas a 0oC e 1, 4 e 15 horas a 4oC. Avaliaram-se os parâmetros e as diferenças na cinética de emissão da fluorescência da clorofila a. Os híbridos apresentaram o mesmo comportamento em relação à fluorescência da clorofila em resposta ao estresse por baixas temperaturas. Em geral, os parâmetros da fluorescência da clorofila relacionados à atividade do fotossistema I foram os mais afetados, sendo que o aumento destes parâmetros resultou em maiores valores de PIABS,total. A análise da cinética da fluorescência transiente da clorofila a revelou efeitos da temperatura principalmente no ponto J o qual reflete o acúmulo de plastoquinona A reduzida (QA -) e na fase I-P que reflete a redução dos aceptores de elétrons finais do lado aceptor do FSI, ou seja, ferredoxina (Fd), outros intermediários e NADP. Conclui-se que as plantas do híbrido Hyola 420 foram menos afetadas pelas condições de alagamento demonstrando que tal híbrido pode ser considerado menos sensível a determinado estresse em relação aos demais híbridos testados. Os parâmetros que envolvem a atividade do FSI bem como a 5 fluorescência variável transiente no ponto J foram mais responsivos às condições impostas pelo estresse por baixas temperaturas.

Made available in DSpace on 2014-08-20T13:59:11Z (GMT). No. of bitstreams: 1 dissertacao_janete_mariza_adamski.pdf: 870957 bytes, checksum: 3780a4713aace89a20cbc46f8e882d7f (MD5) Previous issue date: 2011-02-15 / Iron is an essential element for growth and development of plants and is involved in essential metabolic processes such as photosynthesis and respiration. However, homeostasis of this metal is essential, both excess and deficiency are harmful. One of the characteristic symptoms of deficiency is chlorosis, caused by the decrease in chlorophyll biosynthesis. On the other hand, the free iron in excess can cause oxidative stress. Study of the effects of different concentrations of iron in morphological, physiological or biochemical parameters are essential to a better understanding of this nutrient homeostasis in plants. In the present work, plants of sweet potato were submitted under hydroponics system, to different concentrations of ferric-EDTA in nutrient solution: 0.45; 0.9; 4.5 and 9.0 mmol dm-3. Photosynthetic and growth characteristics, nutrient absorption, antioxidant enzymes, stomatal density and diameter, ultra structure of root and leaves cells and histochemical iron in the leaves were evaluated. The toxicity of iron in excess (9.0 mmol dm-3) led to the appearance of brown spots on leaves, often forming necroses, with significant reductions in growth. In these plants, the activity of superoxide dismutase and ascorbate peroxidase increased. Also, the absorption of other micronutrients was affected mainly of the manganese. The iron content in the shoot increased, also qualitatively confirmed by the histochemical test. The light reactions of photosynthesis were not affected, but there was a decrease in stomatal density and net assimilation rate. The ultra structure of root cells reveals the damage of mitochondria in treatments with high concentrations of iron. However, in these plants, the ultra structure of chloroplasts is not affected. / O ferro é um elemento essencial para o crescimento e desenvolvimento das plantas, estando envolvido em processos metabólicos essenciais, como fotossíntese e respiração. Entretanto, a homeostase desse metal é fundamental, pois tanto o excesso quanto a deficiência são prejudiciais. Um dos sintomas característico da deficiência é a clorose, causada pelo decréscimo na biossíntese da clorofila. Por outro lado, o ferro quando livre e em excesso pode gerar estresse oxidativo. Buscar entender os efeitos de diferentes concentrações de ferro, em nível morfológico, fisiológico ou bioquímico, é indispensável para um melhor entendimento da homeostase desse micronutriente nas plantas. No presente trabalho, plantas de batata-doce foram submetidas, sob sistema de hidroponia, a diferentes concentrações de EDTA-férrico em solução nutritiva: 0,45; 0,9; 4,5 e 9,0 mmol dm-3. Foram avaliadas características fotossintéticas e de crescimento, absorção de nutrientes, atividade de enzimas antioxidantes, densidade e tamanhos dos estômatos, ultra-estrutura de células radiciais e de células da folha e histoquímica do ferro nos tecidos foliares. A toxidez por excesso de ferro (9,0 mmol dm-3) levou ao surgimento de manchas marrons nas folhas, muitas vezes formando necroses, com reduções significativas no crescimento. Nestas plantas, a atividade da superóxido dismutase e ascorbato peroxidase aumentou. Também, a absorção dos demais micronutrientes foi afetada, principalmente do Mn. O teor de ferro na parte aérea aumentou significativamente, sendo visualizado pelo teste histoquímico. As reações luminosas da fotossíntese não foram comprometidas, porém houve queda na densidade estomática e na taxa assimilatória líquida. A ultra-estrutura das células radiciais revela o comprometimento das mitocôndrias nos tratamentos com altas concentrações de ferro. Porém, nestas plantas, a ultra-estrutura dos cloroplastos não é afetada.

