Germinação in vitro e desenvolvimento pós-seminal de plântulas de Pilosocereus aurisetus (Werderm.) Byles & G.D. Rowley (Cactaceae)

Abstract

Pilosocereus aurisetus is a species of cactus of economic and environmental importance, but the predatory exploitation led the species to be listed as threatened with extinction. P. aurisetus propagation occurs mainly in natural environment by sexual reproduction, though there is no record of germination, viability and morphology of post-seminal seeds of this species. Thus, the objective of this study was to evaluate the germination and describe the morphology of post-seminal development of seeds of P. aurisetus. For this purpose, seeds stored at ambient conditions for 19 months were treated as follows: soaking in water for 24 hours, pre-cooling, soaking in solution of gibberellin in concentrations of 250 mg L-1 and 500 mg L-1 and a control. The seeds were germinated on MS medium for 30 days, when the germination percentage was evaluated. The statistical design was completely randomized with five treatments and four replications with 25 seeds per plot. The post-seminal characterization was performed for a period of 60 days using a stereomicroscope based on the International Rules for Testing Seeds. A higher percentage of germination was observed in the control or when soaked for 24 hours, with 90% and 83% respectively. The morphology of the post-seminal seeds indicated that the P. aurisetus germination is epigeous with reservation hypocotyl, seedlings changes lap region to emit roots and bristles present in shoot apex even in early stages of cotyledon expansion. The early differentiation and the formation of the ribs begin 60 days after germination with the development of the epicotyl.