Respostas fisiológicas a dessecação e a re-hidratação em quatro espécies de pteridófitas epifíticas


IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia




Epiphytic plants are more sensible to environmental variations than terrestrial plants, especially in relation to water availability. The water then stands out as one of the most important limiting factors. However, some species have evolved the ability to tolerate desiccation, showing a significant adaptive advantage in the occupation of habitats. The aim of this study was to determine the degree and mechanisms of drought tolerance of four species of epiphytic ferns that commonly co-occur on the same host tree. Expanded and hydrated fronds were collected for quantification and comparison the relative water content, membrane integrity, photosynthetic pigments, flavonoids, phenols, soluble sugars and chlorophyll fluorescence over the processes of desiccation and rehydration. The results of the present study allowed us to infer that the tolerant species have more physiological adaptations during periods of desiccation and rehydration. Thus, tolerant species showed distinct degrees of tolerance: Polypodium polypodioides var. minimum was the most tolerant, followed by Pleopletis pleopeltifolia and Polypodium hirsutissimum. While Microgramma squamulosa shown avoidance desiccation. We conclude that these species exhibit different ecophysiological strategies in relation to water stress, minimizing possible irreversible damage to cell membranes. Thus optimize capture of light during periods of rehydration, reduce inter-specific competition and facilitating the co-occurrence of these four species.


membrane integrity total flavonoids dessecação desiccation tolerance flavonoides total phenols fenois total soluble sugars clorofila chlorophyll fluorescecnce fluorescencia hidratação polypodiaceae polyporaceae

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