Micropropagation of Dyckia agudensis Irgang & Sobral : an extinction threatened bromeliad

Dyckia agudensis is an endemic species, that occurs on the Agudo hill, Agudo County (RS), it is considered threatened of extinction. The aim of this study was to develop a micropropagation protocol for this species to aid its conservation. The seeds were disinfected and germinated in vitro. Seedlings were submitted to the treatments of 0; 0.5; 1.0 or 2.0 mg.L-1 of BAP and IBA (same concentration) at 15 days of germination. The MS medium was supplemented with 2 ml.L-1 of Fuji vitamins, 30 g.L-1 of sucrose, and solidified with 6 g.L-1 of agar. After 60 days of cultivation, plantlets were transferred to a multiplication and regeneration medium. The medium was MS with 2 ml.L-1 of Fuji vitamins, 30 g.L-1 of sucrose, 0.5 mg.L-1 of BAP, and 7 g.L-1 of agar. The rooting medium was MS without growth regulators. The disinfection process obtained 85% of success. The same concentrations of BAP and IBA on the seedlings followed a quadratic regression, increasing shoot and bud numbers and swelling percentage, but reduced the percentage of rooting. The maximum efficacy was obtained close to 1.0 mg.L-1 of BAP and IBA in the culture medium. The m ultiplication phase proceeded together with the regeneration. The isolated shoots rooted without growth regulators. The acclimatization process was carried out in a hydroponic system for 15 days before transferring to the substrate.