Name: VINÍCIUS NOVO GAMA
Type: PhD thesis
Publication date: 03/03/2017
Advisor:
Name |
Role |
|---|---|
| Geraldo Rogério Faustini Cuzzuol | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Fábio Murilo DaMatta | Internal Examiner * |
| Geraldo Rogério Faustini Cuzzuol | Advisor * |
| José Eduardo Macedo Pezzopane | External Examiner * |
| JOSÉ FRANCISCO DE CARVALHO GONÇALVES | External Alternate * |
| Luis Fernando Tavares de Menezes | Internal Examiner * |
| Marcelo Schramm Mielke | External Examiner * |
| Viviana Borges Corte | Internal Alternate * |
Summary: The contradictory reports about the functional adaptations under irradiance of brazilwood (Paubrasilia echinata Lam.) may be related to the morphological divergence reflected by genetic variations among this species populations. This fact makes it difficult to classify with accuracy this vegetable in reference 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 objective of this work was to characterize the morphophysiological and biochemical responses of three brazilwood morphotypes: small variant (SV), medium variant (MV) and large variant (LV) in relation to irradiance. 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% irradiance. 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. This adaptive divergence under high irradiance between brazilwood morphotypes instigated the development of a second work, seeking 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 caused adaptive effects 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
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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 irradiance 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.
Keywords: Plant biochemistry luminosity plant morphophysiology brazilwood ultraviolet-B
