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Η εκτίμηση της παραγωγικότητας των χερσαίων οικοσυστημάτων προϋποθέτει τη δημιουργία αξιόπιστων μοντέλων παραγωγικότητας. Τα μοντέλα παραγωγικότητας τροφοδοτούνται με μια σειρά βιοτικών (φωτοσυνθετική ταχύτητα, συγκέντρωση χλωροφύλλης, ειδική μάζα φύλλου) και αβιοτικών παραμέτρων (θερμοκρασία, ένταση φωτός, βροχόπτωση) των φυτικών ειδών και του περιβάλλοντος. Μία από τις σημαντικότερες βιοτικές παραμέτρους αποτελεί η μέγιστη φωτοσυνθετική ταχύτητα κάτω από κορεσμένες εντάσεις φωτός, σε φυσιολογικές συγκεντρώσεις CO2 και στις επικρατούσες θερμοκρασίες (Asat). Η μέτρηση της Asat στο πεδίο με τις κλασσικές μεθόδους (αναλυτής αερίων) είναι επίπονη και χρονοβόρος διαδικασία. Για το λόγο αυτό νέοι τρόποι υπολογισμού της Asat προτείνονται. Στην παρούσα εργασία διερευνήθηκε η δυνατότητα εκτίμησης της Asat ορισμένων μεσογειακών φυτών μέσω της ανάλυσης της ταχείας φάσης ανόδου του φθορισμού της χλωροφύλλης (JIP-test). Για το σκοπό αυτό χρησιμοποιήθηκαν τα ετήσια είδη Malva sylvestris και Capparis spinosa, το φυλλοβόλο είδος Cercis siliquastrum, το ημιφυλλοβόλο είδος Phlomis fruticosa, και τα σκληρόφυλλα είδη Nerium oleander, Ceratonia siliqua και Ligustrum japonicum. Οι μετρήσεις της Asat πραγματοποιήθηκαν με τη χρήση αναλυτή αερίων ανοικτού τύπου (LI-6400, LICOR), ενώ για τη μέτρηση της ταχείας φάσης ανόδου του φθορισμού χρησιμοποιήθηκε φθορισμόμετρο υψηλής χρονικής ανάλυσης (HandyPEA, Hansatech). Οι μετρήσεις πραγματοποιήθηκαν σε εποχιακή βάση. Σύμφωνα με τα αποτελέσματα των πειραμάτων μας, δεν βρέθηκε κάποια παράμετρος του JIP-test που μπορεί να χρησιμοποιηθεί ως γενικευμένος δείκτης της Asat, αντίθετα η Asat εμφάνισε πολύ καλή συσχέτιση με τη στοματική αγωγιμότητα. Εντούτοις, στα σκληρόφυλλα είδη και το ημιφυλλοβόλο είδος βρέθηκε καλή συσχέτιση μεταξύ της Asat και των δεικτών ψΕ0, δR0 και φR0 για τα χειμερινή ομάδα μετρήσεων. Η δυσμενέστερη περίοδος για τα πολυετή είδη φαίνεται πως είναι το καλοκαίρι. Τέλος, ο δείκτης VK/VJ μπορεί να υποδείξει τις κύριες καταπονητικές περιόδους. / The evaluation of the productivity of terrestrial ecosystems presupposes the creation of reliable productivity models. The productivity models are supplied with a series of biotic (photosynthetic rate, chlorophyll concentration, specific leaf mass) and abiotic parameters (temperature, light intensity, rainfall) of the plant species and of the environment. One of the most important biotic parameters is the maximum photosynthetic rate under saturated light intensities, under ambient CO2 concetration and under the prevailing temperatures (Asat). The measurement of Asat under field conditions using the traditional methods (gas analyzer) is a laborious and time consuming process. For this reason new methods of Asat calculation are suggested. In the present study the possibility of Asat estimation in some Mediterranean species with the use of the fast chlorophyll fluorescence transient (JIP-test) has been examined. For this purpose, the annual species Malva sylvestris and Capparis spinosa, the deciduous species Cercis siliquastrum, the semi-deciduous species Phlomis fruticosa, and the sclerophyllous species Nerium oleander, Ceratonia siliqua και Ligustrum japonicum have been used. The Asat measurements have been carried out with the use of an open gas exchange analyzer (LI-6400, LICOR), while for the measurement of the fast chlorophyll fluorescence transient a high-time resolution fluorometer (HandyPEA, Hansatech) has been used. The measurements were carried out on a seasonal basis. According to the results of our experiments, no JIP-test parameter has shown to act as a generalized index of Asat, while Asat has shown a very good correlation with stomatal conductance. However, at the sclerophyllous and the semi-deciduous species, a good correlation between Asat and ψΕ0, δR0 και φR0 indices has been shown for the winter team. The most adverse period of the year for the perennial species is summer. Finally, VK/VJ index is indicative of the most stressful periods for our species.