Made available in DSpace on 2014-08-20T13:59:14Z (GMT). No. of bitstreams: 1 dissertacao_cristina_moll_huther.pdf: 1943888 bytes, checksum: 19ce036e997295b4526288308a80fe3c (MD5) Previous issue date: 2011-08-10 / The abiotic stress often cause metabolic disorders which cause a decrease in plant growth. In response to stress, an increase in the synthesis of certain proteins called ―heat shock proteins‖ (HSPs), might occur. The tomato (Lycopersicon esculentum) cv. Micro-Tom is regarded as a model for experimental studies, and that is because it has features that make it appropriate, such as small size, short development time and easy modification. This study aimed to evaluate the stress effects by flooding and by high and low temperatures in both modified and not modified ‗Micro-Tom tomato plants which have different mitochondrial expressions (MT- sHSP22). The first experiment was conducted in growth chambers under controlled conditions. When the plants were 50 days, they were submitted to stress by flooding during 14 days, and after 7 days, half the plants were removed from the flooding. In the second trial, plants were grown as in the first experiment, and when they presented themselves in a complete vegetative stage, they were submitted to thermal stress for a period of 24 hours of 10 ºC or 37 °C, soon after that, the plants were transferred to the initial conditions for 24 hours. After this phase they were again subjected to a new cycle of stress and recovery. On both experiments were evaluated parameters of the kinetic emission of chlorophyll fluorescence and of gas exchange, taking into account that in the first was also evaluated the content of chlorophyll, and, at the end of the test, the leaf area and the dry mass of the upper area and root. The flooding interfered on the the chlorophyll content of all genotypes, and on the genotype with a high expression of MT-sHSP22, a decrease in the leaf area was not identified and neither was in the total dry mass. The kinetics analysis of the transient fluorescence of chlorophyll showed differential effects of stress by flooding in the different parts of the photosynthetic machinery, and showed different responses between genotypes. When plants were submitted to stress by low temperature, a reduction in the liquid CO2 rate was noticed immediately after the stress, but, after recovery, all genotypes returned close to the controls. For plants submitted to high temperatures of the wild genotype and with high expression of MT-sHSP22 increased the liquid assimilation rate in comparison to control. The chlorophyll fluorescence data indicated different effects on absorption and utilization of light energy between the two genotypes for two of the temperature stress. The interpretation of the JIP test parameters helped to identify that three genotypes exhibit different behavior, mainly on high-temperature stress, and the plants of high expression genotypes of HSP22 and not transformed showed an increase in the parameters related to the photosystem I activity. These results suggest that plants with high doses of mitochondrial sHSP22 may present mechanisms of tolerance against the applied stress. / Os estresses abióticos geralmente causam disfunções metabólicas que provocam diminuição no crescimento das plantas. Em respostas a estresses pode ocorrer o aumento na síntese de algumas proteínas chamadas proteínas de choque térmico (heat shock proteins, HSPs). O tomate (Lycopersicon esculentum), cv. Micro-Tom é considerado como um modelo para estudos experimentais, pois ele possui características que o tornam adequado, tais como o tamanho pequeno, tempo de geração curto, e facilidade de transformação. Este trabalho teve como objetivo avaliar os efeitos dos estresses por alagamento e por altas e baixas temperatura em plantas transformadas e não transformadas de tomate ‗Micro-Tom com diferentes expressões da sHSP22 mitocondrial (MT-sHSP22). O primeiro experimento foi conduzido em câmaras de crescimento, sob condições controladas. Quando as plantas apresentavam 50 dias foram submetidas a estresse por alagamento por um período de 14 dias, sendo que após 7 dias metade das plantas foram retiradas do alagamento. No segundo ensaio, as plantas foram cultivadas como no primeiro experimento, e quando se apresentavam em estádio vegetativo pleno foram submetidas a estresse térmico por período de 24h a 10ºC ou 37ºC, a seguir as plantas foram transferidas para as condições iniciais por 24h, após este período foram novamente submetidas a um novo ciclo de estresse e recuperação. Em ambos os experimentos foram avaliados os parâmetros da cinética de emissão da fluorescência da clorofila e trocas gasosas, sendo que no primeiro avaliou-se também o índice de clorofila, e ao final do ensaio a área foliar e massa seca da parte aérea e raiz. O alagamento interferiu nos teores de clorofila de todos os genótipos, sendo que no genótipo com elevada expressão da MT-sHSP22, não foi observada redução da área foliar e em relação a massa seca total. A análise da cinética da fluorescência transiente da clorofila a mostrou efeitos diferenciais do estresse por alagamento nos diferentes locais da maquinaria fotossintética, e apresentou variação de resposta entre os genótipos. Quando as plantas foram submetidas ao estresse por baixa temperatura, observou-se redução na taxa assimilatória liquida de CO2 imediatamente após o estresse, mas depois da recuperação todos os genótipos retornaram próximos aos controles. Para as plantas submetidas a altas temperaturas do genótipo selvagem e do com elevada expressão da MT-sHSP22 aumentaram a taxa assimilatória líquida em relação ao controle. Os dados de fluorescência das clorofilas indicaram efeitos diferentes na absorção e aproveitamento da energia luminosa entre os genótipos para os dois estresses de temperatura. A interpretação dos parâmetros do Teste JIP possibilitou identificar que os três genótipos apresentam comportamento distinto principalmente sobre estresse de alta temperatura, sendo que as plantas dos genótipos com alta expressão de sHSP22 e não transformado apresentaram elevação nos parâmetros relacionados a atividade do fotossistema I. Estes resultados sugerem que as plantas com elevada expressão das sHSP22 mitocondrial podem apresentar mecanismos de tolerância frente as estresses aplicados.

