Seed dormancy and germination behaviour of tropical rainforest tree species from Sri Lanka

Abstract

Plant community-level studies on seed dormancy traits are important to understand and determine the significance of seed dormancy in different ecosystems. Hence, we studied seed dormancy and other related seed biological traits of 42 selected tropical lowland rainforest tree species from Sri Lanka, aiming to address seed dormancy class(es) for a biodiverse tropical lowland wet zone forest community and the relationship between dormancy classes, forest strata and seed dispersal mechanisms. Seed germination, imbibition, embryo length:seed length ratio, embryo morphology and the effect of gibberrelic acid on seed germination were determined. Sixty-two percent of the species with T50 < 30 days were identified as having fast-germinating seeds and the remaining 38% with T50 > 30 possessed slow-germinating seeds. Seeds of 33 species had fully developed embryos, while nine species had underdeveloped embryos; three had morphological dormancy (MD) and six morphophysiological dormancy (MPD). Treatment with gibberellic acid revealed physiological dormancy (PD) in seeds of six species, and the response to manual scarification confirmed physical dormancy (PY) in seeds of Pericopsis moonina. The majority of tropical lowland rainforests had non-dormant (ND) species (62%), and 14.3, 14.3, 7 and 2.3% of the species had MPD, PD, MD, and PY, respectively. Non-dormancy decreased for taxa from the upper strata to the lower strata of the forest. ND seeds were dispersed during the rainy season. Thus, non-dormancy seems to be the most dominant germination behaviour among the tree species in the lowland rainforest of Sri Lanka with the class of dormancy related to forest strata and dispersal time.

Diversity of seed storage behavior of tree species from tropical lowland rainforests in Sri Lanka, a global biodiversity hotspot

“…The remaining seeds were cut open at the end of the experiment and the embryo was observed to determine the viability (white firm viable embryo vs. soft‐gray non‐viable embryos). Dormancy‐breaking treatments such as GA 3 treatment and manual scarification were employed for dormant seeds as identified by Samarasinghe et al (2022). Dormancy‐breaking treatments were applied after storage treatment prior to the germination test.…”

“…Thus, restoring these forests is vital to safeguard the provided ecosystem services for the future. Although seed storage behavior information is required to plan effective restoration programs, little is known about the rainforest species in Sri Lanka (Sacandé et al, 2004). Further, plant community-level studies on seed traits provide valuable information on the evolution of the seed traits and their environmental significance (Baskin & Baskin, 2014;Tweddle et al, 2003).…”

Effect of dormancy on the emergence of Tabernaemontana heterophylla seedlings in different substrates

“…Although there is a large amount of medicinal information about this genus, there is still a lack of knowledge about the possibilities of propagating this species, especially in terms of overcoming seed dormancy. Studies at the plant production level on the characteristics of seed dormancy are important to understand and determine the most appropriate propagation methods for a given species (Samarasinghe et al, 2022).…”

Seed (true seed plus endocarp) dormancy in Anacardiaceae in relation to infrafamilial taxonomy and endocarp anatomy

“…and Samarasinghe et al (2022) , de Melo et al (1979), Marín and Flores (2002,Salomão (2002),Braga et al (2014),Daibes et al (2019) andColado et al (2020) …”