MORAIS NETO, Luiz Barreto de. Avaliação temporal do acúmulo de fitomassa e trocas gasosas do capim-canarana em função da salinidade da água de irrigação. 2009. 58 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Zootecnia, Fortaleza-CE, 2009 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-04T13:07:21Z No. of bitstreams: 1 2009_dis_lbmoraisneto.pdf: 703748 bytes, checksum: 8d09fadb2c87430e9b87f81738fcd1e1 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-04T13:07:51Z (GMT) No. of bitstreams: 1 2009_dis_lbmoraisneto.pdf: 703748 bytes, checksum: 8d09fadb2c87430e9b87f81738fcd1e1 (MD5) / Made available in DSpace on 2016-08-04T13:07:51Z (GMT). No. of bitstreams: 1 2009_dis_lbmoraisneto.pdf: 703748 bytes, checksum: 8d09fadb2c87430e9b87f81738fcd1e1 (MD5) Previous issue date: 2009 / This study was conducted to evaluate the effect of saline irrigation water and different cut times on the components of biomass, gas exchange, growth and yield of canarana grass (Echinochloa pyramidalis). The seedlings were planted in plastic pots with a volume of 8 L containing soil type QUARTZARENIC NEOSOL sandy texture, under conditions of a greenhouse. For the experiment in which we evaluated the components of biomass, the experimental design was completely casualized sub divided plots, the salinity levels (0.75, 2.0, 4.0, 6.0 and 8.0 dS m-1) in the main plots and harvest age (21, 28, 35, 42 and 49 days) in the plot, with five replicates and the experiment was evaluated gas exchange, growth and production, randomized design, in a 5 x 5, consists of cutting ages (21, 28, 35, 42 and 49 days) and five doses saline water (0.75, 2.0, 4.0, 6.0 and 8.0 dS/m) with five replications. After the cut for uniformity, 56 days after the planting began the treatments. Upon reaching the age cutoff determined, the plants were cut and then the material collected was fractionated into leaves, stems and dead material. It was determined the mass of dry total forrage, dry matter of forage dead, dry mass of live forrage, dry matter of green blade, dry mass of green stem, material relationship alive matter/dead material and leaf/stem. Salinity affected the photosynthetic rates and transpiration rates, but did not affect stomatal conductance. There was tolerance to salt stress in each section. There was no interaction between the factors studied. Salinity reduced the dry mass of total herbage, dry forrage of green, dry blade green and dry mass of stem green. There was no effect of salinity on dry mass of dead forrage, live material for dead plant material and leaf/stem. The salinity changed the partition of dry matter, reducing the percentage of stems and increasing the proportion of leaves in the dry mass of total forrage. The increase of the cut caused increases in dry mass of total forrage, dead forrage, live forrage, green stems and green leaves. From the cutting age of 28 days of dry forrage dead had increased quite markedly. The increase in dry weight of stems was accentuated after 35 days. The extension of the cut caused a decline in relations material living dead plant material and leaf/stem. Salinity affected the photosynthetic rates and transpiration, but did not affect stomatal conductance. Climatic variations in the different days on which the measurements were made of gas exchange, caused differences in photosynthetic rate, transpiration rate and stomatal conductance. Climatic variations in the different days on which the measurements were made of gas exchange, caused differences in photosynthetic rate, transpiration rate and stomatal conductance. Salinity did not cause variations in specific leaf area, leaf weight and leaf area ratio, but these three variables decreased with increasing age. The tolerance to salt stress decreased with advancing age. This species was moderately tolerant to higher salinity level and longer exposure to stress. The canarana grass can be irrigated with water electrical conductivity of up to 2.0 dS/m. Cutting canarana grass should be done at 21 days / O trabalho foi conduzido com o objetivo de avaliar o efeito da salinidade da água de irrigação e de diferentes idades de corte sobre os componentes de biomassa, trocas gasosas, crescimento e produção de do capim-canarana (Echinochloa pyramidalis). As mudas foram plantadas em vasos plásticos com volume de 8 L contendo solo do tipo NEOSSOLO QUARTIZARÊNICO textura arenosa, sob condições de casa de vegetação. Para o experimento em que se avaliou os componentes de biomassa, o delineamento utilizado foi inteiramente casualizado em parcelas subdividida, sendo os níveis de salinidade (0,75; 2,0; 4,0; 6,0 e 8,0 dS m-1) na parcela principal e idade de corte (21, 28, 35, 42 e 49 dias) na subparcela, com cinco repetições e para o experimento que se avaliou as trocas gasosas, crescimento e produção, o delineamento foi inteiramente casualizado, em esquema fatorial 5 x 5, composto por cinco idades de corte (21, 28, 35, 42 e 49 dias) e cinco doses crescentes de água salina (0,75, 2,0 , 4,0, 6,0 e 8,0 dS/m), com cinco repetições. Após o corte de uniformização, 56 dias posterior ao plantio, iniciou-se a aplicação dos tratamentos. Ao atingir a idade de corte determinada, as plantas