IN VITRO CULTURE OF SPORES FROM WOODWARDIA FIMBRIATA SMITH

Woodwardia fimbriata Smith is a fern species belonging to the family Blechnaceae. It is native from western North America and known by the common name of giant chain fern. The present study reports Woodwardia fimbriata in vitro spore germination, gametophyte and sporophyte development and subsequent acclimatization of young plants to ex vitro conditions. Spores of W. fimbriata were obtained by exchange with other botanical gardens (via Index Seminum). Spores were successfully surface sterilized with commercial bleach and germination took place in liquid culture medium, consisting in half-strength Murashige and Skoog mineral salts and 2% sucrose. For sporophyte induction and development, gametophytes were transferred to different semi-solid (0.25% gelrite) culture media, consisting on half-strength Murashige and Skoog mineral salts and 2% sucrose, supplemented with five concentrations of NaH2PO4 (0, 50, 100, 150 and 200 mg/L) or to peat:perlite (1:1) sterile substrate. Two different photon flux density levels were also compared during the process. Best results concerning sporophyte number were observed on peat:perlite substrate (3.92 sporophytes/gametophytic cluster) and 75 µmol/m2/s. Well-developed sporophytes were potted in peat:perlite (1:1) compost and transferred to acclimatization conditions. Survival rates ranged from 90 to 95%.