Η υδατική καταπόνηση αποτελεί έναν από τους κυριότερους περιβαλλοντικούς παράγοντες περιορισμού της φυτικής ανάπτυξης και απόδοσης στα ξηρά και ημίξηρα οικοσυστήματα, συμπεριλαμβανομένων κι αυτών με μεσογειακού τύπου κλίμα. Σκοπός της παρούσας ερευνητικής εργασίας ήταν η εκτίμηση των επιδράσεων της υδατικής καταπόνησης στη φωτοχημική ικανότητα του PSII και τις φωτεινές αντιδράσεις της φωτοσύνθεσης, σε τυπικά μεσογειακά είδη. Η υδατική καταπόνηση επιτεύχθηκε τόσο εργαστηριακά εντός διαστήματος λίγων ωρών, όσο και σε ημι-φυσικές συνθήκες περιβάλλοντος σε διάστημα περίπου δύο εβδομάδων. Μετά τις δύο εβδομάδες τα φυτά επανυδατώθηκαν, με στόχο την εκτίμηση της ικανότητας ανάκαμψης από το έντονο υδατικό stress. Η ανάλυση της κινητικής της επαγωγής του φθορισμού της χλωροφύλλης a μέσω του JIP-test αποκάλυψε την άμεση επίδραση της έλλειψης νερού στη ροή των ηλεκτρονίων, όπως αυτή εκφράζεται από τις παραμέτρους ψΕο, φΕο, δRo και φRo. Επιπλέον, παρατηρήθηκε αρνητική συσχέτιση του δείκτη RWC με το συνολικό απόθεμα των ενεργών κέντρων του PSI και τους τελικούς υποδοχείς του PSI, καθώς και με τους δείκτες φωτοσυνθετικής απόδοσης PIABS & PItotal. Η μέγιστη φωτοχημική ικανότητα του PSII, φPo(=Fv/Fm) μειώθηκε μόνο σε πολύ χαμηλές τιμές RWC στις εργαστηριακές μετρήσεις που πραγματοποιήθηκαν, ενώ στις ημι-φυσικές συνθήκες η μείωση του φPo την δεύτερη εβδομάδα της υδατικής καταπόνησης συνοδεύτηκε από αυξημένη θερμική απόσβεση της απορροφούμενης ενέργειας διεγέρσεως. Η ανάπτυξη του υδατικού stress σε ημι-φυσικές συνθήκες οδήγησε επίσης στη μεταβολή των ειδικών ενεργειακών ροών ανά δραστικό ενεργό κέντρο του PSII, πιθανώς λόγω της μερικής αδρανοποίησης ενεργών κέντρων στις συνθήκες αυτές. Επιπλέον, καταγράφηκε αύξηση του φθορισμού στα 300 μsec (Σημείο Κ), ένα φαινόμενο που συνδέεται με καταστολή της λειτουργίας του συμπλόκου έκλυσης οξυγόνου. Οι εν λόγω μεταβολές δεν παρατηρήθηκαν στον ίδιο βαθμό στις εργαστηριακές μετρήσεις, γεγονός που πιθανώς οφείλεται στη σταδιακή ανάπτυξη της ξηρασίας και τη συνδυαστική δράση της έλλειψης νερού, της υψηλής θερμοκρασίας και των υψηλών εντάσεων φωτός κάτω από φυσικές συνθήκες περιβάλλοντος. Από την πρώτη κιόλας ημέρα μετά την επανυδάτωση των φυτών, όλες οι παράμετροι του JIP-test άρχισαν να επανακάμπτουν. Ωστόσο, εντοπίστηκαν διαφορές στην ταχύτητα επαναφοράς μεταξύ των διαφορετικών ειδών. Συνολικά, τα ευρήματα μας υποδεικνύουν καταστολή των φωτεινών αντιδράσεων της φωτοσύνθεσης σε συνθήκες υδατικής καταπόνησης, μεταβολή η οποία αντιστράφηκε γρήγορα στα πειράματά μας. Θα μπορούσε λοιπόν, να θεωρηθεί ως ένας μηχανισμός προσαρμογής που εξασφαλίζει στα μεσογειακά είδη που μελετήθηκαν την διατήρηση της λειτουργικότητας της φωτοσυνθετικής συσκευής, ακόμη και σε συνθήκες έντονης υδατικής καταπόνησης. / Water stress is one of the most important environmental factors limiting plant growth and yield in arid and semi-arid ecosystems, including those with Mediterranean climate. The objective of this study was to evaluate the effects of water stress on the photosynthetic capacity of PSII and on the light reactions of photosynthesis of typical Mediterranean species. Water stress experiments were conducted both under laboratory conditions, through dehydration of leaf-disks within hours and under semi-natural conditions by withholding water for about two weeks. Drought period was followed by six days of re-watering, in order to assess the recovery of the photosynthetic apparatus. Analysis of the polyphasic OJIP fluorescence transient through JIP-test, revealed direct limitations in electron transport, as expressed by the parameters ψΕο, φΕο, δRo and φRo. Furthermore, a negative correlation was found between RWC and the pool of the RCs of PSI, the pool of electron end-acceptors, and the photosynthetic efficiency, as expressed by the parameters PIABS & PItotal. The maximum quantum yield of primary photochemistry φPο (=Fv/Fm) was affected only under very low RWC values during the laboratory experiments. On the other hand, a reduction was found during the second week of drought stress treatment, along with an increased conversion rate of absorbed light into thermal energy. Under semi-natural conditions, water stress also caused a shift in the specific energy flows per RC of PSII, caused possibly by inactivation of RCs. Moreover, there was an increase in fluorescence intensity at 300 microseconds (K-band), a phenomenon associated with inhibition of the oxygen evolving complex. These alterations were not observed to the same extent in the laboratory experiments, so they can be attributed to the gradual onset of drought and the combined effect of dehydration, high temperature and high light intensities under natural conditions. Within one day after rehydration, all the parameters of the JIP-test began to recover. However, differences in the recovery rate were observed between different species. In conclusion, our findings indicate down-regulation of light reactions of photosynthesis under water stress. This phenomenon was quickly reversed in our experiments. Therefore, it could be regarded as an adaptive response, which maintains the functionality of the photosynthetic apparatus of the Mediterranean species studied, even under severe water deficit.