foram cortadas e em seguida o material coletado foi fracionado em folhas, colmos e material morto. Determinou-se a massa seca de forragem total, massa seca de forragem morta, massa seca de forragem viva, massa seca de lâmina verde, massa seca de colmo verde, relação material vivo/material morto e relação folha/colmo. Foram realizadas quatro medições da taxa fotossintética líquida, taxa de transpiração e condutância estomática. Para cada idade foi determinada a área foliar específica, razão de peso foliar e razão de área foliar. Verificou-se a tolerância ao estresse salino em cada corte. Não houve interação entre os fatores estudados. A salinidade reduziu a massa seca de forragem total, massa seca de farragem verde, massa seca de lâmina verde e a massa seca de colmo verde. Não se verificou efeito da salinidade sobre a massa seca de forragem morta, relação material vivo/material morto e relação folha/colmo. A salinidade alterou a partição de matéria seca, diminuindo a percentagem de colmos e aumentando a percentagem de folhas na massa seca de forragem total. O aumento da idade de corte ocasionou aumentos na massa seca de forragem total, forragem morta, forragem viva, colmos verdes e folhas verdes. A partir da idade de corte de 28 dias a massa seca de forragem morta teve incremento bastante acentuado. O aumento na massa seca de colmos acentuou-se a partir dos 35 dias. O prolongamento da idade de corte provocou um declínio nas relações material vivo/material morto e folha/colmo. A salinidade afetou as taxas fotossintética e de transpiração, mas não afetou a condutância estomática. As variações climáticas ocorridas nos diferentes dias em que foram feitas as medições de trocas gasosas, provocaram diferenças na taxa fotossintética, taxa de transpiração e condutância estomática. A salinidade não causou variações na área foliar específica, razão de peso foliar e razão de área foliar, no entanto estas três variáveis decresceram com o aumento da idade. A tolerância ao estresse salino diminuiu com o avanço da idade. Esta espécie mostrou-se moderadamente tolerante ao maior nível de salinidade e no maior tempo de exposição ao estresse. O capim canarana pode ser irrigado com água de condutividade elétrica de até 2,0 dS/m. O corte do capim canarana deve ser feito aos 21 dias

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O trabalho foi conduzido com o objetivo de avaliar o efeito da salinidade da Ãgua de irrigaÃÃo e de diferentes idades de corte sobre os componentes de biomassa, trocas gasosas, crescimento e produÃÃo de do capim-canarana (Echinochloa pyramidalis). As mudas foram plantadas em vasos plÃsticos com volume de 8 L contendo solo do tipo NEOSSOLO QUARTIZARÃNICO textura arenosa, sob condiÃÃes de casa de vegetaÃÃo. Para o experimento em que se avaliou os componentes de biomassa, o delineamento utilizado foi inteiramente casualizado em parcelas subdividida, sendo os nÃveis de salinidade (0,75; 2,0; 4,0; 6,0 e 8,0 dS m-1) na parcela principal e idade de corte (21, 28, 35, 42 e 49 dias) na subparcela, com cinco repetiÃÃes e para o experimento que se avaliou as trocas gasosas, crescimento e produÃÃo, o delineamento foi inteiramente casualizado, em esquema fatorial 5 x 5, composto por cinco idades de corte (21, 28, 35, 42 e 49 dias) e cinco doses crescentes de Ãgua salina (0,75, 2,0 , 4,0, 6,0 e 8,0 dS/m), com cinco repetiÃÃes. ApÃs o corte de uniformizaÃÃo, 56 dias posterior ao plantio, iniciou-se a aplicaÃÃo dos tratamentos. Ao atingir a idade de corte determinada, as plantas foram cortadas e em seguida o material coletado foi fracionado em folhas, colmos e material morto. Determinou-se a massa seca de forragem total, massa seca de forragem morta, massa seca de forragem viva, massa seca de lÃmina verde, massa seca de colmo verde, relaÃÃo material vivo/material morto e relaÃÃo folha/colmo. Foram realizadas quatro mediÃÃes da taxa fotossintÃtica lÃquida, taxa de transpiraÃÃo e condutÃncia estomÃtica. Para cada idade foi determinada a Ãrea foliar especÃfica, razÃo de peso foliar e razÃo de Ãrea foliar. Verificou-se a tolerÃncia ao estresse salino em cada corte. NÃo houve interaÃÃo entre os fatores estudados. A salinidade reduziu a massa seca de forragem total, massa seca de farragem verde, massa seca de lÃmina verde e a massa seca de colmo verde. NÃo se verificou efeito da salinidade sobre a massa seca de forragem morta, relaÃÃo material vivo/material morto e relaÃÃo folha/colmo. A salinidade alterou a partiÃÃo de matÃria seca, diminuindo a percentagem de colmos e aumentando a percentagem de folhas na massa seca de forragem total. O aumento da idade de corte ocasionou aumentos na massa seca de forragem total, forragem morta, forragem viva, colmos verdes e folhas verdes. A partir da idade de corte de 28 dias a massa seca de forragem morta teve incremento bastante acentuado. O aumento na massa seca de colmos acentuou-se a partir dos 35 dias. O prolongamento da idade de corte provocou um declÃnio nas relaÃÃes material vivo/material morto e folha/colmo. A salinidade afetou as taxas fotossintÃtica e de transpiraÃÃo, mas nÃo afetou a condutÃncia estomÃtica. As variaÃÃes climÃticas ocorridas nos diferentes dias em que foram