Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)

Detalhes bibliográficos
Autor(a) principal: Dias, Paulo Cesar
Data de Publicação: 2006
Tipo de documento: Dissertação
Idioma: por
Título da fonte: LOCUS Repositório Institucional da UFV
Texto Completo: http://locus.ufv.br/handle/123456789/4287
Resumo: This study aimed to identify potential photoprotective mechanisms and how they could be spatially and diurnally adjusted. It was conducted in an arabica coffee tree plantation (northsouth-oriented hedgerows) in Viçosa, Southeastern Brazil. Gas exchange, chlorophyll a fluorescence, and antioxidant system were examined throughout. Evaluations were performed in different canopy positions in August 2005 (dry, cold season with high insolation) when the net photosynthetic rate (A) of coffee tree is very low. This low A largely resulted from nonstomatal limitations. This, associated with an elevated interception of solar radiation, led to a discrete chronic photoinhibition of photosynthesis at noon, particularly in west-faced leaves. In a general way, decreased quantum yield of photosystem II (FPSII) paralleled an increased non-photochemical quenching, indicating a rise in heat dissipation. Apparent electron transport rate also rose during afternoon in west-faced leaves, that was largely a consequence from increased irradiance interception by those leaves, although decreases in both FPSII and photochemical quenching coefficient were observed. As a result, a higher excitation pressure should have occurred in west-faced leaves, thus leading to an increased fraction of irradiance neither used in photochemistry nor dissipated thermally. Regardless of their positions, coffee leaves showed similar ability for energy dissipation into photochemical and nonphotochemical processes. This suggests that the plant might dissipate satisfactorily the excess of absorbed light, i.e. the coffee tree might plastically adjust its photosynthetic machinery to changing irradiance. Steeper leaf angles were related to greater irradiance interception in the upper stratum leaves, particularly in the west side. Chlorophyll and carotenoid concentrations were higher in lower stratum leaves. There was no change in chlorophyll a/b ratio, regardless of the treatments. Activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) generally were similar among different sampled leaves. However, a greater SOD activity was found in upper stratum leaves that could be associated with a larger hydrogen peroxide concentration in those leaves. Little, if any, differences in the activities of SOD, CAT, APX and glutathione peroxidase were observed in paraquat-treated leaves. A stronger decrease in the maximum efficiency of photosystem II was registered in paraquattreated west-faced leaves, similarly to what occurred in the field. Despite west-faced leaves being naturally submitted to a high-light stress, malondialdehyde accumulated in a similar way as in the leaves from other canopy positions. Since the activity of antioxidant enzymes was similar irrespective of leaf position, some other photoprotecting systems should also be of utmost importance for protection of the photosynthetic machinery, particularly in west-faced leaves when exposed to bright irradiance.
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spelling Dias, Paulo Cesarhttp://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4772548J2Damatta, Fábio Murilohttp://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4784185Y9Loureiro, Marcelo Ehlershttp://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4780851Y3Silva, Marco Aurélio Pedron ehttp://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4790898P8Barros, Raimundo Santoshttp://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4787859T6Cruz, Jailson Lopeshttp://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4792357A32015-03-26T13:36:34Z2006-12-012015-03-26T13:36:34Z2006-02-16DIAS, Paulo Cesar. Photosynthesis and photoprotection mechanisms vary spacially in coffee (Coffea arabica L.). 2006. 