Breaking physical dormancy in seeds of Pseudosamanea cubana (Fabaceae), an endemic and Critically Endangered tree in Cuba

Abstract

Pseudosamanea cubana is a Cuban endemic tree that is Critically Endangered. The species has a very restricted range, mainly in dry sites near the southern coast of eastern and western Cuba, but was recently discovered on the north coast of western Cuba (Punta Guanos, Matanzas). This species is used in Cuban forestry systems because of its high timber value, but nothing is known about the germination mechanisms of seeds from natural sites. Therefore, the main objective of this work was to identify the seminal dormancy class of fresh seeds of P. cubana collected in the northern area of Matanzas (Punta Guanos). For this purpose, morphophysiological characterization, imbibition test and application of pregermination treatments to seeds collected from the coastal xeromorphic scrub and microphyllous evergreen forest of the study site were carried out. Seeds showed low initial moisture content (10.2%), high percentage distribution of seed biomass to the canopy structures (55.3%), high tolerance to desiccation, presence of physical dormancy (PY), and rapid hydration and germination once PY was removed. The best pregermination treatment to increase germination was achieved with sulfuric acid scarification for one hour, which reached 97% final germination in one day. Practical recommendations are given to increase germination and seedling establishment in nursery conditions and direct seeding in the field.