feitas as mediÃÃes de trocas gasosas, provocaram diferenÃas na taxa fotossintÃtica, taxa de transpiraÃÃo e condutÃncia estomÃtica. A salinidade nÃo causou variaÃÃes na Ãrea foliar especÃfica, razÃo de peso foliar e razÃo de Ãrea foliar, no entanto estas trÃs variÃveis decresceram com o aumento da idade. A tolerÃncia ao estresse salino diminuiu com o avanÃo da idade. Esta espÃcie mostrou-se moderadamente tolerante ao maior nÃvel de salinidade e no maior tempo de exposiÃÃo ao estresse. O capim canarana pode ser irrigado com Ãgua de condutividade elÃtrica de atà 2,0 dS/m. O corte do capim canarana deve ser feito aos 21 dias / This study was conducted to evaluate the effect of saline irrigation water and different cut times on the components of biomass, gas exchange, growth and yield of canarana grass (Echinochloa pyramidalis). The seedlings were planted in plastic pots with a volume of 8 L containing soil type QUARTZARENIC NEOSOL sandy texture, under conditions of a greenhouse. For the experiment in which we evaluated the components of biomass, the experimental design was completely casualized sub divided plots, the salinity levels (0.75, 2.0, 4.0, 6.0 and 8.0 dS m-1) in the main plots and harvest age (21, 28, 35, 42 and 49 days) in the plot, with five replicates and the experiment was evaluated gas exchange, growth and production, randomized design, in a 5 x 5, consists of cutting ages (21, 28, 35, 42 and 49 days) and five doses saline water (0.75, 2.0, 4.0, 6.0 and 8.0 dS/m) with five replications. After the cut for uniformity, 56 days after the planting began the treatments. Upon reaching the age cutoff determined, the plants were cut and then the material collected was fractionated into leaves, stems and dead material. It was determined the mass of dry total forrage, dry matter of forage dead, dry mass of live forrage, dry matter of green blade, dry mass of green stem, material relationship alive matter/dead material and leaf/stem. Salinity affected the photosynthetic rates and transpiration rates, but did not affect stomatal conductance. There was tolerance to salt stress in each section. There was no interaction between the factors studied. Salinity reduced the dry mass of total herbage, dry forrage of green, dry blade green and dry mass of stem green. There was no effect of salinity on dry mass of dead forrage, live material for dead plant material and leaf/stem. The salinity changed the partition of dry matter, reducing the percentage of stems and increasing the proportion of leaves in the dry mass of total forrage. The increase of the cut caused increases in dry mass of total forrage, dead forrage, live forrage, green stems and green leaves. From the cutting age of 28 days of dry forrage dead had increased quite markedly. The increase in dry weight of stems was accentuated after 35 days. The extension of the cut caused a decline in relations material living dead plant material and leaf/stem. Salinity affected the photosynthetic rates and transpiration, but did not affect stomatal conductance. Climatic variations in the different days on which the measurements were made of gas exchange, caused differences in photosynthetic rate, transpiration rate and stomatal conductance. Climatic variations in the different days on which the measurements were made of gas exchange, caused differences in photosynthetic rate, transpiration rate and stomatal conductance. Salinity did not cause variations in specific leaf area, leaf weight and leaf area ratio, but these three variables decreased with increasing age. The tolerance to salt stress decreased with advancing age. This species was moderately tolerant to higher salinity level and longer exposure to stress. The canarana grass can be irrigated with water electrical conductivity of up to 2.0 dS/m. Cutting canarana grass should be done at 21 days

Many coastal plant species thrive across a range of environmental conditions, often displaying dramatic phenotypic variation in response to environmental variation. We characterized the response of the critical foundation species Rhizophora mangle L. to full factorial combinations of salt and nitrogen (N). We used seedlings collected from five populations and measured traits related to salt tolerance and N amendment. The response to increasing salt included significant plasticity in succulence, leaf mass area (LMA), and root to shoot ratio (R:S). Seedlings also showed overall reduced maximum photosynthetic rate in response to N amendment, but this response depended on the level of salt and varied by site of origin of the seedlings. Seedlings from different sites also differed in height growth, LMA, R:S, and total dry biomass. Generally, survival was lower in high salt and high N, but the impact varied among sites. Overall, this study revealed significant trait plasticity in response to salt and N level, and differentiation of responses of seedlings among different sites. Seedling survival depended on maternal family for 3 of 5 sites showing variation within and among sites. Variation in trait plasticity and seedling survival in R. mangle may be important for future adaptation to a complex mosaic of environmental conditions.

