Caracterização morfofuncional e mobilização de reservas primárias durante a germinação e o crescimento inicial de plântulas de Hevea brasiliensis (Willd. Ex Adr de Juss.) Muell. Arg.

Abstract

Considering the advances of the studies with Hevea brasiliensis and the implementation of breeding programs, the propagation of this species has been recommended by the use of grafting. However, complete seed or parts there of (embryos) should not be neglected since, while maintaining the use of clones to improve production, genetics, biochemistry and functional characterization, in addition to the vigor and sanity of the propagated material may contribute to the complete formation of the plants by sexuada (seed germination) and asexual (embryo culture in vitro) for the selection of individuals more balanced in terms of rusticity and production. Thus, the objective of this work was to investigate the implications of the morphology and origin of the H. brasiliensis seeds on germination and seedling formation, from the morphological, histochemical, physiological and biochemical at view. The acquired seeds were categorized as coming from wild and clone matrices and were collected in Altamira-Pa and Belterra-Pa city’s, respectively. The seeds after asepsis were submitted to morphological, physiological and biochemical analyzes, beyond cultivation "in vitro". From the morphophysiological point of view, the seeds of wild and clone H. brasiliensis showed differences in size and color, being wild seeds larger and darker in color. There were no differences in germination morphology. Considering the viability of the seeds, they did not present differences in the moisture contents, and probably due to the high humidity the seeds showed proliferation of fungi, Aspergillus sp. and Penicillium sp., that cause deterioration in seeds. Regarding the germination physiology, the seeds showed a pattern of the three-phase model, but were different in relation to the soaking speed, and the wild seeds absorbed water more slowly than clone, but gain of fresh weight were no different between them. From the biochemical point of view, the constitution of the reserves were similar for both wild and clone seeds. Among the primary metabolites, the lipids correspond to the majority reserves stored in the endosperm of the seeds of the wild H. brasiliensis and clones individuals, being mobilized during germination and initial seedling growth. In the wild and clone seeds the proteins were also mobilized during germination and initial seedling growth and the soluble proteins were mobilized at the beginning of germination and exhibited protein bands in the bands of 7 to 30 kDa that may be associated with the main proteins of synthesis of the latex. Soluble sugar reserves were mobilized more intensely at the beginning of germination and starch at the beginning of seedling initial growth. In wild seeds and clone the nutrient phosphorus (P) and potassium (K) were mobilized at the beginning of germination and initial seedling growth, calcium (Ca) are mobilized at the beginning of germination, nitrogen (N) and magnesium (Mg) are mobilized in the initial growth of the seedlings. For micronutrients, the iron (Fe) was mobilized at the beginning of germination and initial growth of manganese (Mn) is poorly mobilized during germination and zinc (Zn) is mobilized at the beginning of initial seedling growth. The seeds and clone showed behavior and strategies mobilization of the primary metabolites and minerals during the germination and initial seedling growth. Morphological structures of the in vitro, hypocotyl, radicular (primary and secondary root) epicotyl and eophile present different sizes when compared to these same structures of seeds germinated in sand. The cultivation of zygotic embryos presented germination percentages closed to seeds germinated in sand, which may propagation of the species on a large scale. The disinfestation protocols were effective for the low contamination of the embryos. Highest mean of aerial part length was in culture medium with BAP growth and root part, with AIA growth regulator. The higher levels of protein in shoot and root observed in the culture media AIA and MS. The tissues of H. brasiliensis, aerial part and radicular showed protein bands in the bands from 7 to 30 kDa, which may be associated with the main proteins of the latex synthesis. Considering the results obtained in this work it is suggested that it is possible to produce healthy seedlings and perspectives to infer about the beginning of latex synthesis with a focus on future studies of these biomolecules.