Ecofisiologia do estresse luminoso em espécies de Cattleya Lindl

• Ano de defesa: 2012
• Autor(a) principal: Pinheiro, Clodoaldo Leites
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Biodiversidade Tropical; UFES; Programa de Pós-Graduação em Biodiversidade Tropical
• Palavras-chave em Português: Orchid; Plants - light stress; Fluorescence; Orquídea; Plantas x Efeito da luz; Fluorescência; Ecologia; 502
• Link de acesso: http://repositorio.ufes.br/handle/10/5208

Cattleya Lindl. (Orchidaceae) are epiphytic active on the dynamic neotropical biodiversity regulation and on keeping the remnant forest low entropy. The fragmented habitat exposures this species to conditions of over light or transient light pulse. The plants auto adjust to the light heterogeneous system adjusting their structures and physiological state in an attempt to reach their ultimate functional state. Therefore, the photosynthetic apparatus composition is highly sensitive on the quality and amount of luminous spectrum energy. Thereby, the chlorophyll a fluorescence emission can be used as an efficient mechanism to measure the photosynthetic efficiency, especially on physiologically stressful environments. On this same line, Cattleya ecological and biophysical aspects become relevant in terms of ecophysiological studies. The present survey aimed to respond: Why biogeographic patterns of Cattleya species seem to reflect the efficient mechanisms of resistance to photochemical photoinhibition face to an habitat light environment heterogeneity? Hence, the following hypothesis were tested: (1) species with more features derived have a higher resistance to light stress, and (2) structural and functional changes of photosynthetic units can retreating management and conservation strategies of Cattleya Lindl. species. Cattleya amethystoglossa Linden & Rchb.f., C. guttata Lindl., C. granulosa Lindl. and C. walkeriana Gardner plants had a full sun exposure and chlorophyll a fluorescence transient (Handy-PEA, Hansatech) was made on previously dark adapted leaves (30’), at 5 am (controle), 8am, 10am, 12pm, 2pm, 4pm, 6pm, 8pm and e 5am* of the next day (recovery). The registered light intensity was of 0, 1386, 1892, 2350, 1899, 1301, 347, 0 and 0 µmol photons m-2 s -1, respectively (QSPAR, Hansatech). C. warneri T. Moore, C. shofieldiana Rchb.f., and C. harrisoniana Batem. ex Lindl. were exposure to full sun for 5, 35 and 120’ at 12am (2259 µmol m-2 s -1). After being transferred to a shaded place, measures were made at 1am, 3pm, 5pm, 7pm and 9am (recovering) of the next day (701, 270, 30, 0 and 154 µmol m-2s -1 , respectively). The transient O-L-K-J-I-P analysis and of the JIP test parameters indicated that evidences about photochemical photoinhibition split plants of C. amethystoglossa and C. granulosa (dynamic photoinhibition) from plants of C. gutatta and C. walkeriana (chronic photoinhibition). The physiological plasticity importance was proved in respond to sun flecks on C. schofieldiana plants. Primitive plants have less resistance and physiological plasticity to light stress, which have more distribution representative in the Atlantic forest central biodiversity corridor, the corridor of the Serra do Mar and riparian vegetation of the Cerrado biome. However, plants with more features derived were related with the Northeast Corridor of the Atlantic forest. C. amethystoglossa seems to express processes of speciation and vicariance.The JIP test biophysical expressions suggest active reaction silent centers as efficient photochemical energy dissipation. In this context, disturbs on photosynthetic apparatus modulation of different photosynthetic photon flows were followed by functional and structural adjusts of the photosynthetic units. Accordingly, the use of chlorophyll a fluorescence analysis is able to become efficient when it comes to evaluate ecophisiological responses of Orchidaceae species under high light and sun flecks influence, retreating management and conservation strategies.