Resumo: A cana-de-açúcar (Saccharum spp.) é uma das principais culturas das regiões tropicais, cuja produtividade agrícola pode ser afetada pelo déficit hídrico. Para investigar o processo de tolerância e sensibilidade ao déficit hídrico, diferentes parâmetros fisiológicos foram avaliados em cultivares de cana-de-açúcar tolerantes (SP83-2847 e CTC15) e sensível (SP86-155) ao déficit hídrico. A deficiência hídrica afetou todo o aparato fotossintético das plantas de forma diferenciada dentro e entre as cultivares. A taxa fotossintética e condutância estomática diminuíram significativamente para todas as cultivares submetidas ao estresse. Nas plantas controle das cultivares (cv) tolerantes SP83-2847 e CTC15 observou-se que a taxa fotossintética apresentou valores mais altos em comparação a cultivar sensível SP86-155. Resultados do teor relativo de água mostraram que a cultivar CTC15 apresentou melhor condição hídrica durante o período de déficit hídrico. A eficiência quântica do fotossistema II da cultivar SP83-2847 mostrou maior estabilidade nos últimos dias do tratamento experimental, sugerindo que o decréscimo do teor relativo de água estimulou o ajuste da capacidade fotossintética frente às alterações da disponibilidade hídrica. De modo geral, as cultivares SP83-2847 e CTC15, consideradas tolerantes, sob déficit hídrico exibiram melhor desempenho em relação a cultivar sensível SP86-155. Os dados permitem sugerir que tais parâmetros fisiológicos podem ser empregados na avaliação e distinção de genótipos de cana-de-açúcar tolerantes e sensíveis ao déficit hídrico. / Abstract: The sugarcane (Saccharum spp.) is one of the main crops cultivated in tropical areas, whose agricultural productivity can be affected by drought. To investigate the tolerance and sensitivity process to water deficit, various physiological parameters were evaluated in sugarcane cultivars considered tolerant (SP83-2847 and CTC15) and sensitive (SP86-155) to drought. The water deficit affected the entire photosynthetic apparatus of all plants in different manners, inside and among cultivars. The photosynthetic rate and stomatal conductance decreased significantly for all cultivars, submitted to water stress. In control plants of the tolerant cultivars SP83-2847 and CTC15, it was observed that the photosynthetic rate showed better values in comparison to sensitive cultivar SP86-155. According to relative water content results of the cultivar CTC15 showed better condition water performance during the drought. The quantum efficiency photosystem II of the cultivar SP83-2847 showed greater stability in recent days of the experimental treatment, suggesting that the decline in the relative water content stimulated the adjustment of photosynthetic capacity to face the changes in water availability. Thus, cultivars SP83-2847 and CTC15, considered tolerant under water deficit, showed better performance in comparison to sensitive cultivar SP86-155. The data suggest that these physiological parameters can be used in the evaluation and distinction of drought tolerant and sensitive sugarcane genotypes. / Orientador: Sonia Marli Zingaretti / Coorientador: Clara Beatriz Hoffmann-Campo / Banca: Rinaldo Cesar de Paula / Banca: José Renato Bouças Farias / Mestre

Orientador: Marlene Aparecida Schiavinato / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-11T08:26:31Z (GMT). No. of bitstreams: 1 PinzonTorres_JavierAlberto_D.pdf: 1532904 bytes, checksum: 9f5bb662cffba52fd08c58de00484c25 (MD5) Previous issue date: 2008 / Resumo: As grandes quantidades de poluentes gasosos que as áreas urbano-industriais emitem contribuem para a degradação de ecossistemas com subseqüentes declínios na vegetação. A fotossíntese é um dos primeiros processos alterados pela ação destes poluentes e o dióxido de enxofre (SO₂), por ser um dos poluentes aéreos mais freqüentes e nocivos, afeta drasticamente a atividade fotossintética e causa graves injúrias nos tecidos foliares. O SO₂ difunde-se tão prontamente quanto o CO₂ para o interior da folha através dos estômatos e, na fase aquosa da câmara subestomática, se solubiliza formando bisulfito e sulfito, que são espécies iônicas de ação oxidante altamente agressiva para a célula. O sulfito, se não for rapidamente oxidado para sulfato em presença da luz, compete com o CO₂ tornando-se um inibidor da fixação fotossintética, enquanto que o bisulfito pode reagir com aldeídos e cetonas, formando hidroxisulfonatos, que são inibidores de várias enzimas. Durante a oxidação aeróbica dos sulfitos e bisulfitos há aumento da concentração de radicais livres que, se não forem exauridos rapidamente por enzimas de destoxificação, podem causar peroxidação dos ácidos graxos insaturados, ruptura dos lipídeos hidroperóxidos e co-oxidação das clorofilas nos cloroplastos. A resistência da planta à ação tóxica do SO₂ sugere vários mecanismos, dentre as quais se destacam: a redução da absorção de SO₂ por meio do fechamento estomático; a oxidação do sulfito a sulfato com posterior armazenamento do sulfato no vacúolo e incorporação ao metabolismo normal sob forma orgânica; e a eliminação pelo sistema antioxidante das peroxidases e da superóxido dismutase. Se um excesso de enxofre é absorvido e a concentração de tióis aumenta, o enxofre poderá ser acumulado na forma de glutationa, que é um tripeptídeo com uniões sulfídricas, ou os excessos de grupos sulfídricos e sulfitos poderiam ser convertidos em sulfetos ou perdidos na forma de ácido sulfídrico, por meio de trocas gasosas, retirando enxofre do metabolismo da planta. O objetivo do trabalho foi estudar os mecanismos imediatos de defesa e recuperação da taxa fotossintética em plantas de Centrolobium tomentosum sob condições de estresse induzido por SO₂, antes que algum tipo de injúria foliar ou fitotoxicidade, como clorose ou necrose foliar, se tornassem visíveis. Para isto, uma câmara de indução foi especialmente construída, de modo a permitir coletar amostras foliares in vivo, enquanto o estresse estava acontecendo. Dentro da câmara de indução foi colocada uma espécie nativa, Centrolobium tomentosum, que havia sido mantida até então sob condições ambientais naturais, na casa de vegetação do Departamento de Fisiologia Vegetal (Unicamp). Os ensaios com SO₂ foram realizados na câmara de indução, em sistema fechado, e