EFFECT OF MEDIUM, KINETIN AND OSMOTIC AGENTS ON THE in vitro MORPHOGENETIC RESPONSE OF Astrophytum myriostigma (CACTACEA)

Abstract

Astrophytum myriostigma is a cactacea considered as threatened by extinction on the locations where it grows wild. As an alternative procedure for its conservation, the present work describes the effect of culture medium, kinetin, and osmotic agents on germination, shoot growth, formation and rooting in vitro. Seeds were sterilized with sodium hypochlorite-Tween 20 and ethanol and germinated on half strength concentration MS (½ MS) and Schenk-Hildebrandt (SH) media. Germination and plant growth (recorded as an increased in epicotyl and root length and gain in fresh and dry weight) were two to six fold higher on ½ MS than in SH. To induce shooting, longitudinal segments were grown into MS containing 0.5 mg L^-1 (C0.5), 1 mg L^-1 (C1) y 2 mg L^-1 (C2) of kinetin. The highest shoot number (14 shoots per explant) was obtained on C2 medium. To promote a higher number of compact shoots and rooting, shoots were transferred to ½ MS medium containing 1 or 2 % manitol or polyethylenglycol. After eight weeks well defined and compact plants were obtained under the four treatments.