Caracterização morfofisiológica e bioquímica de três morfotipos de Paubrasilia echinata Lam. em resposta à luz

• Autor(a) principal: Gama, Vinícius Novo
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/10033
• topic: Plant biochemistry; Luminosity; Plant morphophysiology; Brazil wood; Ultraviolet-B; Bioquímica vegetal; Luminosidade; Ultravioleta-B; Agronomia; Química vegetal; Plantas - Efeito da luz; Morfologia vegetal; Fisiologia vegetal; Pau-brasil; Radiação ultravioleta; 57

The contradictory reports about the functional Responses of brazilwood (Paubrasilia echinata Lam.) in different light conditions, may be relation with genetic variations, which reflect on morphophysiological divergences among populations of this species. This fact makes it difficult to choose the variants of this species to propagation and maintenance of seedlings, as well as its ex situ reintroduction to the Brazilian Atlantic Forest. With the purpose of provide precise information about the conservation and promotion of the most appropriate forest management with P. echinata, the study sought to characterize the morphophysiological and biochemical responses of three brazilwood morphotypes: small variant (SV), medium variant (MV) and large variant (LV) in relation to light. In a first work, growth, gas exchange, phenolic compound content, antioxidant enzyme activity (CAT, APX, POD and PPO) and total auxin concentration of the three morphotypes were performed under 100% and 15% light. It was observed that secondary metabolism, antioxidative process, photosynthesis and growth parameters indicate LV and MV as morphological variations with tendencies for heliophilous plants. Differently from SV, which presented umbrophilous tendencies. These different responses of brazilwood morphotypes under high incidence of light, instigated the development of a second work, Which sought to evaluate the effects of supplementation of UV-B incident radiation on a heliophilous morphotype, MV, and umbrophilous, SV. For this, measurements of growth, photosynthesis, contents of UV absorption compounds, structural and non-structural carbohydrates, as well as quantification of hydrogen peroxide (H2O2) and malonaldehyde (MDA) contents were performed. The effect of UV-B was positive in MV, as it improved its photochemical efficiency and optimized its gas exchange and growth. The incidence of UV-B Provided acclimative responses in MV that presented with a high degree of tolerance to this radiation. This fact can be explained by the heliophilic behavior of this morphotype, with tolerance to environments with high UV irradiance prevalence. On the other hand, the incidence of radiation stimulated photoinhibitory effects in SV, which 11 presented lower growth, lower photosynthetic rate and high respiration. The increase of the hydrogen peroxide contents stimulated oxidative damages in SV visibly translated as foliar chlorotic areas that evolved to foliar necrosis and abscision. Based on floristics works reports already published about the natural incidence of the P. echinata morphotypes, it is observed that SV can be found in dense umbrophilous forests or high-shaded forest; while MV and LV can be found in regions with more open forest, with more clearings and greater irradiance. It is concluded that the differences between the three morphotypes of brazilwood in reference to the contrasting ligth and the exposure of ultraviolet-B (UV-B) radiation presented in this study seem to reflect the prevailing conditions of their centers of origin. Thus, it is suggested the use of SV, with umbrophilous characteristics, for the recovery of the Atlantic forest dense areas, with prevalence in wet and coastal regions. In contrast, it is recommended the plantation of MV and LV in the Atlantic forest deciduous and semideciduous seasonal areas, with prevalence of clearings and high irradiances