Germination of Ocotea pulchella em laboratorio e em ambiente natural de Restinga

• Published in: Brazilian journal of biology 2009-08, Vol.69 (3), p.935
• Main Authors: Pires, L.A, Cardoso, V.J.M, Joly, C.A, Rodrigues, R.R
• Format: Article
• Language: English
• Subjects: Germination; Seeds; Soil moisture; Soils
• ISSN: 1519-6984; 1678-4375

The germination response of Ocotea pulchella (Nees) Mez seeds to light, temperature, water level and pulp presence is introduced. The laboratory assays were carried out in germination chambers and thermal-gradient apparatus, whereas the field assays were performed in environments with distinct light, temperature and soil moisture conditions within a permanent parcel of Restinga forest of the Parque Estadual da Ilha do Cardoso, Cananeia, Sao Paulo. The seeds do not exhibit dormancy, they are non photoblastic, and a loss of viability in dry stored seeds can be related to a decrease in water content of the seed. The presence of the pulp and the flooded substratum influenced negatively the germination of O. pulchella seeds tested in the laboratory. Otherwise, light and temperature probably are not limiting factors of the germination of O. pulchella seeds in the natural environment of Restinga. The optimum temperature range for germination of Ocotea pulchella seeds was 20 to 32 °C, the minimum or base temperature estimated was 11 °C and the maximum ranged between 33 and 42 °C. The isotherms exhibited a sigmoidal pattern well described by the Weibull model in the sub-optimal temperature range. The germinability of O. pulchella seeds in the understorey, both in wet and dry soil, was higher than in gaps. Germination was not affected by fluctuations in soil moisture content in the understorey environment, whereas in gaps, germination was higher in wet soils. Thus, the germination of this species involves the interaction of two or more factors and it cannot be explained by a single factor.