Made available in DSpace on 2014-08-20T13:59:10Z (GMT). No. of bitstreams: 1 dissertacao_camila_sousa.pdf: 1105338 bytes, checksum: 6a0e449f6b57375f68a8ff703e00bf3c (MD5) Previous issue date: 2010-10-04 / The objective of this research was: a) evaluate the effect of imidazolinone chemical group herbicides on the growth of plants and the injuries to the photosynthetic apparatus of three rice types (varieties) exposed to these and b) evaluate the effect of soil residual herbicides imazethapyr+ imazapic on corn, cucumber, radish and tomato are used as bioindicators. At first experiments we used the herbicide Only® and Kifix®, using a randomized split plot design in a factorial 5x3 with six replications, with the first factor rates corresponded to 0, 5, 10, 15 and 20 mg p. c. m-2 of commercial product Only® and 0, 7, 14, 21 and 28 mg p. c. m-2 of commercial product Kifix®, and factor B type of rice (cultivated rice cv. Puitá Inta CL, red rice ecotype sensitive to herbicides Imidazolinone and red rice ecotype with suspected herbicide tolerance imidazolinone). We evaluated the parameters of chlorophyll a fluorescence, phytotoxicity, plant height and dry mass. Analysis of chlorophyll a fluorescence was performed using a portable fluorometer (HandyPEA, Hanstech). It was concluded that cv. Puitá Inta CL is tolerant to herbicides Only® and Kifix® and can be used in the Clearfield® system and the red rice ecotype with suspected tolerance was tolerant to both herbicides, suffering a low phytotoxity compared to the sensitive ecotype, even using higher doses of the commercial products. The application of chemical herbicides of the imidazolinone group in rice plants cause changes in the photosynthetic metabolism of plants that can be detected by evaluating the emission of chlorophyll a fluorescence transient. The second experiment was conducted in a randomized block experimental design (with) four replicates per treatment. The treatments were the residual effect of herbicide Only® in rice CL plants in the 2006/2007 harvest, at 0, 10, 15 and 20 mg p. c. m-2 doses of commercial product, on four bioindicators: corn, cucumber, radish and tomato. The variables evaluated were: height, dry weight of shoot and root dry mass, with the latter doesn t being performed for the corn plants. Data of biometric variables generated in both experiments were subjected to analysis of variance (p ≤ 0.05) were significant in these models were tested by polynomial regression. Activity was detected in the commercial mixture of residual herbicides imazethapyr +imazapic in soil 1100 days after herbicide application, by use of bioindicators plants. / Este trabalho teve por objetivo: a) avaliar o efeito da aplicação de herbicidas do grupo químico das imidazolinonas sobre o crescimento de plantas e as injúrias causadas ao aparelho fotossintético de três tipos de arroz e b) avaliar o efeito residual no solo dos herbicidas imazethapyr + imazapic sobre as plantas de milho, pepino, rabanete e tomate, utilizadas como bioindicadoras. No primeiro ensaio foram utilizados os herbicidas Only® e Kifix®, utilizando-se para cada herbicida um delineamento experimental de parcelas subdivididas, em esquema fatorial 5x3, com seis repetições, sendo o fator A as doses do herbicida correspondentes a 0, 5, 10, 15 e 20 mg p. c. m-2 do produto comercial Only® e 0, 7, 14, 21 e 28 mg p. c. m-2 do produto comercial Kifix®, e o fator B o tipo de arroz (arroz cultivado cv. Puitá Inta CL, ecótipo de arroz-vermelho sensível aos herbicidas do grupo das imidazolinonas e ecótipo de arroz-vermelho com suspeita de tolerância aos herbicidas do grupo das imidazolinonas). Foram avaliados os parâmetros da fluorescência da clorofila a, fitotoxicidade, altura de plantas e massa seca da parte aérea. A análise da fluorescência da clorofila a foi realizada utilizando-se um fluorômetro portátil (HandyPEA, Hanstech).Conclui-se que a cv. Puitá Inta CL é tolerante aos herbicidas Only® e Kifix®, podendo ser utilizada no Sistema de Produção Clearfield® e que o ecótipo de arroz-vermelho com suspeita de tolerância apresentou tolerância a ambos herbicidas, sofrendo baixa fitotoxicidade em comparação ao ecótipo sensível, mesmo utilizando-se doses superiores as comerciais dos produtos. A aplicação de herbicidas do grupo químico das imidazolinonas em plantas de arroz causa alterações no metabolismo fotossintético das plantas que podem ser detectadas através da avaliação da emissão da fluorescência da clorofila a transiente. O segundo experimento foi conduzido em um delineamento experimental casualizado por bloco, totalizando quatro repetições por tratamento. Os tratamentos avaliados foram o efeito residual do herbicida Only® sob as plantas de arroz CL na safra 2006/2007, nas doses de doses de 0, 10, 15 e 20 mg p. c. m-2 do produto comercial, sobre quatro espécies bioindicadoras: milho, pepino, rabanete e tomate. Foram avaliadas as variáveis: altura de plantas, massa seca da parte aérea e massa seca das raízes, sendo esta última não realizada para as plantas de milho. Os dados relativos às variáveis biométricas gerados em ambos os experimentos foram submetidos à análise da variância (p≤0,05); em sendo significativos, estes foram testados por modelos de regressão polinomial. Foi detectada atividade residual da mistura comercial dos herbicidas imazethapyr+imazapic em solo após 1100 dias da aplicação dos herbicidas, pelo uso de plantas bioindicadoras.

