Abstract

BILLARD, Cristina Ester; DALZOTTO, Carlos Alberto  and  LALLANA, Víctor Hugo. Germination of Bletilla striata (Thunb.) Rchb. f. in liquid medium and plant evolution in semi-solid medium. Investig. Agrar. [online]. 2013, vol.15, n.1, pp.7-14. ISSN 2305-0683.

The aims of this work were to evaluate a) in vitro germination of Bletilla striata seeds in liquid media and b) in vitro growing in semi-solid culture medium until rustication. B. striata seeds were disinfected with 0.5% sodium hypochlorite and rinsed 3 times with sterilized distilled water. Two treatments were applied: T1 (distilled water) and T2 (Murashige & Skoog (MS) liquid culture medium, half its concentration + 30 g L-1 of sacarose). Forty nine days after sowing (das), the growing stages and quantity of germinated and non-germinated seeds were evaluated. T2 explants were subcultivated to a semi-solid culture medium at half its concentration. They were classified in Group 1: protocorms; Group 2: protocorms with 1 to 2 slightly visible leaves and Group 3: seedlings with 2 to 3 small leaves and 1 root. They were cultured in growth chamber at 24 ± 1ºC and a photoperiod of 16 h. After 5 growing months, plants were established ex-vitro in trays with equal parts of pine bark substrate, vegetal carbon and sphagnum moss. Green embryos became visible 17 das. After 49 das, germination percentage was 23% and 100% in T1 and T2 respectively. After 156 days of in vitro culture, the best multiplication rate of vegetative shoots (66%), shoots with pseudobulbs (77%) and 23 mm of plant height was achieved in Group 3 seedlings. Ex-vitro plants survived without death or pathogen attack problems.

Keywords : Terrestrial orchids; germination; axenic culture; multiplication rate.

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