A dificuldade técnica devida à ocorrência de dormência das sementes é um entrave para a produção de mudas de espécies nativas em programas de recomposição de áreas degradadas do Cerrado. Objetivou-se com este trabalho avaliar o efeito do condicionamento fisiológico e do sombreamento na qualidade de sementes de duas espécies de barbatimão (Stryphnodendron polyphyllum e S. adstringens). Foram utilizados os seguintes tratamentos pré-germinativos: 1) PEG -1,0 MPa; 2) PEG -1,0 MPa+ KNO3 -1,0 MPa; 3) PEG -0,5 MPa; 4) PEG -0,5 MPa + KNO3 -0,5 MPa; 5) KNO3 -1,0 MPa; 6) Água deionizada; e 7) sementes que não receberam nenhum tratamento pré-germinativo (testemunha). Durante os tratamentos pré-germinativos, as sementes permaneceram incubadas em B.O.D. regulada na alternância de 20/30 ºC, durante 24 h, e em seguida semeadas em bandejas de células com Plantmax® mantidas em quatro níveis de sombreamento (pleno sol, 30%, 50% e 70%) com quatro repetições de 20 sementes. O condicionamento fisiológico com água de sementes de S. polyphyllum e S. adstringens e posterior semeadura em ambiente sombreado de 50 a 70% são eficientes para obter emergência rápida e elevada, maior altura e massa seca das plântulas. As sementes de S. polyphyllum podem ser osmocondicionadas com PEG 1,0 e PEG -0,5 MPA se a semeadura for realizada sob 30% de sombra. Entretanto, a semeadura de S. polyphyllum e S. adstringens não deve ser realizada a pleno sol.

The technical difficulty to obtain seedlings due to seed dormancy is an obstacle in the production of native species in the recovery of Brazilian Savannah degraded areas programs. Thus, the objective of the present study was to evaluate the effect of physiological conditioning and shading on seed quality of two species of barbatimão (Stryphnodendron polyphyllum and Strypnhodendron adstringens). Seeds were soaked in seven conditions: 1) PEG -1.0 MPA; 2) PEG -1.0 MPA+ KNO3 -1.0 MPA; 3) PEG -0.5 MPA; 4) PEG -0.5 MPA + KNO3 -0.5 MPA; 5) KNO3 -1.0 MPA; 6) distillate water and 7) without soaking (control). During the treatments, the seeds remained incubated in BOD 20/30 ºC for 24 h, then they were sown in cell trays containing Plantmax®, and maintained under four shading levels (full sun, 30%, 50% and 70%) with four repetitions of 20 seeds. After the evaluation of the emergency percentage, the seedlings were transplanted and kept under the same shade levels. The physiological conditioning on water of both species seeds, followed by sowing under 50 to 70% shade, are effective for faster and high emergency, greater height and dry mass of seedlings. S. polyphyllum seeds can be conditioned with PEG -1.0 MPa and PEG - 0.5 MPa if sown under 30% shade. However, seeds from S. polyphyllum and S. adstringens species should not be sown at full sun.

Poly(3-hydroxybutyrate) (PHB) based on nanocomposites containing different amounts of a commercial organically modified clay (viscogel B7) were prepared employing solution intercalation method. Three solvents, such as: CHCl3, dimethylchloride (DMC) and tetrahydrofuran (THF) were used. The relationship among the processing conditions; molecular structure and intermolecular interaction, between both nanocomposite components, were investigated using a nuclear magnetic resonance (NMR), as a part of characterization methodology, which has been used by Tavares et al. It involves the hydrogen spin-lattice relaxation time, T1H, by solid state nuclear magnetic resonance, employing low field NMR. X ray diffraction was also employed because it is a conventional technique, generally used to obtain the first information on nanocomposite formation. Changes in PHB crystallinity were observed after the organophilic nanoclay had been incorporated in the polymer matrix. These changes, in the microstructure, were detected by the variation of hydrogen nuclear relaxation time values and by X ray, which showed an increase in the clay interlamelar space due to the intercalation of the polymer in the clay between lamellae. It was also observed, for both techniques, that the solvents affect directly the organization of the crystalline region, promoting a better intercalation, considering that they behave like a plasticizer.