Seed characterization and germination morpho-physiology of Simira gardneriana (Rubiaceae)

Abstract: Simira gardneriana (Rubiaceae) is a newly discovered tree species endemic to the Caatinga. For this reason, studies aimed at propagation, seed and seedlings analysis are essential for morphology, identification, classification, and conservation. Our objective was to characterize the seeds, the morpho-physiology of germination and seedling establishment of S. gardneriana. Therefore, we performed physical, biometric, biochemical, and morphological characterization of the seeds, as well as an evaluation of the germination process and seedling establishment. Hydration of seeds was carried out by three methods (immersion in water, on a wire mesh, and between paper rolls) and at two temperatures (25 and 30 °C). Morphological characterization of the seedlings was performed on paper substrate at 30 °C for 28 days. Seeds of S. gardneriana are orthodox, amylo-lipid, have an endosperm and do not exhibit physical dormancy. Hydration and germination of the seeds can be achieved in a paper roll at 30 °C with root protrusion on the sixth day, and complete seedling formation on the 28th day after sowing. Seedlings of S. gardneriana are phanero-epigeal cotyledonous with photosynthetic cotyledons and have ability to regrow the root system. Characterization of S. gardneriana seeds, germination and seedlings contributes to its propagation and may help in subsequent taxonomic and phylogenetic studies in Rubiaceae.