49 f. Dissertação (Mestrado em Controle da maturação e senescência em órgãos perecíveis; Fisiologia molecular de plantas superiores) - Universidade Federal de Viçosa, Viçosa, 2006.http://locus.ufv.br/handle/123456789/4287This study aimed to identify potential photoprotective mechanisms and how they could be spatially and diurnally adjusted. It was conducted in an arabica coffee tree plantation (northsouth-oriented hedgerows) in Viçosa, Southeastern Brazil. Gas exchange, chlorophyll a fluorescence, and antioxidant system were examined throughout. Evaluations were performed in different canopy positions in August 2005 (dry, cold season with high insolation) when the net photosynthetic rate (A) of coffee tree is very low. This low A largely resulted from nonstomatal limitations. This, associated with an elevated interception of solar radiation, led to a discrete chronic photoinhibition of photosynthesis at noon, particularly in west-faced leaves. In a general way, decreased quantum yield of photosystem II (FPSII) paralleled an increased non-photochemical quenching, indicating a rise in heat dissipation. Apparent electron transport rate also rose during afternoon in west-faced leaves, that was largely a consequence from increased irradiance interception by those leaves, although decreases in both FPSII and photochemical quenching coefficient were observed. As a result, a higher excitation pressure should have occurred in west-faced leaves, thus leading to an increased fraction of irradiance neither used in photochemistry nor dissipated thermally. Regardless of their positions, coffee leaves showed similar ability for energy dissipation into photochemical and nonphotochemical processes. This suggests that the plant might dissipate satisfactorily the excess of absorbed light, i.e. the coffee tree might plastically adjust its photosynthetic machinery to changing irradiance. Steeper leaf angles were related to greater irradiance interception in the upper stratum leaves, particularly in the west side. Chlorophyll and carotenoid concentrations were higher in lower stratum leaves. There was no change in chlorophyll a/b ratio, regardless of the treatments. Activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) generally were similar among different sampled leaves. However, a greater SOD activity was found in upper stratum leaves that could be associated with a larger hydrogen peroxide concentration in those leaves. Little, if any, differences in the activities of SOD, CAT, APX and glutathione peroxidase were observed in paraquat-treated leaves. A stronger decrease in the maximum efficiency of photosystem II was registered in paraquattreated west-faced leaves, similarly to what occurred in the field. Despite west-faced leaves being naturally submitted to a high-light stress, malondialdehyde accumulated in a similar way as in the leaves from other canopy positions. Since the activity of antioxidant enzymes was similar irrespective of leaf position, some other photoprotecting systems should also be of utmost importance for protection of the photosynthetic machinery, particularly in west-faced leaves when exposed to bright irradiance.O comportamento das trocas gasosas, dos parâmetros de fluorescência da clorofila a e do sistema antioxidativo foi estudado em plantas adultas de café arábica cultivadas em campo e orientadas no sentido norte-sul, em Viçosa-MG, objetivando-se identificar potenciais mecanismos de fotoproteção e avaliar como tais mecanismos se ajustariam espacial e diurnamente. Para isso, procederam-se às avaliações em diferentes posições da copa, em agosto de 2005, época relativamente fria, seca e com alta insolação, na qual o cafeeiro exibe taxas muito baixas de fotossíntese. As baixas taxas fotossintéticas foram largamente resultantes de limitações não-estomáticas. Isso, aliado à elevada interceptação da radiação solar, particularmente pelas folhas da face oeste à tarde, traduziu-se numa discreta fotoinibição crônica da fotossíntese. De modo geral, menores valores do rendimento quântico fotoquímico do fotossistema II (FFSII) foram acompanhados por incrementos paralelos no coeficiente de extinção não-fotoquímica, indicando aumento na capacidade de dissipação de calor. Ademais, a taxa de transporte aparente de elétrons aumentou, à tarde, nas folhas da face oeste, fato largamente associado à elevada irradiância interceptada por aquelas folhas, a despeito dos decréscimos observados em FFSII e no coeficiente de extinção fotoquímica. Como conseqüência, uma maior pressão de excitação ocorreu nas folhas da face oeste, resultando no aumento da proporção de energia não utilizada na fase fotoquímica e nem dissipada termicamente. De modo geral, as folhas do cafeeiro, independentemente de faces ou estratos, apresentaram capacidade similar de dissipação da radiação fotossinteticamente ativa em processos fotoquímicos e