Germination of Ocotea pulchella (Nees) Mez (Lauraceae) seeds in laboratory and natural restinga environment conditions

Abstract

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, Cananéia, São 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. Keywords

Effect of flooding on survival and initial growth of Ocotea pulchella (Nees) Mez. seedlings in semi-controlled light conditions

“…In general, the survival of O. pulchella seedlings was not aff ected by fl ooding. Th ose results are in agreement with the response of O. pulchella seeds sowed both in wet and dry soil, whose germinability in the understory of Restinga forest was higher than in gaps (Pires et al 2009), suggesting that the species can be both fl ood and shade-tolerant at least in the early developmental stages. Nine-month-old O. pulchella plants, here referred to as "juveniles", were in turn relatively susceptible to fl ooding whether or not they were shaded.…”

Effect of reduced water potential on seed germination of a forest tree: a hydrotime approach

“…Some studies evaluated the role of Ψ on seed germination of Brazilian species (Botelho and Perez, 2001;Fonseca and Perez, 2003;Rego et al, 2007), but rarely explaining whether germination would fit the presupposes of hydrotime models (Cardoso and Pereira, 2008;Oliveira et al, 2019). Most attention regards to the role of temperature, rather than water potential, as described by thermal time models in neotropical species (Cardoso and Pereira, 2009;Pires et al, 2009;Daibes and Cardoso, 2018;Duarte et al, 2018).…”

Sobrevivência e crescimento inicial de Ocotea pulchella (Lauraceae) em uma floresta de restinga da Ilha do Cardoso, SP

“…Esta característica deve ter sido determinante na classificação de O. pulchella como espécie do estágio inicial de sucessão (Salimon & Negrelle2001;Carrasco 2003). Por outro lado, O. pulchella apresenta algumas características opostas ao descrito para tais espécies, como crescimento relativamente lento e pouco investimento em biomassa foliar, aqui reportados, bem como sementes sem dormência capazes de germinar na sombra (Pires et al 2009).…”