Fisiologia da germinação de sementes e morfoanatomia do foliólulo de espécies de Stryphnodendron Mart

Abstract

The objective of this study was to evaluate the variation of biometrical features of seeds, the effect of pre-germinative treatments to overcome dormancy, the influence of the temperature and light, and the priming in the germination of seeds of Stryphnodendron adstringens (Mart.) Coville, Stryphnodendron obovatum Benth. and Stryphnodendron polyphyllum Mart., and to describe and to compare the blade morphoanatomy of Stryphnodendron species. The seeds used were collected in Chapadão do Sul - MS. In the first chapter it were described the variation of biometrical features existing among the seeds of Stryphnodendron species and the effectiveness of the following pre-germinative treatments to overcoming the dormancy: 1) Immersion in GA3 200 mg.L-1 (GA200) during 24 h; 2) Immersion in water during 24 h; 3) Immersion in sulfuric acid PA (H2SO4) during 20' (minutes); 4) Immersion in H2SO4 PA during 20' + GA200 during 24 h; 5) Immersion in H2SO4 PA during 20' + water during 24 h; 6) Immersion in H2SO4 PA during 40'; 7) Immersion in H2SO4 PA during 40' + GA200 during 24 h; 8) Immersion in H2SO4 PA during 40' + water during 24 h; 9) Immersion in water at 100°C during 5'; 10) Immersion in water at 100°C during 5' + GA200 during 24 h; 11) Immersion in water at 100°C during 5' + water during 24 h; and the control. For each species, the experiment was carried out in a completely randomized experimental design with four repetitions of 20 seeds. The biometrical data had evidenced the biggest size of the seeds of S. polyphyllum in relation to S. adstringens and S. obovatum ones, that had present great similarity. For the three species, the sulfuric acid scarification per 40', followed or not by embebition in GA200 or water for 24 hours did not increase the percentage and speed of seedlings emergency. In the second chapter the influence of the temperature and light in the germination of the seeds of the Stryphnodendron species was described. The experiment was carried out in a completely randomized experimental design in factorial scheme of 3 (temperatures) x 4 (qualities of light) with four repetitions of 20 seeds. The results shown that the seeds of the three species of Stryphnodendron Mart. studied presented a neutral photoblastic behavior. The three studied temperatures are inside of the excellent band for the germination of the seeds of S. adstringens and S. polyphyllum, whereas for S. obovatum the best temperature is 25°C. In the third chapter the effect of the priming in the germination of Stryphnodendron seeds was described. The seeds were conditioned in the following treatments: 1) PEG 6000 (- 1.0 MPa); 2) PEG 6000 (- 1.0 MPa) + KNO3 (- 1.0 MPa); 3) KNO3 (- 1.0 MPa); 4) Water and 5) Control, and placed in a germination chamber (BOD type) regulated in the temperature of 20°C (± 2°C) during 0 h (control), 6 h, 12h and 24 hours, under continuous light. For each species, the experiment was carried out in a completely randomized experimental design in factorial scheme of 5 (pre-conditioning treatments) x 4 (incubation times) with four repetitions of 20 seeds. In the conditions that the experiment was carried out, the treatments of priming tested did not change the physiological performance of the Stryphnodendron seeds. Stryphnodendron species are commonly used in Brazilian popular medicine. Its farmacological properties are related to the high concentrations of condensed tannins in the bark of these plants. However, Stryphnodendron species share many external characters, what makes correct identification of species difficult. Thus, in the fourth chapter it was described the blade morphoanatomy of the three species of Stryphnodendron, using the medium region of terminal leaflet and, proceeding as the usual methods for anatomic study. Some observed parameters are of great value for the identification of medicinal drugs, among them, the great ones observed were: 1) leaflet size - it was bigger in S. adstringens, S. polyphyllum and S. obovatum, respectively; 2) the thickness of central nervure – it was thicker in S. adstringens (134,7 µm), S. obovatum (112,8 µm) and S. polyphyllum (29,7 µm) respectively; 3) sinuosity of epidermal cells – S. adstringens presents wall of epidermal cells more sinuous than S. obovatum, whereas S. polyphyllum presents straight wall of the epidermal cells.