não-fotoquímicos. Isso sugere que o cafeeiro pode dissipar, de forma aparentemente satisfatória, o excesso da energia absorvida, apresentando capacidade de resposta plástica de sua maquinaria fotossintética às variações da irradiância. Maiores ângulos foliares mostraram-se relacionados à maior interceptação de luz pelas folhas dos estratos superiores, principalmente na face oeste da copa. A concentração de clorofilas e carotenóides foi maior em folhas dos estratos inferiores, mas não houve nenhuma alteração na razão clorofila a/clorofila b. As atividades da dismutase do superóxido (SOD), da catalase (CAT) e da peroxidase do ascorbato (APX), foram, de modo geral, semelhantes nas folhas, independentemente de estratos e faces. Somente uma maior atividade de SOD em folhas dos estratos superiores foi observada, fato que pode estar associado a maior acúmulo de peróxido de hidrogênio nas folhas daqueles estratos, independentemente de faces. Poucas foram as diferenças nas atividades da SOD, da CAT, da APX e da peroxidase da glutationa entre folhas das diferentes faces e estratos, quando se induziu o estresse oxidativo com Paraquat, mas uma maior redução da eficiência fotoquímica nas folhas dos estratos da face oeste foi observada, à semelhança do que ocorreu em condições de campo. Apesar de as folhas localizadas na face oeste da copa estarem submetidas a um maior estresse luminoso e, portanto, sujeitas de forma mais marcante ao estresse oxidativo, não houve danos celulares consideráveis, estimados pelo acúmulo de aldeído malônico. Uma vez que a atividade das enzimas estudadas foi muito similar, independentemente da posição na copa, sugere-se que outros sistemas de fotoproteção possam ter maior importância na proteção da maquinaria fotossintética, particularmente nas folhas da face oeste quando expostas à elevada irradiância.Coordenação de Aperfeiçoamento de Pessoal de Nível Superiorapplication/pdfporUniversidade Federal de ViçosaMestrado em Fisiologia VegetalUFVBRControle da maturação e senescência em órgãos perecíveis; Fisiologia molecular de plantas superioresCaféAdaptações morfológicasAdaptações fisiológicasTolerância à secaFotossínteseCoffea arabicaCoffeeMorphological adaptationsPhysiological adaptatationsDrought tolerancePhotosynthesisCoffea arabicaCNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETALVariação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)Photosynthesis and photoprotection mechanisms vary spacially in coffee (Coffea arabica L.)info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisinfo:eu-repo/semantics/openAccessreponame:LOCUS Repositório Institucional da UFVinstname:Universidade Federal de Viçosa (UFV)instacron:UFVORIGINALtexto completo.pdfapplication/pdf218982https://locus.ufv.br//bitstream/123456789/4287/1/texto%20completo.pdf38c14fe52f8aa57350cdc239a6dbf920MD51TEXTtexto completo.pdf.txttexto completo.pdf.txtExtracted texttext/plain93918https://locus.ufv.br//bitstream/123456789/4287/2/texto%20completo.pdf.txt6701c1b61ca1662aab56e5eb8ff9e521MD52THUMBNAILtexto completo.pdf.jpgtexto completo.pdf.jpgIM Thumbnailimage/jpeg3758https://locus.ufv.br//bitstream/123456789/4287/3/texto%20completo.pdf.jpg493d2b12be88f20d45afa6412a1370dbMD53123456789/42872016-04-10 23:07:09.488oai:locus.ufv.br:123456789/4287Repositório InstitucionalPUBhttps://www.locus.ufv.br/oai/requestfabiojreis@ufv.bropendoar:21452016-04-11T02:07:09LOCUS Repositório Institucional da UFV - Universidade Federal de Viçosa (UFV)false
dc.title.por.fl_str_mv Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)
dc.title.alternative.eng.fl_str_mv Photosynthesis and photoprotection mechanisms vary spacially in coffee (Coffea arabica L.)
title Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)
spellingShingle Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)
Dias, Paulo Cesar
Café
Adaptações morfológicas
Adaptações fisiológicas
Tolerância à seca
Fotossíntese
Coffea arabica
Coffee
Morphological adaptations
Physiological adaptatations
Drought tolerance
Photosynthesis
Coffea arabica
CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETAL
title_short Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)
title_full Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)
title_fullStr Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)
title_full_unstemmed Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)
title_sort Variação espacial da fotossíntese e de mecanismos de fotoproteção no cafeeiro (Coffea arabica L.)