Made available in DSpace on 2014-08-20T13:59:14Z (GMT). No. of bitstreams: 1 tese_emanuela_garbin_martinazzo.pdf: 992671 bytes, checksum: 8066cbb3845ec759cd326830846dfb28 (MD5) Previous issue date: 2011-11-01 / The growth and development of plants of the rosaceae family present variations of physiological processes during the annual cycle. Plant species that occur over a heterogeneous environment are subject to conditions of multiple stresses due to the variety of weather conditions. In this context, water stress, flooding or deficit, has a profound impact on ecological and agricultural systems. The kinetics of chlorophyll a fluorescence is a quite sensitive to environmental stress, and small changes in structure and operation, can be easily detected by their analysis. This work was divided into three experiments, with the aim of evaluating the variation of the kinetics of chlorophyll fluorescence in the plants of the genus Prunus. The first was conducted in the field, the Centro Agropecuário da Palma, with six treatments (rootstocks) associated with Maciel. They were accompanied by a period of approximately 150 days the length of the leaf chlorophyll content and chlorophyll a fluorescence kinetics. The second and third experiments were conducted in a greenhouse to cultivate plum America (P. salicina) cultivar and hybrid-cup "GxN-9" (P.dulcis Mill. X P.persica L. Batsch) respectively. In both experiments, plants were kept for 11days under water restriction and 10 days of flooding, with three treatments (control, drought and flooding). Analysis of gas exchange and chlorophyll a fluorescence were monitored regularly every three days. During the experiment a variation of fluorescence parameters are affected by ontogeny of the leaves and especially the high rainfall recorded at 97 days of the beginning of the experiment. By analyzing of JIP-Test, damage to the photosynthetic system were checked, along with the best association with Maciel x rootstock Rubirá. In experiment 2, plum plants subjected to water stress, showed a reduction in photosynthesis due to reduced stomatal conductance and the increase in the flow dissipation by reaction center (DI/RC) most striking under conditions of water deficit. In the third experiment, the lowest photosynthetic activity of the hybrid "GxN-9" is related to the decrease in carboxylation efficiency, while the quantum yield of electron transport was more affected by flooding. Thus, the results suggest that plants plum America is growing more sensitive to water deficit conditions, and the rootstock hybrid "GxN-9", the conditions of soil flooding. / O crescimento e o desenvolvimento de plantas da família das rosáceas apresentam variações dos processos fisiológicos durante o ciclo anual. Espécies vegetais que ocorrem ao longo de um ambiente heterogêneo estão sujeitas as condições de múltiplos estresses devido à variedade das condições climáticas. Nesse contexto, o estresse hídrico, por alagamento ou déficit, tem profundo impacto sobre sistemas ecológicos e agrícolas. A cinética da fluorescência da clorofila a, apresenta-se bastante sensível ao estresse ambiental e, pequenas alterações de estrutura e funcionamento, podem ser facilmente detectadas por meio da sua análise. Este trabalho foi dividido em três experimentos, com o objetivo de avaliar a variação da cinética da fluorescência da clorofila a em plantas do gênero Prunus. O primeiro foi conduzido a campo, no Centro Agropecuário da Palma, com seis tratamentos (portaenxertos) associados a cultivar copa Maciel. Foram acompanhadas por um período de aproximadamente 150 dias o comprimento da folha, o índice de clorofila e a cinética da fluorescência da clorofila a. O segundo e terceiro experimento, foram conduzidos em casa de vegetação com a cultivar de ameixeira América (P. salicina) e a cultivar-copa do híbrido GxN-9 (P.dulcis Mill. X P.persica L. Batsch) respectivamente. Em ambos os experimentos, as plantas foram mantidas durante 11 dias sob restrição hídrica e 10 dias de alagamento, totalizando três tratamentos (controle, seca e alagamento do solo). Análise de trocas gasosas e fluorescência da clorofila a, foram acompanhados regularmente a cada três dias. Durante o experimento 1 a variação dos parâmetros de fluorescência sofreu interferência da ontogenia das folhas e principalmente, da alta pluviosidade registrada aos 97 dias do

Made available in DSpace on 2014-08-20T13:59:16Z (GMT). No. of bitstreams: 1 dissertacao_anderson_schock.pdf: 1206821 bytes, checksum: 4f2fc22ec8bca43a2893fc6979ea3727 (MD5) Previous issue date: 2012-02-27 / Among the many species of plants oleaginous plants that have been studied under the proposal to produce biodiesel, the physics nut (Jatropha curcas L.) has emerged due to large percentage of oil contained in seeds and its adaptive capacity, the soil and... / Dentre as muitas espécies de plantas oleaginosas estudadas sob a proposta de produção de biodiesel, a Jatropha curcas L. tem se destacado em função da grande porcentagem de óleo contido nas sementes e de sua capacidade adaptativa...