esta foi mantida em uma câmara de crescimento, sob condições controladas de luz, temperatura e umidade. Plantas de C. tomentosum entre oito meses e um ano de idade foram submetidas a diferentes concentrações de SO₂ com a finalidade de determinar a concentração mínima de SO₂ capaz de induzir, na taxa fotossintética, a sucessão das fases características de uma dinâmica de estresse. Foram utilizadas cinco plantas diferentes por cada concentração de SO₂ aplicada e registrou-se a taxa fotossintética utilizando um Sistema Portátil de Análise de Gases por Infravermelho (IRGA). Nas mesmas folhas foram analisados antioxidantes do tipo não enzimático (pigmentos fotossintéticos e ácido ascórbico) e antioxidantes do tipo enzimático (superóxido dismutase e glutationa redutase). Foi determinado que a concentração mínima para induzir a dinâmica de estresse em plantas de C. tomentosum foi de 258,07 g SO₂ m­­­ֿ³, que equivale a uma concentração muito alta com relação às concentrações máximas recomendadas pelas organizações governamentais para o controle de poluição de ar. A sucessão de fases na taxa fotossintética foram as seguintes: - Taxa fotossintética antes da aplicação do SO&#8322: nesta fase, a taxa fotossintética registrou uma média de 4,4 μmol CO&#8322 m­­­­­ֿ² s­­­­­ֿ¹. Foram tomadas amostras foliares, cujas análises corresponderam ao controle. - Fase de alarme: iniciada imediatamente após a aplicação de 258,07 g SO₂ m­­­ֿ³ e caracterizada por uma queda abrupta na taxa fotossintética de 92%. Posteriormente, veio o estresse propriamente dito, com registros muito baixos na taxa fotossintética. - Fase de restituição: na qual se observou a recuperação paulatina da taxa fotossintética. Fase de resistência: na qual, após 9 h da exposição ao SO₂, a taxa fotossintética registrou recuperação de 50%. Após 24 h do ensaio ter sido iniciado, a taxa fotossintética registrou os valores iniciais correspondentes ao controle, ou seja, uma recuperação completa. Em todas as fases, com exceção da fase de restituição, foram tomadas amostras foliares. Não foram observados sintomas de clorose ou necrose nas folhas de C. tomentosum após a exposição ao SO₂ e as análises químicas dos pigmentos fotossintéticos corroboram esta observação. Porém, nas fases de estresse e de recuperação completa, os teores de carotenóides aumentaram com relação ao controle. O incremento do ácido ascórbico teve a mesma tendência do que o dos carotenóides nas fases de estresse e de recuperação completa. A atividade da superóxido dismutase aumentou significativamente na fase de estresse, enquanto que a atividade da glutationa redutase aumentou significativamente na fase de recuperação completa. A dinâmica de estresse e o mecanismo imediato de destoxificação em plantas de C. tomentosum submetidas a 258,07 g SO₂ m­­­ֿ³ sugerem que efetivamente houve um estresse oxidativo, que foi superado da seguinte maneira: na fase de alarme, o sulfito reagiu com a ribulose bisfosfato antes que fosse foto-oxidado para sulfato. Isto explica a inibição da carboxilação, com a queda abrupta da taxa fotossintética. Os oxi-radicais livres citotóxicos gerados nos cloroplastos, como conseqüência da foto-oxidação dos sulfitos, foram exauridos rapidamente pelo aumento, na fase de estresse, dos carotenóides e do ácido ascórbico e pelo aumento da atividade da superóxido dismutase. Porém, o enxofre proveniente do SO₂ não foi imediatamente acumulado na forma de glutationa. Isso somente ocorreu quando a planta recuperou completamente a taxa fotossintética. Desta maneira, verificou-se que C. tomentosum é uma espécie resistente que poderia ser utilizada em espaços onde as emissões de SO₂ são altas, como nas indústrias químicas, petroquímicas, siderúrgicas e de fertilizantes, dentre outras. / Abstract: Large quantities of gaseous pollutants emited by urban-industrial areas emit contribute to the degradation of ecosystems with subsequent declines in vegetation. The photosynthesis is one of the first processes altered by the action of these pollutants and sulphur dioxide (SO₂), as one of the most common and harmful air pollutants, drastically affect the photosynthetic activity and cause serious injuries in the leaf tissue. The SO₂ diffuses itself as promptly as the CO₂ into the leaf through the stomata, and in the aqueous phase of the substomatal cavity it solubilizes forming bisulphite and sulphite, which are ionic species of highly aggressive oxidant action to the cell. Sulphites, if it is not quickly oxidized to sulphate in the presence of light, it competes with CO₂ becoming an inhibitor of photosynthetic fixation, while the bisulphite can react with aldehydes and ketones, forming hidroxisulphonates, which are inhibitors of several enzymes. During the aerobics oxidation of sulphites and bisulphites there are increase in the concentration of free radicals that cause peroxidation of unsaturated fatty acids, lipid hydroperoxides and disruption of co-oxidation of chlorophylls in chloroplasts, if not quickly eliminated by enzymes of detoxification. The resistance of the plant to the toxic action of SO₂ suggests several mechanisms, among which stand out: the reduction of SO₂ absorption through the stomatal closure, the oxidation of sulphite to sulphate with the subsequent storage of sulphate inside the vacuole and the incorporation in the normal metabolism in organic way, and the scavenging by antioxidant system of peroxidases and superoxide dismutase. If an excess of sulphur is absorbed and the concentration of thiols increase, the sulphur may be accumulated in the form of glutathione, which is a tripeptide with sulphidric bindings, or the excesses of sulphidric groups and sulphites could be converted into sulfides or lost in the form of sulphidric acid, through gas exchange, removing the sulphur from the metabolism of the plant. The objective was to study the mechanisms of immediate protection and recovery of the photosynthetic rate in plants of Centrolobium tomentosum under conditions of stress induced by SO₂, before some kind of leaf injury or phytotoxicity, like chlorosis or leaf necrosis, became visible. For this, an induction chamber has specially been constructed to allow collect of leaf samples in vivo, while the stress was happening. Inside the induction chamber it was put a native