BIOLOGIA DA GERMINAÇÃO E DESENVOLVIMENTO PÓS-SEMINAL DE DELONIX REGIA (Bojer ex Hook.) Raf. (Fabaceae: Caesalpinoideae)

Abstract

Delonix regia (Bojer ex Hook.) Raf., belongs to the family Fabaceae and subfamily Caesalpinoideae. It is a tree species native to Madagascar and widely adapted in the tropical and subtropical regions of the world. It presents ornamental, medicinal and industrial importance. Studies that elude the germination biology of native and exotic species can subsidize the seedlings production technology and management, for several purposes, mainly in the degraded natural areas recovery and commercial uses. The aim of this research was to study the D. regia seed germination biology, focusing on the effects promoted by different scarification treatments, morphoanatomy and reserve mobilization during post-seminal development and antioxidative responses in the germination. Seeds were collected from the soil bank and the experiments were carried out in a completely randomized design. D. regia seeds present physical dormancy and different germinative responses to thermal, mechanical and chemical scarification. Thermal scarring at 90°C for 1 and 3 minutes and mechanical scarification with sandpaper on the opposite side of the embryo were the most efficient in overcoming physical. Seeds exposed to sulfuric acid may have damaged internal membranes. The D. regia seedlings conclude their development at 11° DAS and are of the phenee-epigene-cotyledon type. Proteins and lipids constitute the initial reserves in the cotyledons and are mobilized during the seedling development. The starch reserves were completely depleted in the 30° DAS and coincided with the period in which the cotyledons had subsided. Concentrations of hydrogen peroxide and superoxide were observed throughout the seed germination and possibly acted on the signaling of gibberellic acid biosynthesis. The enzymes catalase, ascorbate peroxidase, peroxidase and superoxide dismutase act on the anti-oxidative responses, removing hydrogen peroxide and superoxide. The α- and β-amylase enzymes present activity during the D. regia seeds germination, in the mobilization of starch reserves mobilization. Together, the data allow us to observe that this species, after overcoming physical numbness and beginning of imbibition, presents a rapid metabolism that stimulates the hormones synthesis that stimulate the reserves mobilization and promote the formation of new compounds and energy.