Η διακυμαινόμενη ασυμμετρία των φύλλων, δηλαδή η τυχαία απόκλιση από τη συμμετρία, θεωρείται ένα μέτρο της καταπόνησης που υπέστησαν κατά την ανάπτυξή τους. Η ασυμμετρία υποδηλώνει αναπτυξιακή αστάθεια και έχει προταθεί ότι συσχετίζεται αρνητικά με την αρμοστικότητα (fitness). Εάν η φωτοσύνθεση αποτελεί έναν έμμεσο δείκτη της αρμοστικότητας, αναμένεται, ένα φύλλο με μειωμένη αρμοστικότητα να είναι και φωτοσυνθετικά υποδεέστερο. Προς επιβεβαίωση αυτού, στην παρούσα διατριβή εξετάστηκαν εκατοντάδες άθικτα φύλλα σε συνολικά 7 διαφορετικά είδη ως προς τη διακυμαινόμενη ασυμμετρία, καθώς και ως προς τη φωτοσυνθετική τους απόδοση (δείκτες PItotal & Fv/Fm). Ο δείκτης PItotal υπολογίζεται με βάση την κινητική ανάλυση των in vivo μεταβολών του φθορισμού της χλωροφύλλης και λαμβάνεται εύκολα και γρήγορα (εντός δευτερολέπτων). Ο δείκτης αυτός θεωρείται ανάλογος της φωτοσυνθετικής αφομοίωσης του CO2 και περιγράφει την απόδοση τόσο του φωτοσυστήματος Ι (PSI) όσο και του φωτοσυστήματος ΙΙ (PSII). Ο παραδοσιακός δείκτης Fv/Fm προκύπτει άμεσα από τις in vivo μετρήσεις φθορισμού της χλωροφύλλης και υποδεικνύει τη μέγιστη φωτοχημική ικανότητα του PSII. Δύο φυτικά είδη (Pistacia lentiscus, Olea europea) επέδειξαν θετική συσχέτιση μεταξύ διακυμαινόμενης ασυμμετρίας και φωτοσυνθετικής ικανότητας, αποτελέσμα αντίθετο από τις αρχικές προβλέψεις. Το μόνο φυτικό είδος που επιβεβαίωσε την αρχική υπόθεση ήταν το Ceratonia siliqua. Στα υπόλοιπα είδη (Arbutus unedo, Cercis siliquastrum, Platanus orientalis, Populus alba) δεν υπήρξε συσχέτιση μεταξύ των δύο παραμέτρων. Τα φυτικά είδη που εμφάνισαν μεγάλες τιμές διακυμαινόμενης ασυμμετρίας ήταν και αυτά στα οποία η ασυμμετρία συχετίστηκε θετικά με τη φωτοσύνθεση. Συμπεραίνεται, εμμέσως ότι η ισχυρή ένταση της καταπόνησης κατά τα πρώιμα στάδια της ανάπτυξης των φύλλων σε μερικά φυτά ενδεχομένως να οδηγεί σε πιο σφριγηλή φωτοσύνθεση κατά την ωριμότητά τους ή σε μεγαλύτερη ικανότητα αντοχής στην καταπόνηση. Αν το συμπέρασμα είναι αληθές, τότε μπορεί μεν η συμμετρία να είναι ομορφότερη, δεν είναι όμως και αποδοτικότερη. Σε γενικές γραμμές, και με βάση τη βιβλιογραφία, ο δείκτης διακυμαινόμενης ασυμμετρίας των φύλλων δεν φαίνεται από μόνος του να επιτυγχάνει αξιόπιστη εκτίμηση της αρμοστικότητας. Για αυτό τον λόγο η χρησιμοποίησή του πρέπει να γίνεται με ιδιαίτερη προσοχή και συνάμα θα πρέπει να συνδυάζεται με σειρά άλλων δεδομένων-δεικτών. Ένας ακόμη δείκτης περιβαλλοντικής καταπόνησης μπορεί να είναι η εποχική συσσώρευση ερυθρών χρωστικών (ανθοκυανινών) που παρατηρείται στα ώριμα φύλλα ορισμένων φυτικών ειδών. Έχει προταθεί ότι οι ανθοκυανίνες των φύλλων λειτουργούν ως «ομπρέλα» προστασίας για τη φωτοσυνθετική συσκευή ενάντια στη φωτοαναστολή. Ως προς την εξέταση αυτής της υπόθεσης, η παρούσα διατριβή χρησιμοποίησε δύο πειραματόφυτα που εμφανίζουν εποχική ερυθρότητα στα φύλλα ορισμένων ατόμων τους. Αυτά είναι το Pistacia lentiscus και το Cistus creticus. Αρχικά όσον αφορά το P. lentiscus, εξετάστηκε η συσχέτιση του βαθμού φωτοπροστασίας με τις πραγματικές συγκεντρώσεις ανθοκυανινών σε φύλλα ατόμων που φύονται σε συνθήκες πεδίου. Το συγκεκριμένο εγχείρημα αποτελεί καινοτομία, αφού μέχρι σήμερα δεν έχει μελετηθεί η φωτοπροστασία σε σχέση με τη διαβάθμιση της ερυθρότητας των φύλλων. Προς αυτή τη κατεύθυνση χρησιμοποιήθηκαν μη επεμβατικές οπτικές μέθοδοι (φάσματα ανακλαστικότητας και φθορισμός χλωροφύλλης) για να αποτιμήσουν τα επίπεδα ανθοκυανινών και χλωροφυλλών καθώς και τη φωτοχημική απόδοση του PS II, σε εκατοντάδες ώριμα φύλλα του φυτικού είδους P. lentiscus (σχίνος). Ο σχίνος κατά τη χειμερινή περίοδο εμφανίζει κόκκινους (όλων των διαβαθμίσεων ερυθρού χρώματος) και πράσινους φαινότυπους. Αντίθετα με την υπόθεση που υποστηρίζει το φωτοπροστατευτικό ρόλο των ανθοκυανινών, η ένταση της ερυθρότητας συσχετίστηκε θετικά με τη φωτοαναστολή και αρνητικά με τα επίπεδα των εμπεριεχόμενων χλωροφυλλών στα φύλλα. Έτσι, ο πιθανός φωτοπροστατευτικός ρόλος των ανθοκυανινών δεν επιβεβαιώθηκε. Ωστόσο, η χειμερινή ερυθρότητα των φύλλων στο σχίνο μπορεί να χρησιμοποιηθεί ως ένας ρεαλιστικός, γρήγορος και μη επεμβατικός τρόπος εντοπισμού ατόμων «ευάλωτων» στη χειμερινή καταπόνηση. Σε μετέπειτα στάδιο στο ίδιο φυτικό είδος, εξετάστηκε in situ η σχέση της χειμερινής ερυθρότητας των φύλλων με σειρά άλλων φωτοσυνθετικών παραμέτρων. Συγκρινόμενοι με τους πράσινους φαινότυπους κατά τη διάρκεια του χειμώνα, οι ερυθροί (ανθοκυανικοί) φαινότυποι παρουσίασαν χαμηλότερες ταχύτητες αφομοίωσης CO2. Βρέθηκε ότι αυτό οφείλεται στη χαμηλή περιεκτικότητα ή/και ενεργότητα του ενζύμου καρβοξυλάση/οξυγονάση της διφωσφορικής ριβουλόζης (Rubisco) των ερυθρών φύλλων, ενώ ταυτόχρονα η στοματική αγωγιμότητα δεν φάνηκε να είναι περιοριστική για τη φωτοσύνθεση. Συγχρόνως, οι ερυθροί φαινότυποι βρέθηκε ότι περιέχουν λιγότερο άζωτο σε σχέση με τους πράσινους. Το εύρημα αυτό πιθανώς συνδέεται με την παρατηρούμενη χαμηλή περιεκτικότητα του ενζύμου Rubisco και τον μειωμένο φωτοσυνθετικό ρυθμό των ερυθρών φύλλων. Η περιορισμένη ικανότητα των αντιδράσεων καρβοξυλίωσης να χρησιμοποιήσουν αναγωγική δύναμη