species, Centrolobium tomentosum, which had been kept under natural environmental conditions at a greenhouse of the Department of Plant Physiology (UNICAMP). The tests were conducted with SO₂ in the chamber of induction, in a closed system, and this was maintained in a growth chamber, under controlled light, temperature and humidity conditions. Plants of C. tomentosum between eight months and one year old were submited to different concentrations of SO₂ in order to determine the lowest concentration of SO₂ capable to induce, in the photosynthetic rate, the succession of phases that are characteristics of a dynamics of stress. There were used five different plants for each concentration of SO₂ applied, and the photosynthetic rate was recorded using a Portable System for Analysis of gases by Infrared (IRGA). In the same leaves, non-enzymatic antioxidants (photosynthetic pigments and ascorbic acid) and enzymatic antioxidant (superoxide dismutase and glutathione reductase) were analysed. It was determined that the lowest concentration to induce the dynamics of stress in plants of C. tomentosum was 258,07 g SO₂ m­­­ֿ³, which represents a very high concentration regarding the maximum concentrations recommended by governmental organizations to the air pollution control. The succession of phases in the photosynthetic rate was as follows: - Photosynthetic rate before the implementation of SO₂: at this stage, the photosynthetic rate recorded an average of 4.4 μmol CO₂ m­­­ֿ² sֿ¹. Leaf samples were taken, whose analyses correponded to the control. - Phase of alarm: it has begun immediately after the injection of 258,07 g SO₂ m­ֿ³ characterized by the sharp fall in the photosynthetic rate of 92%. Then the stress itself begun, with very low records in photosynthetic rate. - Phase of restitution: in which there was observed the gradual recovery of the photosynthetic rate. - Phase of resistance: in which, after 9 hours of exposure to SO₂, the photosynthetic rate recorded recovery of 50%. After 24 hours of the beginning of the assay, the photosynthetic rate recorded the initial value corresponding to the control, that is, a complete recovery. In all stages, except in the stage of restitution, leaf samples were taken. There were no symptoms of chlorosis or necrosis in the leaves of C. tomentosum after exposure to SO₂ and chemical analysis of photosynthetic pigments corroborate to this observation. However, in stages of stress and complete recovery, the levels of carotenoids increased in relation to the control. The increase of ascorbic acid had the same trend of that of carotenoids in stages of stress and complete recovery. The activity of superoxide dismutase increased significantly in the stage of stress, while the activity of glutathione reductase increased significantly during the complete recovery. The dynamics of stress and the immediate mechanism of detoxification in plants of C. tomentosum submitted to 258,07 g SO₂ m­­­­­ֿ³ suggest that effectively there was actually an oxidative stress, which was overcame in the following way: during the alarm, the sulfite reacted with ribulose bisphosphate before the photo-oxidation to sulphate. This explains the inhibition of carboxylation, with a sharp decrease in the photosynthetic rate. The citotoxic free radicals generated in the chloroplasts, as a result of the photo-oxidation of sulphites, were quickly scavenged by the increase, in the phase of stress, of carotenoids and ascorbic acid and the increasing activity of superoxide dismutase. However, the sulphur from SO₂ has not been immediately accumulated in the form of glutathione. It only occurred when the plant recovered completely the photosynthetic rate. Thus, it was found that C. tomentosum is a resistant species that could be used in areas where SO₂ emissions are high, as in the chemical, petrochemical, steel and fertilizers factories, among others. / Doutorado / Doutor em Biologia Vegetal

American chestnut was once an abundant species that dominated the Eastern U.S. deciduous forests. Although this species is currently functionally extinct due to the chestnut blight, researchers are working on blight-resistant hybrids in hopes of restoring the species. As one potential vector for chestnut reintroduction and dispersal, the reclamation of mine sites are being considered. Recent research has found that reforestation efforts on these reclaimed mine sites provide productive tree growth while also complying with mine-reclamation laws. Understanding how American chestnut performs physiologically on mine sites will aid in the restoration of this species and reclamation of mine sites. The objective of this study was to determine the effect planting treatments have on survival, physiology, and performance of American chestnut. The response of American chestnuts under planting treatments varying in planting method, slow-release fertilizer, a hydrophilic root polymer (Terra-Sorb), and the addition of native forest soil were examined at three sites: a mine site, a quarry, and a greenhouse. Results from this study suggest that fertilizer, hydrophilic root polymers and soil microorganisms produce varying effects on dissimilar sites. Greatest overall survival was found in greenhouse-grown bare-root seedlings. The introduction of fertilizer to the soil substrate lowered emergence and survival of directly-seeded trees at the mine site and quarry, but increased tree growth at all sites and photosynthetic rate at the quarry. However, use of fertilizer resulted in a more negative water potential at the mine site and higher transpiration rate, potentially increasing moisture stress and demand. Increased seed survival, growth, and water status can be accomplished through the use of Terra-Sorb, but only in direct seeded trees on sites with potentially deficient plant-available water. Native forest soil can increase survival in both direct seeded and bare-root planted trees. However, more research is needed on the benefits of native forest soil, as growth and physiological results conflict. It is recommended that site characterization be performed prior to selection of planting treatments. Results of this study can prove beneficial to reclamation specialists with an interest in using mine site reclamation in conjunction with American chestnut restoration.