author Dias, Paulo Cesar
author_facet Dias, Paulo Cesar
author_role author
dc.contributor.authorLattes.por.fl_str_mv http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4772548J2
dc.contributor.author.fl_str_mv Dias, Paulo Cesar
dc.contributor.advisor1.fl_str_mv Damatta, Fábio Murilo
dc.contributor.advisor1Lattes.fl_str_mv http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4784185Y9
dc.contributor.referee1.fl_str_mv Loureiro, Marcelo Ehlers
dc.contributor.referee1Lattes.fl_str_mv http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4780851Y3
dc.contributor.referee2.fl_str_mv Silva, Marco Aurélio Pedron e
dc.contributor.referee2Lattes.fl_str_mv http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4790898P8
dc.contributor.referee3.fl_str_mv Barros, Raimundo Santos
dc.contributor.referee3Lattes.fl_str_mv http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4787859T6
dc.contributor.referee4.fl_str_mv Cruz, Jailson Lopes
dc.contributor.referee4Lattes.fl_str_mv http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4792357A3
contributor_str_mv Damatta, Fábio Murilo
Loureiro, Marcelo Ehlers
Silva, Marco Aurélio Pedron e
Barros, Raimundo Santos
Cruz, Jailson Lopes
dc.subject.por.fl_str_mv Café
Adaptações morfológicas
Adaptações fisiológicas
Tolerância à seca
Fotossíntese
Coffea arabica
topic Café
Adaptações morfológicas
Adaptações fisiológicas
Tolerância à seca
Fotossíntese
Coffea arabica
Coffee
Morphological adaptations
Physiological adaptatations
Drought tolerance
Photosynthesis
Coffea arabica
CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETAL
dc.subject.eng.fl_str_mv Coffee
Morphological adaptations
Physiological adaptatations
Drought tolerance
Photosynthesis
Coffea arabica
dc.subject.cnpq.fl_str_mv CNPQ::CIENCIAS BIOLOGICAS::BOTANICA::FISIOLOGIA VEGETAL
description This study aimed to identify potential photoprotective mechanisms and how they could be spatially and diurnally adjusted. It was conducted in an arabica coffee tree plantation (northsouth-oriented hedgerows) in Viçosa, Southeastern Brazil. Gas exchange, chlorophyll a fluorescence, and antioxidant system were examined throughout. Evaluations were performed in different canopy positions in August 2005 (dry, cold season with high insolation) when the net photosynthetic rate (A) of coffee tree is very low. This low A largely resulted from nonstomatal limitations. This, associated with an elevated interception of solar radiation, led to a discrete chronic photoinhibition of photosynthesis at noon, particularly in west-faced leaves. In a general way, decreased quantum yield of photosystem II (FPSII) paralleled an increased non-photochemical quenching, indicating a rise in heat dissipation. Apparent electron transport rate also rose during afternoon in west-faced leaves, that was largely a consequence from increased irradiance interception by those leaves, although decreases in both FPSII and photochemical quenching coefficient were observed. As a result, a higher excitation pressure should have occurred in west-faced leaves, thus leading to an increased fraction of irradiance neither used in photochemistry nor dissipated thermally. Regardless of their positions, coffee leaves showed similar ability for energy dissipation into photochemical and nonphotochemical processes. This suggests that the plant might dissipate satisfactorily the excess of absorbed light, i.e. the coffee tree might plastically adjust its photosynthetic machinery to changing irradiance. Steeper leaf angles were related to greater irradiance interception in the upper stratum leaves, particularly in the west side. Chlorophyll and carotenoid concentrations were higher in lower stratum leaves. There was no change in chlorophyll a/b ratio, regardless of the treatments. Activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) generally were similar among different sampled leaves. However, a greater SOD activity was found in upper stratum leaves that could be associated with a larger hydrogen peroxide concentration in those leaves. Little, if any, differences in the activities of SOD, CAT, APX and glutathione peroxidase were observed in paraquat-treated leaves. A stronger decrease in the maximum efficiency of photosystem II was registered in paraquattreated west-faced leaves, similarly to what occurred in the field. Despite west-faced leaves being naturally submitted to a high-light stress, malondialdehyde accumulated in a similar way as in the leaves from other canopy positions. Since the activity of antioxidant enzymes was similar irrespective of leaf position, some other photoprotecting systems should also be of utmost importance for protection of the photosynthetic machinery, particularly in west-faced leaves when exposed to bright irradiance.
publishDate 2006
dc.date.available.fl_str_mv 2006-12-01
2015-03-26T13:36:34Z
dc.date.issued.fl_str_mv 2006-02-16
dc.date.accessioned.fl_str_mv 2015-03-26T13:36:34Z
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dc.identifier.citation.fl_str_mv DIAS, Paulo Cesar. Photosynthesis and photoprotection mechanisms vary spacially in coffee (Coffea arabica L.). 2006. 49 f. Dissertação (Mestrado em Controle da maturação e senescência em órgãos perecíveis; Fisiologia molecular de plantas superiores) - Universidade Federal de Viçosa, Viçosa, 2006.
dc.identifier.uri.fl_str_mv http://locus.ufv.br/handle/123456789/4287
identifier_str_mv DIAS, Paulo Cesar. Photosynthesis and photoprotection mechanisms vary spacially in coffee (Coffea arabica L.). 2006. 49 f. Dissertação (Mestrado em Controle da maturação e senescência em órgãos perecíveis; Fisiologia molecular de plantas superiores) - Universidade Federal de Viçosa, Viçosa, 2006.
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