και ηλεκτρόνια, ενδεχομένως εξηγεί και τη μειωμένη απόδοση παγίδευσης φωτονίων του PSII που σημειώνεται στους ερυθρούς φαινοτύπους. Σε οποιαδήποτε περίπτωση, η ανάπτυξη της ανθοκυανικής «ομπρέλας» δεν φαίνεται να αποσοβεί το κίνδυνο φωτοαναστολής της φωτοσύνθεσης στον ερυθρό φαινότυπο του σχίνου. Ως παραπροϊόν της εργασίας με το P. lentiscus, εξετάστηκε η πιθανή επίδραση των φυσικών διακυμάνσεων του αζώτου των φύλλων του στις φωτεινές αντιδράσεις της φωτοσύνθεσης. Συγκεκριμένα, εξετάστηκαν οι φυσιολογικές διακυμάνσεις του αζώτου ώριμων φύλλων σε συνδυασμό με την ανάλυση των αντίστοιχων καμπυλών ταχείας ανόδου του φθορισμού της χλωροφύλλης. Η μαθηματική ανάλυση των καμπυλών έγινε σύμφωνα με το λεγόμενο «JIP-test», γεγονός που επέτρεψε την εκτίμηση της εν δυνάμει δραστηριότητας των δύο φωτοσυστημάτων. Τα αποτελέσματα υπέδειξαν εξάρτηση από την εποχή, επιτρέποντας την εξαγωγή του συμπεράσματος ότι η έλλειψη αζώτου επηρεάζει επιλεκτικά και αρνητικά το PSI, ενώ η αρνητική επίδραση στο PSII περιορίζεται μόνο κατά τη δυσμενή-χειμερινή περίοδο του έτους. Ένας δεύτερος Μεσογειακός θάμνος που εξετάστηκε ήταν το είδος Cistus creticus. Όπως και ο σχίνος, το είδος αυτό επιδεικνύει χαρακτηριστική ενδοειδική ποικιλομορφία στην έκφραση του ανθοκυανικού χαρακτήρα στα φύλλα του. Συγκεκριμένα, μερικά άτομα κοκκινίζουν το χειμώνα, ενώ γειτονικά τους κάτω από τις ίδιες περιβαλλοντικές συνθήκες παραμένουν πράσινα. Η ερυθρότητα των φύλλων διατηρείται μέχρι τα μέσα της άνοιξης. Αυτό το σύστημα απεδείχθη κατάλληλο, όχι μόνο για τη μελέτη του φυσιολογικού ρόλου των ανθοκυανινών αλλά και για τη προσέγγιση οικολογικών ερωτημάτων που σχετίζονται με την αρμοστικότητα (fitness) των δύο φαινότυπων. Επίσης, απεδείχθη πως η φυλλική ερυθρότητα μπορεί να χρησιμοποιηθεί ως ένας οπτικός δείκτης καταπόνησης. Ως τελικές παράμετροι αρμοστικότητας χρησιμοποιήθηκαν, η αναπαραγωγική προσπάθεια ως ο αριθμός ανθέων ανά άτομο, η αναπαραγωγική επιτυχία ως ο αριθμός σπερμάτων ανά άτομο καθώς και η επικονιστική επιτυχία ως ο αριθμός καρπών ανά αριθμό ανθέων και ως ο αριθμός σπερμάτων ανά καρπό. Η μελέτη αυτή, συνδιαζόμενη με σειρά φυσιολογικών δεικτών που εξέτασαν άλλα μέλη της ερευνητικής ομάδας του εργαστηρίου μας έδειξαν ότι, παρόλο που οι φυσιολογικοί δείκτες εμφανίζουν τον ερυθρό φαινότυπο υποδεέστερο, αντίθετα οι αναπαραγωγικοί δείκτες (αποτελέσματα παρούσας διατριβής) δεν παρουσίασαν διαφορές. Εν τέλει, μπορεί ίσως να λεχθεί πως η παρουσία της ερυθρότητας υποδεικνύει μεν «ασθενέστερα» άτομα (που με τη βοήθεια των ανθοκυανινών ίσως επιτυγχάνουν κάποια αντιστάθμιση αυτών των ενδογενών φυσιολογικών και γενετικών αδυναμιών τους), όχι όμως τόσο ασθενικά ώστε να επηρεάζεται αρνητικά η αναπαραγωγική τους επιτυχία και αρμοστικότητα. / Fluctuating asymmetry, small nondirectional deviations from perfect symmetry, has been proposed as a useful indicator of environmental stress. The developmental instability of an organism may induce asymmetric characters. Hence, a high degree of developmental instability, morphologically manifested as fluctuating asymmetry, may indicate less fitness. According to that, less fit individuals are expected to have asymmetric leaves and this may have a negative impact in their photosynthetic yield. In this investigation, fluctuating asymmetry and two photosynthetic indices (PItotal, Fv/Fm) has been measured in a great number of leaves in 7 plant species. PItotal, is an index which expresses the relative photosynthetic performance. It is calculated from the kinetics of fast chlorophyll a fluorescence rise curves according to the so-called «JIP-test». It is considered to be positively correlated to CO2 assimilation rates, hence to productivity based on photosynthesis. Fv/Fm, is a second photosynthetic index which indicates the maximum photosystem II (PSII) photochemical efficiency. Fluctuating asymmetry was positively correlated to both photosynthetic indices in two plant species (Pistacia lentiscus, Olea europea). These results do not support the initial hypothesis of this investigation. Contrary, the species Ceratonia siliqua shows a negative correlation between fluctuating asymmetry and the two photosynthetic indices. Furthermore, in four plant species (Arbutus unedo, Cercis siliquastrum, Platanus orientalis, Populus alba), fluctuating asymmetry and photosynthetic performance were not correlated. It happened that the two species deviating from the initial hypothesis (P. lentiscus and O. europea) display the maximum mean fluctuating asymmetry values among all species included in this investigation. In conclusion, it seems that in some plants whose leaves have experienced high stress as young are more photosynthetically potent as mature. Moreover, these results suggest that the relation between fluctuating asymmetry and photosynthesis is species-specific. Finally, the results show that fluctuating asymmetry may not be a reliable index of developmental instability and stress exposure in plants. Leaf anthocyanins are believed to afford protection against photoinhibition, yet the dependence of protection