American chestnut was once an abundant species that dominated the Eastern U.S. deciduous forests. Although this species is currently functionally extinct due to the chestnut blight, researchers are working on blight-resistant hybrids in hopes of restoring the species. As one potential vector for chestnut reintroduction and dispersal, the reclamation of mine sites are being considered. Recent research has found that reforestation efforts on these reclaimed mine sites provide productive tree growth while also complying with mine-reclamation laws. Understanding how American chestnut performs physiologically on mine sites will aid in the restoration of this species and reclamation of mine sites. The objective of this study was to determine the effect planting treatments have on survival, physiology, and performance of American chestnut. The response of American chestnuts under planting treatments varying in planting method, slow-release fertilizer, a hydrophilic root polymer (Terra-Sorb), and the addition of native forest soil were examined at three sites: a mine site, a quarry, and a greenhouse. Results from this study suggest that fertilizer, hydrophilic root polymers and soil microorganisms produce varying effects on dissimilar sites. Greatest overall survival was found in greenhouse-grown bare-root seedlings. The introduction of fertilizer to the soil substrate lowered emergence and survival of directly-seeded trees at the mine site and quarry, but increased tree growth at all sites and photosynthetic rate at the quarry. However, use of fertilizer resulted in a more negative water potential at the mine site and higher transpiration rate, potentially increasing moisture stress and demand. Increased seed survival, growth, and water status can be accomplished through the use of Terra-Sorb, but only in direct seeded trees on sites with potentially deficient plant-available water. Native forest soil can increase survival in both direct seeded and bare-root planted trees. However, more research is needed on the benefits of native forest soil, as growth and physiological results conflict. It is recommended that site characterization be performed prior to selection of planting treatments. Results of this study can prove beneficial to reclamation specialists with an interest in using mine site reclamation in conjunction with American chestnut restoration.

Made available in DSpace on 2014-06-11T19:26:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-10Bitstream added on 2014-06-13T20:47:02Z : No. of bitstreams: 1 graca_jp_me_jabo.pdf: 256015 bytes, checksum: 389bd2988baccfc63d2527a482a1e26f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cana-de-açúcar (Saccharum spp.) é uma das principais culturas das regiões tropicais, cuja produtividade agrícola pode ser afetada pelo déficit hídrico. Para investigar o processo de tolerância e sensibilidade ao déficit hídrico, diferentes parâmetros fisiológicos foram avaliados em cultivares de cana-de-açúcar tolerantes (SP83-2847 e CTC15) e sensível (SP86-155) ao déficit hídrico. A deficiência hídrica afetou todo o aparato fotossintético das plantas de forma diferenciada dentro e entre as cultivares. A taxa fotossintética e condutância estomática diminuíram significativamente para todas as cultivares submetidas ao estresse. Nas plantas controle das cultivares (cv) tolerantes SP83-2847 e CTC15 observou-se que a taxa fotossintética apresentou valores mais altos em comparação a cultivar sensível SP86-155. Resultados do teor relativo de água mostraram que a cultivar CTC15 apresentou melhor condição hídrica durante o período de déficit hídrico. A eficiência quântica do fotossistema II da cultivar SP83-2847 mostrou maior estabilidade nos últimos dias do tratamento experimental, sugerindo que o decréscimo do teor relativo de água estimulou o ajuste da capacidade fotossintética frente às alterações da disponibilidade hídrica. De modo geral, as cultivares SP83-2847 e CTC15, consideradas tolerantes, sob déficit hídrico exibiram melhor desempenho em relação a cultivar sensível SP86-155. Os dados permitem sugerir que tais parâmetros fisiológicos podem ser empregados na avaliação e distinção de genótipos de cana-de-açúcar tolerantes e sensíveis ao déficit hídrico. / The sugarcane (Saccharum spp.) is one of the main crops cultivated in tropical areas, whose agricultural productivity can be affected by drought. To investigate the tolerance and sensitivity process to water deficit, various physiological parameters were evaluated in sugarcane cultivars considered tolerant (SP83-2847 and CTC15) and sensitive (SP86-155) to drought. The water deficit affected the entire photosynthetic apparatus of all plants in different manners, inside and among cultivars. The photosynthetic rate and stomatal conductance decreased significantly for all cultivars, submitted to water stress. In control plants of the tolerant cultivars SP83-2847 and CTC15, it was observed that the photosynthetic rate showed better values in comparison to sensitive cultivar SP86-155. According to relative water content results of the cultivar CTC15 showed better condition water performance during the drought. The quantum efficiency photosystem II of the cultivar SP83-2847 showed greater stability in recent days of the experimental treatment, suggesting that the decline in the relative water content stimulated the adjustment of photosynthetic capacity to face the changes in water availability. Thus, cultivars SP83-2847 and CTC15, considered tolerant under water deficit, showed better performance in comparison to sensitive cultivar SP86-155. The data suggest that these physiological parameters can be used in the evaluation and distinction of drought tolerant and sensitive sugarcane genotypes.