on actual anthocyanin concentrations has not been investigated. To that aim, non-invasive optical methods (spectral reflectance and chlorophyll fluorescence) were used to assess levels of anthocyanins and chlorophylls as well as photosystem II (PSII) photochemical efficiency in hundreds of leaves from the mastic tree (Pistacia lentiscus). This species displays a continuum of leaf tints during winter from fully green to fully red under field conditions. Contrary to expectations based on the photoprotective hypothesis, the strength of leaf redness was positively correlated to the extent of mid-winter chronic photoinhibition and negatively correlated to leaf chlorophyll contents. Hence, a photoprotective role for anthocyanins is not substantiated. Instead, we argue that winter leaf redness may be used reliably, quickly and non-invasively to locate vulnerable individuals in the field. Given that winter-red leaf phenotypes in the mastic tree are more vulnerable to chronic photoinhibition during the cold season, we asked whether corresponding limitations in leaf gas exchange and carboxylation reactions could also be manifested. During the cold («red») season, net CO2 assimilation rates (A) and stomatal conductances (gs) in the red phenotype were considerably lower than the green phenotype, while leaf internal CO2 concentration (Ci) was higher. The differences were abolished in the «green» period of the year, the dry summer included. Analysis of A versus Ci curves indicated that CO2 assimilation during winter in the red phenotype was limited by Rubisco content and/or activity rather than stomatal conductance. Concomitant to that, leaf nitrogen levels in the red phenotype were considerably lower during the red-leaf period. Hence, we suggest that the inherently low leaf nitrogen levels are linked to the low net photosynthetic rates of the red plants through a decrease in Rubisco content. Accordingly, the reduced capacity of the carboxylation reactions to act as photosynthetic electron sinks may explain the corresponding loss of PSII photon trapping efficiency, which cannot be fully alleviated by the screening effect of the accumulated anthocyanins. In a next step we examined whether leaf nitrogen level affects photosynthetic light reactions. Although it is amply documented that CO2 assimilation rates are positively correlated to leaf nitrogen, corresponding studies on a link between this nutrient and photosynthetic light reactions are scarce, especially under natural field conditions. In this final investigation with mastic tree, we exploited natural variation in nitrogen content of mature leaves of P. lentiscus in conjunction with fast chlorophyll a fluorescence rise (the OJIP curves) analysed according to the so-called «JIP-test», as this was recently modified to allow also for the assessment of events in or around photosystem I (PSI). The results depended on the sampling season, with low nitrogen leaves displaying lower efficiencies for electron flow from intermediate carriers to final PSI acceptors and lower relative pool sizes of these acceptors, both during the autumn and winter. However, parameters related to the PSII activity (i.e. quantum yields for photon trapping and electron flow along PSII, efficiency of a trapped exciton to move an electron from QA- to intermediate carriers) were limited by low nitrogen only during the winter period. As a result, parameters like the quantum yield of total electron flow along both photosystems as well as the total photosynthetic performance index (PItotal) were positively correlated to leaf nitrogen independently of season. We conclude that nitrogen deficiency under field conditions preferentially affects PSI activity while the effects on PSII are evident only during the stressful period of the year. In the last part of this dissertation we asked whether the leaf anthocyanic trait confers long term benefits to the plant and to that aim parameters directly related to fitness, i.e. reproductive effort and success as well as seed germinability were registered in winter-red and green phenotypes of Cistus creticus growing in the field under apparently similar conditions. The results indicated that both phenotypes displayed similar flower numbers, pollination success and seed yield, mass and germinability. As judged by the similar final reproductive output, vulnerability to the winter stress does not render the red phenotype less fit, nor anthocyanin accumulation render it more fit. Although an apparent compensating function for anthocyanins may be inferred, it can not be linked to a protection against photoinhibition of photosynthesis. Moreover, the photosynthetic inferiority of the red phenotype although linked to slightly reduced leaf number, (results from other members of our laboratory) it was not limiting for reproductive effort and success. Regardless of function, winter leaf redness may indicate photosynthetically weak, yet not necessarily less fit individuals in C. creticus.

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